Natural and Historical Heritage of the Lisbon Botanical Gardens: An Integrative Approach with Tree Collections

Abstract

Botanical gardens have long contributed to plant science and have played a leading role in ex situ conservation, namely of threatened tree species. Focusing on the three botanical gardens of Lisbon (i.e., Botanical Garden of Ajuda—JBA, Lisbon Botanical Garden—JBL, and Tropical Botanical Garden—JBT), this study aims to reveal their natural heritage and to understand the historical motivations for their creation. Our results showed that these gardens contain a total of 2551 tree specimens, corresponding to 462 taxa, within 80 plant families. Of these, 85 taxa are found in the three gardens, and more than half of the taxa are hosted in JBL (334 taxa), whereas 230 and 201 taxa were recorded in JBT and JBA, respectively. The motivations for the creation of each garden are reflected in the different geographic origins of the trees they host in their living collections. The Palearctic species are dominant in JBA and JBL, and Tropical trees prevail in JBT. With more than 250 years of history, these gardens hold an invaluable natural and historical heritage, with their living collections providing valuable sources of information for the conservation of threatened plant species, at local and global scales.

1. Introduction

Biodiversity loss is a global phenomenon [1]. Adding to the conservation of species diversity in their natural habitats, the loss and degradation of urban environments made the preservation of urban ecosystems and the promotion of their biodiversity particularly important since the beginning of the 21st century [2]. Many cities still include remains of previous forests and trees that should be actively managed and preserved, namely in urban parks or woodlots [3]. Moreover, botanical and environmental awareness will be better raised among the community by providing education and places to learn about the plants and their conservation, and the botanical gardens play a relevant role in this context [4,5].

Botanical gardens are institutions that keep well-documented collections of living plants and seed banks, and are thus fundamental for conservation, education, and science [6,7]. Since the 1970s, the conservation of species outside their natural habitat (ex situ conservation), namely of threatened tree species, is encouraged by the International Union for Conservation of Nature (IUCN) and Botanic Gardens Conservation International (BGCI) [8]. As unique urban green spaces, the botanical gardens offer the potential to restore populations of threatened species, as their living collections and seed banks are insurance against the extinction of species in their natural habitats and provide means to reintroduce or reinforce their populations thereby making their survival possible [9,10].

In plant conservation, trees are widely recognized as critically important to the planet and population at the economic, cultural, and ecological levels [7]. However, their numbers have been declining in situ due to, e.g., climate change, overgrazing, agriculture, and logging [11]. According to the IUCN Red List, ca. 10,000 tree species are threatened with extinction worldwide [12]. Several studies have also recognized that trees are key elements in urban nature, as their presence provides numerous services to the urban ecosystem in ecological (i.e., climate, air quality, hydrology, soil, and biodiversity conservation), social, cultural, and aesthetic terms [13].

Lisbon, capital of Portugal, has unique characteristics owing to its location in Southwest Europe, in a transition zone between the Atlantic Ocean and the Mediterranean Sea, and between Africa and Eurasia, which allows it to host a higher average biodiversity than other European cities [14]. According to the municipality, Lisbon has about 148 gardens and parks, among which are three botanical gardens: Botanical Garden of Ajuda (hereafter, JBA), Lisbon Botanical Garden (hereafter, JBL), and Tropical Botanical Garden (hereafter, JBT) (see Figure 1), all of them belonging to the University of Lisbon. Lisbon is the only city in Portugal housing three botanical gardens, and they hold a rich natural and historical heritage, a valuable scientific resource to promote interdisciplinary research activities between the different schools of the University, as well as with worldwide institutions interested in the study of plant diversity and conservation. These three botanical gardens are very different, created at different times but with common overall purposes: research, plant conservation, horticulture, and education. Surely, the study of these gardens and of their collections would enhance the current understanding on Garden Art History and Plant Diversity, but the knowledge of this heritage is often incomplete and outdated.

Figure 1.

Location of the three Botanical Gardens in Lisbon. Right-top: Botanical Garden of Ajuda (JBA); right-center: Lisbon Botanical Garden (JBL); and right-bottom: Tropical Botanical Garden (JBT).

Knowing the botanical and historical heritage of the three Botanical Gardens of Lisbon, and what it represents, is essential to provide the first global measurement of ex situ conservation of living tree collections. Rivers et al. [10] advocate the need to divulge the ex situ collections housed in botanical gardens and arboreta, to plan future collecting efforts and to adopt integrated global approaches to protect threatened tree species.

With the present work, we aimed to contribute to disseminating the heritage represented by the Botanical Gardens of Lisbon, by coupling the history and the characteristics of the tree layer that dominates them. With this approach, we intended to explain why the presence of three Botanical Gardens in Lisbon is not redundant and to highlight their continued relevance for knowledge and for urban sustainability.

2. Results

2.1. History of the Botanical Gardens of Lisbon

2.1.1. Botanical Garden of Ajuda (JBA)

The first Portuguese botanical garden, Jardim Botânico da Ajuda (Botanical Garden of Ajuda, see Figure 1), was installed on the hill slope of Ajuda after the big 1755 earthquake. Founded in 1768, during the reign of José I (1714–1777) by the indication of his state secretary, Sebastião Carvalho e Mello (1699–1782), the garden was created by the Italian naturalist Domingos Vandelli (1735–1816), who was its first director. Along with the garden, the Royal Cabinet of Natural History, a Chemistry Laboratory, the Casa do Risco, where designers created scientific illustrations, and a Specialized Library were also created, as well as, after 1777, a cabinet of Experimental Physics.

The Royal Cabinet of Natural History became one of the richest European scientific institutions, as a result of the “Philosophical Journeys” to the Portuguese territories overseas, after the 1780s. For this reason, its collection caught great attention in Europe, particularly of naturalists from the Musée National d’Histoire Naturelle de Paris. An example of this was the visit of Étienne Geoffroy Saint-Hilaire (1772–1844), in 1807, who studied and selected specimens from JBA to enrich the collection of the Jardin des Plantes, in Paris. During the French invasions, part of the collections of the garden and of the Royal Cabinet was taken by the Napoleonic troops to the present Musée National d’Histoire Naturelle in Paris. Another part was taken to the Botanical Garden of Rio de Janeiro, when the Portuguese royal family left Lisbon and went to Brazil, in 1807, before the Napoleonic forces invaded Lisbon.

The second director of JBA was Félix da Silva e Avelar Brotero (1744–1828), a famous Portuguese naturalist that Vandelli met in Coimbra, a pioneer in the studies of Botany in Portugal; he wrote the first Portuguese Flora and started the first practical school of Botany of the country at JBA. In 1836, the administration of the garden was assigned to the Academy of Sciences of Lisbon, and its patrimony was once again split up. In January 1837, the Polytechnic School (later, Faculty of Sciences of the University of Lisbon) was created in the center of Lisbon, and its association with a botanical garden was considered indispensable. As a result, some collections of JBA were transferred there in October 1838. Since 1910, the direction of JBA is the responsibility of Instituto Superior de Agronomia, University of Lisbon. In 1944, JBA was listed as Imóvel de Interesse Público (“Building of Public Interest”) by the Ministry of Culture.

2.1.2. Lisbon Botanical Garden (JBL)

The Jardim Botânico de Lisboa (Lisbon Botanical Garden, see Figure 1) was created in 1873, with many collections brought from JBA. Inaugurated in 1878, it is presently part of the National Museum of Natural History and Science, which is responsible for the garden’s management. It was a scientific garden intended to complement teaching and botany research at the former Polytechnic School. The chosen place, Mount Olivete, had already more than two centuries of tradition in the study of botany, with the Jesuit College of Cotovia here established between 1609 and 1759. To install the garden, a draft directive was made in 1843. However, plantations only began in 1873, by the initiative of the Count of Ficalho (1837–1903) and Andrade Corvo (1824–1890), teachers at the Polytechnic School. The collection of the enormous diversity of living plants was first made by the German Edmund Goëze (1838–1929) and the French Jules Daveau (1852–1929), from all the territories under Portuguese rule at the time. Goëze, the first chief gardener, outlined the “Class” and Daveau was in charge of the “Arboretum”. Between 1892 and 1909, the French Henri Cayeux, the second chief-gardener, made important contributions to the embellishment of this garden, by introducing more species and creating new varieties of plants. That is the case of the introduction of succulent dahlias and the creation of the hybrid Dombeya × cayeuxii and of the rose cultivar “Belle Portugaise”.

The most significant intervention in the garden occurred in the late 1930s and early 1940s. Under director Ruy Telles Palhinha (1871–1957), the original systematic ordering of the upper terrace of JBL was replaced by ecologically meaningful groups of species. In 2010, JBL was listed as a “National Monument” by the Ministry of Culture.

2.1.3. Tropical Botanical Garden (JBT)

The Jardim Botânico Tropical (Tropical Botanical Garden, see Figure 1), initially “Colonial Garden”, was created by royal decree in 1906, under the rule of King Carlos I and by the initiative of Counsellor Manuel António Moreira Júnior, the Navy and Overseas Minister, and aimed to support the teaching of Tropical Agriculture.

The French landscape gardener Henri Navel (1878–1963), who studied at the National School of Horticulture of Versailles and worked as a gardener in some important gardens (e.g., Royal Botanic Gardens, Kew), had the task to prepare the space for its new function as a colonial garden, between 1910 and 1917. The director position was inherently held by the full professor of the “Economic Geography and Colonial Cultures” chair at the Instituto Superior de Agronomia (University of Lisbon).

The celebrations of the 800th anniversary of Portugal as an independent state and of the 300 years after the restoration of national independence, which took place in Belém with the 1940s “Exhibition of the Portuguese World”, left their mark on the morphology and identity of JBT, where the exhibitions concerning the Tropics were concentrated. The program of this section aimed to portray Portugal as the third colonial world power. Buildings, some still existing, and temporary pavilions were built, each dedicated to one of the colonies, and recreating African villages.

In 1944, the “Colonial Garden” was merged with the “Colonial Agriculture Museum”, also formally created in 1906, resulting in the Jardim e Museu Agrícola Colonial (Agriculture and Colonial Garden and Museum). Since its creation, the garden was dependent on the Instituto Superior de Agronomia. In 1951, the name changed to Jardim e Museu Agrícola do Ultramar (Overseas Garden and Museum of Agriculture), and in 1974 it became part of the Instituto de Investigação Científica Tropical (Tropical Research Institute). In 2006 it received its current name, and in 2007 it was listed as a National Monument by the Ministry of Culture. In August 2015, JBT became part of the University of Lisbon, under the administration of the National Museum of Natural History and Science.

2.2. Tree Collections

The tree layers of the three Botanical Gardens of Lisbon contain a total of 2551 specimens corresponding to 462 taxa (i.e., 448 species, nine subspecies, four varieties, and one form). Of the 462 taxa inventoried, 85 are shared by the three gardens, 130 by JBA and JBL, 146 by JBL and JBT, and 111 by JBA and JBT (Figure 2). More than half of the taxa recorded in our study were found in JBL (334 taxa), whilst in JBT and JBA 230 and 201 taxa were recorded, respectively (Table 1; Figure 2). The family, habit, taxonomic classification, and native distribution of each taxon are described in Table 1.

Figure 2.

Euler diagram showing the number of taxa of the three Botanical Gardens of Lisbon (JBA, JBL, JBT). The overlapping shapes represent taxa existing in two or three of the gardens.

Table 1.

Taxa found in the arboreal stratum of the three Botanical Gardens of Lisbon (JBA—Botanical Garden of Ajuda; JBL—Lisbon Botanical Garden; and JBT—Tropical Botanical Garden) in 2021: family, scientific name, occurrence, habit and native distribution.

Family/Taxa	JBA	JBL	JBT	Habit	IUCN a	Native Distribution
Anacardiaceae
Harpephyllum caffrum Bernh.		X		Tree	LC	Afrotropical—Afrotemperate
Pistacia lentiscus L.	X	X		Shrub or Tree	LC	Palearctic
Pistacia vera L.			X	Tree	NT	Palearctic
Pleiogynium timoriense (A.DC.) Leenh.		X		Tree	LC	Australotemperate—Oriental
Schinus latifolia (Gillies ex Lindl.) Engl.		X		Tree	NE	Neotropical
Schinus molle L.			X	Tree	NE	Andean—Neotropical
Schinus terebinthifolia Raddi	X	X	X	Tree	NE	Neotropical
Spondias mombin L.		X		Tree	LC	Andean—Neotropical
Annonaceae
Annona cherimola Mill.		X	X	Tree	LC	Andean
Apiaceae
Heteromorpha arborescens var. abyssinica (Hochst. ex A. Rich.) H. Wolff		X		Tree	NE	Afrotropical—Afrotemperate
Apocynaceae
Acokanthera oblongifolia (Hochst.) Benth. and Hook.f. ex B.D.Jacks.		X		Tree	LC	Afrotropical—Afrotemperate
Acokanthera oppositifolia (Lam.) Codd.			X	Tree	LC	Afrotropical—Afrotemperate
Carissa bispinosa (L.) Desf. ex Brenan		X		Shrub	LC	Afrotropical—Afrotemperate
Carissa macrocarpa (Eckl.) A.DC.	X	X		Shrub	LC	Afrotropical—Afrotemperate
Cascabela thevetia (L.) Lippold	X	X	X	Shrub	LC	Nearctic—Neotropical
Nerium oleander L.	X	X	X	Shrub	LC	Afrotropical—Oriental—Palearctic
Plumeria alba L.	X		X	Shrub	NE	Neotropical
Aquifoliaceae
Ilex aquifolium L.	X	X		Tree	LC	Palearctic
Ilex perado Aiton subsp. azorica Tutin		X		Tree	NE	Palearctic
Araliaceae
Oreopanax nymphaeifolius (Hibberd) Decne. and Planch. ex G.Nicholson		X	X	Shrub or Tree	NE	Neotropical
Plerandra elegantissima (H.J.Veitch ex Mast.) Lowry, G.M.Plunkett and Frodin	X	X		Tree	EN	Neoguinean
Pseudopanax lessonii (DC.) K.Koch		X		Tree	NE	Neozelandic
Schefflera actinophylla (Endl.) Harms		X		Tree	LC	Australotropical—Oriental
Schefflera venulosa (Wight and Arn.) Harms		X		Shrub or Tree	NE	Oriental
Tetrapanax papyrifer (Hook.) K.Koch		X		Shrub	LC	Oriental
Araucariaceae
Agathis robusta (C.Moore ex F.Muell.) F.M.Bailey	X	X	X	Tree	LC	Australotemperate—Neoguinean
Araucaria angustifolia (Bertol.) Kuntze		X		Tree	CR	Neotropical
Araucaria bidwillii Hook.	X	X	X	Tree	LC	Australotemperate
Araucaria columnaris (G.Forst.) Hook.		X	X	Tree	LC	Neoguinean
Araucaria cunninghamii Mudie	X	X	X	Tree	LC	Australotemperate—Neoguinean
Araucaria heterophylla (Salisb.) Franco	X	X	X	Tree	VU	Neozelandic
Arecaceae
Archontophoenix cunninghamiana (H.Wendl.) H.Wendl. and Drude		X		Rosette tree	NE	Australotemperate
Arenga pinnata (Wurmb) Merr.		X		Rosette tree	NE	Oriental
Bismarckia nobilis Hildebrandt and H.Wendl.			X	Rosette tree	LC	Afrotropical
Brahea armata S.Watson		X	X	Rosette tree	LC	Neotropical
Brahea edulis H.Wendl. ex S.Watson		X	X	Rosette tree	EN	Neotropical
Butia capitata (Mart.) Becc.		X	X	Rosette tree	NE	Neotropical
Butia eriospatha (Mart. ex Drude) Becc.		X		Rosette tree	VU	Neotropical
Chamaedorea pochutlensis Liebm.			X	Rosette tree	LC	Nearctic
Chamaedorea tepejilote Liebm.			X	Rosette tree	NE	Neotropical
Chamaerops humilis L.	X	X	X	Rosette tree	LC	Palearctic
Howea forsteriana (F.Muell.) Becc.	X	X	X	Rosette tree	VU	Australotemperate
Livistona australis (R.Br.) Mart.		X	X	Rosette tree	NE	Australotemperate
Livistona chinensis (Jacq.) R.Br. ex Mart.		X	X	Rosette tree	NE	Oriental
Phoenix canariensis H.Wildpret	X	X	X	Rosette tree	LC	Afrotropical
Phoenix dactylifera L.	X	X	X	Rosette tree	NE	Afrotropical—Palearctic
Phoenix loureiroi Kunth		X	X	Rosette tree	LC	Oriental
Phoenix reclinata Jacq.		X	X	Rosette tree	LC	Afrotropical
Phoenix rupicola T.Anderson		X		Rosette tree	NT	Oriental
Rhapis excelsa (Thunb.) Henry	X	X	X	Rosette tree	NE	Oriental
Rhopalostylis baueri (Hook.f.) H.Wendl. and Drude		X		Rosette tree	NE	Australotemperate
Rhopalostylis sapida (Sol. ex G.Forst.) H.Wendl. and Drude		X		Rosette tree	NE	Neozelandic
Sabal bermudana L.H. Bailey		X	X	Rosette tree	EN	Neotropical
Sabal minor (Jacq.) Pers.		X	X	Rosette tree	LC	Nearctic—Neotropical
Sabal palmetto (Walter) Lodd. ex Schult and Schult.f.		X	X	Rosette tree	NE	Nearctic—Neotropical
Serenoa repens (W.Bartram) Small		X		Rosette tree	NE	Nearctic
Syagrus romanzoffiana (Cham.) Glassman		X	X	Rosette tree	NE	Neotropical
Trachycarpus fortunei (Hook.) H.Wendl.	X	X	X	Rosette tree	NE	Oriental
Trachycarpus martianus (Wall. ex Mart.) H.Wendl.		X		Rosette tree	NE	Oriental
Trithrinax brasiliensis Mart.		X		Rosette tree	DD	Neotropical
Washingtonia filifera (Rafarin) H.Wendl. ex de Bary	X	X	X	Rosette tree	NT	Nearctic—Neotropical
Washingtonia robusta H.Wendl.	X	X	X	Rosette tree	NE	Neotropical
Asparagaceae
Beaucarnea recurvata (K.Koch and Fintelm.) Lem.	X	X	X	Rosette tree	CR	Neotropical
Beaucarnea stricta (K.Koch and Fintelm.) Lem.	X			Rosette tree	VU	Neotropical
Cordyline australis (G.Forst.) Endl.	X	X	X	Rosette tree	NE	Neozelandic
Cordyline indivisa (G. Forst.) Endl.	X			Rosette tree	LC	Neozelandic
Dasylirion wheeleri S.Watson ex Rothr.		X		Rosette tree	LC	Neotropical
Dracaena draco (L.) L.	X	X	X	Rosette tree	VU	Afrotropical
Nolina parviflora (Kunth) Hemsl.		X		Rosette tree	NE	Neotropical
Yucca aloifolia L.	X	X	X	Rosette tree	NE	Nearctic—Neotropical
Yucca carnerosana (Trel.) McKelvey		X		Rosette tree	LC	Neotropical
Yucca gigantea Lem.	X	X	X	Rosette tree	NE	Neotropical
Yucca gloriosa L.	X	X		Rosette tree	LC	Nearctic
Yucca treculeana Carrière			X	Rosette tree	NE	Nearctic—Neotropical
Asphodelaceae
Aloidendron barberae (Dyer) Klopper and Gideon F.Sm.	X		X	Rosette tree	NE	Afrotropical—Afrotemperate
Asteraceae
Montanoa bipinnatifida (Kunth) K.Koch	X	X	X	Shrub or Tree	NE	Neotropical
Podachaenium eminens (Lag.) Sch.Bip. ex Sch.Bip.		X		Shrub	LC	Neotropical
Berberidaceae
Berberis bealei Fortune	X		X	Shrub	NE	Oriental
Berberis japonica (Thunb.) Spreng.		X		Shrub	NE	Palearctic
Betulaceae
Alnus cordata (Loisel.) Duby		X		Tree	LC	Palearctic
Betula pubescens Ehrh.		X		Tree	LC	Palearctic
Corylus avellana L.	X	X		Tree	LC	Palearctic
Ostrya carpinifolia Scop.		X		Tree	LC	Palearctic
Bignoniaceae
Catalpa bignonioides Walter	X	X	X	Tree	DD	Nearctic
Jacaranda mimosifolia D.Don	X	X	X	Tree	VU	Neotropical
Markhamia lutea (Benth.) K. Schum.			X	Tree	LC	Afrotropical
Radermachera sinica (Hance) Hemsl.		X		Tree	LC	Oriental—Palearctic
Spathodea campanulata P.Beauv.			X	Tree	LC	Afrotropical
Boraginaceae
Ehretia acuminata R.Br.		X		Tree	LC	Australotemperate—Oriental—Neoguinean
Ehretia anacua (Terán and Berland.) I.M.Johnst.		X		Tree	LC	Neotropical
Cactaceae
Cereus hildmannianus K.Schum.		X		Stem-succulent shrub	LC	Neotropical
Cereus hildmannianus subsp. uruguayanus (F.Ritter ex R.Kiesling) N.P.Taylor		X	X	Stem-succulent shrub	NE	Neotropical
Opuntia leucotricha DC.	X	X		Stem-succulent shrub	LC	Neotropical
Opuntia monacantha Haw.			X	Stem-succulent shrub	LC	Neotropical
Rhodocactus grandifolius (Haw.) F.M.Knuth		X		Stem-succulent shrub	LC	Neotropical
Calycanthaceae
Chimonanthus praecox (L.) Link	X	X		Shrub or Tree	LC	Oriental
Cannabaceae
Celtis australis L. subsp. australis	X	X	X	Tree	LC	Palearctic
Celtis caucasica Willd.		X		Tree	LC	Palearctic
Celtis occidentalis L.		X		Tree	LC	Nearctic
Celtis reticulata Torr.		X		Tree	NE	Nearctic
Celtis sinensis Pers.	X	X		Tree	LC	Oriental
Casuarinaceae
Casuarina cunninghamiana Miq.	X	X	X	Tree	NE	Australotemperate—Australotropical
Elaeodendron papillosum Hochst.		X		Tree	NE	Afrotropical—Afrotemperate
Euonymus europaeus L.	X	X		Shrub	NE	Palearctic
Euonymus japonicus Thunb.		X	X	Shrub	VU	Palearctic
Maurocenia frangula Mill		X		Tree	NE	Afrotemperate
Cercidiphyllaceae
Cercidiphyllum magnificum (Nakai) Nakai		X		Tree	NE	Palearctic
Combretaceae
Terminalia australis Cambess.		X		Tree	LC	Neotropical
Cornaceae
Cornus capitata Wall.		X		Tree	LC	Oriental
Cornus walteri Wangerin		X		Tree	LC	Oriental
Corynocarpaceae
Corynocarpus laevigatus J.R.Forst. and G.Forst.	X	X	X	Tree	NE	Neozelandic
Cupressaceae
Chamaecyparis lawsoniana (A.Murray bis) Parl.	X	X	X	Tree	NT	Nearctic
Cupressus sempervirens L.	X	X	X	Tree	LC	Palearctic
Hesperocyparis glabra (Sudw.) Bartel			X	Tree	LC	Nearctic
Hesperocyparis lusitanica (Mill.) Bartel	X	X	X	Tree	LC	Neotropical
Hesperocyparis macnabiana (A.Murray bis) Bartel			X	Tree	VU	Nearctic
Hesperocyparis macrocarpa (Hartw.) Bartel	X	X	X	Tree	LC	Nearctic
Juniperus cedrus Webb and Berthel.			X	Tree	EN	Afrotropical
Juniperus chinensis L.	X	X		Tree	LC	Oriental—Palearctic
Juniperus phoenicea L.	X			Tree	LC	Palearctic
Juniperus sabina L.	X			Tree	LC	Palearctic
Juniperus virginiana L.		X		Tree	LC	Nearctic
Metasequoia glyptostroboides Hu and W.C.Cheng		X		Tree	EN	Oriental
Platycladus orientalis (L.) Franco	X	X	X	Tree	NT	Palearctic
Sequoia sempervirens (D.Don) Endl.		X	X	Tree	EN	Nearctic
Taxodium distichum (L.) Rich.		X		Tree	LC	Nearctic
Taxodium distichum var. mexicanum (Carrière) Gordon and Glend.		X		Tree	NE	Neotropical
Tetraclinis articulata (Vahl) Mast.	X			Tree	LC	Palearctic
Thuja occidentalis L.	X	X	X	Shrub or Tree	LC	Nearctic
Thuja plicata Donn ex D.Don	X	X		Tree	LC	Nearctic
Curtisiaceae
Curtisia dentata (Burm.f.) C.A.Sm		X		Shrub or Tree	LC	Afrotropical—Afrotemperate
Didiereaceae
Portulacaria afra Jacq.	X	X	X	Shrub	LC	Afrotropical—Afrotemperate
Ebenaceae
Diospyros kaki L.f.	X		X	Tree	NE	Oriental—Palearctic
Diospyros lotus L.		X		Tree	LC	Palearctic
Diospyros virginiana L.			X	Tree	NE	Nearctic
Elaeagnaceae
Elaeagnus angustifolia L.	X			Shrub	LC	Palearctic
Elaeagnus pungens Thunb.	X			Shrub	LC	Oriental
Ericaceae
Arbutus unedo L.	X	X		Shrub or Tree	LC	Palearctic
Eucommiaceae
Eucommia ulmoides Oliv.			X	Tree	VU	Oriental
Euphorbiaceae
Alchornea cordifolia (Schumach. and Thonn.) Müll.Arg.			X	Shrub or Tree	LC	Afrotropical
Aleurites moluccanus (L.) Willd.			X	Tree	LC	Oriental
Baloghia inophylla (G.Forst.) P.S.Green		X		Tree	NE	Australotemperate
Euphorbia ingens E.Mey. ex Boiss.	X		X	Shrub	LC	Afrotropical
Euphorbia pulcherrima Willd. ex Klotzsch.	X		X	Shrub	LC	Neotropical
Euphorbia tirucalli L.	X		X	Shrub	LC	Afrotropical—Afrotemperate—Oriental
Euphorbia triangularis Desf. ex A. Berger		X	X	Shrub	LC	Afrotropical—Afrotemperate
Mallotus japonicus (L.f.) Müll.Arg.	X	X		Tree	NE	Palearctic
Ricinus communis L.		X	X	Shrub	NE	Afrotropical
Fabaceae
Albizia julibrissin Durazz.	X			Tree	NE	Oriental—Palearctic
Bauhinia acuminata L.	X		X	Shrub or Tree	LC	Australotropical—Oriental
Bauhinia forficata Link		X	X	Shrub or Tree	LC	Neotropical
Bauhinia purpurea L.			X	Shrub or Tree	LC	Oriental
Bauhinia variegata L.	X		X	Shrub or Tree	LC	Oriental
Calliandra tweediei Benth.	X			Shrub or Tree	LC	Neotropical
Castanospermum australe A.Cunn. ex Mudie	X			Tree	NE	Australotemperate
Ceratonia siliqua L.	X	X		Tree	LC	Palearctic
Cercis siliquastrum L.	X	X	X	Tree	LC	Palearctic
Dermatophyllum secundiflorum (Ortega) Gandhi and Reveal		X		Shrub or Tree	NE	Neotropical
Erythrina americana Mill.	X		X	Tree	NE	Neotropical
Erythrina caffra Thunb.		X	X	Tree	LC	Afrotropical—Afrotemperate
Erythrina crista-galli L.	X	X		Tree	LC	Neotropical
Erythrina lysistemon Hutch.		X		Tree	LC	Afrotropical—Afrotemperate
Erythrina speciosa Andrews	X			Tree	NE	Neotropical
Gleditsia triacanthos L.	X	X	X	Tree	LC	Nearctic
Inga edulis Mart.			X	Tree	LC	Neotropical—Andean
Leucaena leucocephala (Lam.) de Wit		X	X	Tree	NE	Neotropical
Libidibia paraguariensis (D.Parodi) G.P.Lewis	X			Tree	VU	Neotropical
Mimosa aculeaticarpa Ortega		X		Shrub	LC	Neotropical
Parkinsonia aculeata L.	X	X		Tree	LC	Andean—Nearctic—Neotropical
Peltophorum dubium (Spreng.) Taub.			X	Tree	LC	Neotropical
Prosopis chilensis (Molina) Stuntz	X			Tree	LC	Andean—Neotropical
Prosopis glandulosa Torr.	X			Tree	LC	Nearctic—Neotropical
Prosopis juliflora (Sw.) DC.			X	Tree	NE	Neotropical
Prosopis laevigata (Humb. and Bonpl. ex Willd.) M.C.Johnst.			X	Tree	LC	Neotropical
Robinia neomexicana A.Gray var. neomexicana		X		Tree	NE	Nearctic—Neotropical
Robinia pseudoacacia L.	X	X	X	Tree	LC	Nearctic
Schotia afra (L.) Thunb.	X			Tree	LC	Afrotropical—Afrotemperate
Schotia brachypetala Sond.		X		Tree	LC	Afrotropical—Afrotemperate
Schotia latifolia Jacq.	X		X	Tree	LC	Afrotropical—Afrotemperate
Senna didymobotrya (Fresen.) H.S. Irwin and Barneby		X	X	Shrub or Tree	LC	Afrotropical
Sophora davidi (Franch.) Skeels		X		Shrub	NE	Oriental
Sophora microphylla Aiton	X			Shrub or Tree	NE	Neozelandic
Styphnolobium japonicum (L.) Schott	X	X	X	Tree	NE	Oriental
Tara spinosa (Molina) Britton and Rose	X	X		Tree	NE	Andean—Neotropical
Tipuana tipu (Benth.) Kuntze		X	X	Tree	LC	Neotropical
Vachellia farnesiana (L.) Wight and Arn.	X			Tree	LC	Neotropical
Vachellia karroo (Hayne) Banfi and Galasso		X	X	Tree	NE	Afrotropical—Afrotemperate
Fagaceae
Fagus sylvatica L.		X		Tree	LC	Palearctic
Quercus alnifolia Poech		X		Tree	LC	Palearctic
Quercus coccifera L.	X	X		Shrub	LC	Palearctic
Quercus faginea Lam. subsp. broteroi (Cout.) A.Camus	X			Tree	NE	Palearctic
Quercus faginea Lam. subsp. faginea	X	X		Tree	LC	Palearctic
Quercus ilex L.		X		Tree	LC	Palearctic
Quercus libani G.Olivier		X		Tree	LC	Palearctic
Quercus rotundifolia Lam.	X		X	Tree	LC	Palearctic
Quercus suber L.	X	X	X	Tree	LC	Palearctic
Ginkoaceae
Ginkgo biloba L.	X	X	X	Tree	EN	Oriental
Hamamelidaceae
Parrotia persica C.A.Mey.		X		Tree	NE	Palearctic
Hydrophyllaceae
Wigandia urens (Ruiz and Pav.) Kunth		X		Shrub	LC	Neotropical
Juglandaceae
Carya illinoinensis (Wangenh.) K.Koch		X	X	Tree	LC	Nearctic
Juglans nigra L.		X	X	Tree	LC	Nearctic
Juglans regia L.		X		Tree	LC	Palearctic
Pterocarya fraxinifolia (Poir.) Spach	X			Tree	VU	Palearctic
Lamiaceae
Vitex agnus-castus L.	X	X	X	Tree	DD	Palearctic
Lauraceae
Cinnamomum burmanni (Nees and T.Nees) Blume	X		X	Tree	NE	Oriental
Cinnamomum camphora (L.) J.Presl	X	X	X	Tree	NE	Palearctic
Cinnamomum tamala (Buch.-Ham.) T.Nees and Eberm.		X		Tree	LC	Oriental
Cinnamomum verum J.Presl	X			Tree	NE	Oriental
Laurus azorica (Seub.) Franco			X	Tree	LC	Palearctic
Laurus nobilis L.	X	X	X	Tree	LC	Palearctic
Ocotea foetens (Aiton) Baill.	X	X	X	Tree	LC	Afrotropical
Persea americana Mill.	X	X	X	Tree	LC	Neotropical
Persea barbujana (Cav.) Mabb. and Nieto Fel.	X	X	X	Tree	LC	Afrotropical
Persea indica (L.) Spreng.	X	X	X	Tree	LC	Afrotropical
Lythraceae
Lagerstroemia indica L.	X	X	X	Tree	LC	Oriental
Punica granatum L.	X	X	X	Shrub	LC	Palearctic
Magnoliaceae
Liriodendron tulipifera L.		X		Tree	LC	Nearctic
Magnolia champaca (L.) Baill. ex Pierre	X			Tree	LC	Oriental
Magnolia compressa Maxim.		X		Tree	DD	Oriental
Magnolia grandiflora L.	X	X		Tree	LC	Nearctic
Magnolia tripetala (L.) L.		X		Tree	LC	Nearctic
Magnolia× soulangeana Soul.-Bod.		X		Tree	NE	Hybrid
Malvaceae
Brachychiton acerifolius (A.Cunn. ex G.Don) F.Muell.	X	X	X	Tree	NE	Australotemperate
Brachychiton bidwillii Hook.			X	Tree	NE	Australotemperate
Brachychiton discolor F. Muell.	X		X	Tree	NE	Australotemperate
Brachychiton populneus (Schott and Endl.) R.Br.	X	X	X	Tree	NE	Australotemperate
Brachychiton rupestris (T.Mitch. ex Lindl.) K.Schum.			X	Tree	NE	Australotemperate
Ceiba crispiflora (Kunth) Ravenna		X		Tree	NE	Neotropical
Ceiba insignis (Kunth) P.E.Gibbs and Semir		X	X	Tree	NE	Andean
Ceiba pentandra (L.) Gaertn.			X	Tree	LC	Neotropical
Ceiba speciosa (A.St.-Hil., A.Juss. and Cambess.) Ravenna	X	X	X	Tree	NE	Neotropical
Dombeya burgessiae Gerrard ex Harv.		X	X	Shrub	LC	Afrotropical
Dombeya rotundifolia (Hochst.) Planch.		X		Shrub or Tree	LC	Afrotropical—Afrotemperate
Dombeya tiliacea (Endl.) Planch.			X	Tree	LC	Afrotropical—Afrotemperate
Dombeya × cayeuxii André	X	X	X	Tree	NE	Hybrid
Firmiana simplex (L.) W.Wight	X	X		Tree	LC	Oriental
Grewia occidentalis L.		X		Tree	LC	Afrotropical—Afrotemperate
Hibiscus mutabilis L.	X	X	X	Shrub	NE	Oriental
Hibiscus rosa-sinensis L.	X	X	X	Shrub	NE	Oriental
Hibiscus syriacus L.	X	X	X	Shrub or Tree	NE	Oriental
Lagunaria patersonia (Andrews) G.Don	X	X		Tree	NE	Australotemperate
Malvaviscus arboreus Dill. ex Cav.	X		X	Shrub	LC	Neotropical
Pachira aquatica Aubl.			X	Tree	LC	Neotropical
Phymosia umbellata (Cav.) Kearney	X		X	Shrub or Tree	LC	Neotropical
Tilia × moltkei Späth ex C.K.Schneid.	X			Tree	NE	Hybrid
Tilia dasystyla Steven		X		Tree	LC	Palearctic
Tilia platyphyllos Scop.		X		Tree	LC	Palearctic
Tilia tomentosa Moench			X	Tree	LC	Palearctic
Meliaceae
Cedrela odorata L.	X		X	Tree	VU	Neotropical
Melia azedarach L.	X	X	X	Tree	LC	Australotemperate—Australotropical—Neioguinean—Oriental
Trichilia emetica Vahl			X	Tree	LC	Afrotropical
Trichilia havanensis Jacq.		X		Tree	LC	Neotropical
Menispermaceae
Cocculus laurifolius DC.		X		Shrub or Tree	NE	Oriental
Monimaceae
Peumus boldus Molina		X		Tree	LC	Andean
Moraceae
Broussonetia papyrifera (L.) L’Hér. ex Vent.	X		X	Tree	LC	Oriental—Palearctic
Ficus altissima Blume			X	Tree	LC	Oriental
Ficus aurea Nutt.		X		Tree	NE	Neotropical
Ficus benjamina L.	X	X	X	Tree	LC	Australotemperate—Oriental
Ficus carica L.	X	X	X	Tree	LC	Palearctic
Ficus coronata Spin		X		Tree	NE	Australotemperate
Ficus elastica Roxb. ex Hornem.	X		X	Tree	NE	Oriental
Ficus eximia Schott	X			Tree	LC	Neotropical
Ficus habrophylla G.Benn. ex Seem.		X		Tree	NE	Australotemperate
Ficus luschnathiana (Miq.) Miq.		X		Tree	LC	Neotropical
Ficus lyrata Warb.			X	Tree	NE	Afrotropical
Ficus macrophylla Desf. ex Pers.	X	X	X	Tree	NE	Australotemperate
Ficus microcarpa L.f.	X		X	Tree	LC	Australotemperate—Neoguinean—Oriental
Ficus religiosa L.	X	X	X	Tree	NE	Oriental
Ficus rubiginosa Desf. ex Vent.		X		Tree	NE	Australotemperate
Ficus rumphii Blume			X	Tree	NE	Oriental
Ficus superba (Miq.) Miq.		X		Tree	NE	Oriental
Ficus sur Forssk.		X		Tree	LC	Afrotropical
Ficus sycomorus L.		X	X	Tree	LC	Afrotropical
Ficus virens Aiton			X	Tree	LC	Australotemperate—Australotropical—Oriental
Maclura pomifera (Raf.) C.K.Schneid.		X	X	Tree	LC	Nearctic
Morus alba L.	X	X	X	Tree	NE	Oriental
Morus nigra L.	X			Tree	NE	Palearctic
Myricaceae
Myrica faya Dryand.	X	X		Shrub or Tree	LC	Palearctic
Myrtaceae
Agonis flexuosa (Willd.) Sweet		X		Tree	NE	Australotropical
Corymbia maculata (Hook.) K.D.Hill and L.A.S.Johnson			X	Tree	NE	Australotemperate
Eucalyptus camaldulensis Dehnh.	X	X	X	Tree	NT	Australotropical—Australotemperate
Eucalyptus cladocalyx F.Muell.		X		Tree	VU	Australotemperate
Eucalyptus cornuta Labill.		X		Tree	NT	Australotemperate
Eucalyptus diversicolor F.Muell.	X			Tree	LC	Australotemperate
Eucalyptus globulus Labill.			X	Tree	LC	Australotemperate
Eucalyptus gomphocephala A.Cunn ex DC.		X	X	Tree	VU	Australotemperate
Eucalyptus ovata Labill.			X	Tree	VU	Australotemperate
Eucalyptus robusta Sm.			X	Tree	NT	Australotemperate
Eucalyptus tereticornis Sm.		X	X	Tree	LC	Australotemperate
Eucalyptus × kirtoniana F.Muell.			X	Tree	NE	Australotemperate
Eugenia involucrata DC.	X			Shrub	LC	Neotropical
Eugenia myrcianthes Nied.			X	Tree	LC	Neotropical
Eugenia uniflora L.	X	X		Tree	NE	Neotropical
Feijoa sellowiana (O.Berg) O.Berg		X	X	Shrub or Tree	LC	Neotropical
Leptospermum laevigatum (Gaertn.) F.Muell.		X		Tree	NE	Australotemperate
Lophostemon confertus (R.Br.) Peter G.Wilson and J.T. Waterh.		X	X	Tree	NE	Australotemperate
Melaleuca armillaris (Sol. ex Gaertn.) Sm.	X		X	Tree	NE	Australotemperate
Melaleuca citrina (Curtis) Dum.Cours.	X			Shrub	NE	Australotemperate
Melaleuca lanceolata Otto			X	Tree	LC	Australotemperate
Melaleuca leucadendra (L.) L.			X	Tree	NE	Australotropical—Neoguinean
Melaleuca linearis Schrad. and J.C.Wendl. var. linearis	X	X		Shrub	NE	Australotemperate
Melaleuca preissiana Schauer		X		Tree	LC	Australotemperate
Melaleuca rugulosa (Link) Craven	X			Shrub	NE	Australotemperate
Melaleuca styphelioides Sm.	X			Tree	NE	Australotemperate
Melaleuca viminalis (Sol. ex Gaertn.) Byrnes	X			Shrub	NE	Australotemperate
Melaleuca virens Craven	X			Shrub	NE	Australotemperate
Metrosideros excelsa Sol. ex Gaertn.		X	X	Tree	NE	Neozelandic
Myrtus communis L.	X	X	X	Shrub	LC	Afrotropical—Palearctic
Psidium cattleyanum Sabine	X	X	X	Shrub or Tree	NE	Neotropical
Psidium guajava L.	X		X	Tree	LC	Andean—Neotropical
Psidium guineense Sw.			X	Tree	LC	Andean—Neotropical
Syzygium cumini (L.) Skeels			X	Tree	LC	Oriental—Australotropical
Syzygium jambos (L.) Alston			X	Tree	LC	Oriental
Syzygium paniculatum Gaertn.	X	X		Tree	NE	Australotemperate
Ochnaceae
Ochna serrulata (Hochst.) Walp.		X	X	Shrub	LC	Afrotropical—Afrotemperate
Oleaceae
Fraxinus angustifolia Vahl subsp. angustifolia	X	X	X	Tree	LC	Palearctic
Fraxinus anomala Torr. ex S. Watson		X		Tree	LC	Nearctic
Fraxinus floribunda Wall.		X		Tree	LC	Oriental
Fraxinus ornus L.		X		Tree	LC	Palearctic
Fraxinus pennsylvanica Marshall	X	X		Tree	CR	Nearctic
Ligustrum japonicum Thunb.		X	X	Tree	NE	Oriental
Ligustrum lucidum W.T. Aiton	X	X	X	Tree	LC	Oriental
Ligustrum sinense Lour.		X	X	Tree	LC	Oriental
Olea capensis L.		X		Tree	NE	Afrotropical
Olea europaea L. subsp. europaea	X	X	X	Tree	DD	Palearctic
Olea europaea subsp. cuspidata (Wall. and G.Don) Cif.			X	Tree	NE	Afrotropical—Palearctic
Osmanthus fragrans Lour.			X	Shrub or Tree	LC	Oriental
Phillyrea latifolia L.	X	X	X	Tree	LC	Palearctic
Picconia azorica (Tutin) Knobl.	X	X		Tree	LC	Palearctic
Picconia excelsa (Aiton) DC.		X		Tree	VU	Afrotropical
Syringa vulgaris L.	X	X	X	Shrub	LC	Palearctic
Paulowniaceae
Paulownia tomentosa (Thunb.) Steud.	X	X	X	Tree	NE	Palearctic
Phyllanthaceae
Phyllanthus juglandifolius Willd.			X	Shrub or Tree	NE	Andean—Neotropical
Phytolaccaceae
Phytolacca dioica L.	X	X	X	Tree	NE	Andean—Neotropical
Pinaceae
Abies concolor (Gordon and Glend.) Lindl. ex Hildebr.		X		Tree	LC	Nearctic
Abies pinsapo Boiss.		X		Tree	EN	Palearctic
Cedrus atlantica (Endl.) Manetti ex Carrière		X	X	Tree	EN	Palearctic
Cedrus deodara (Roxb. ex D.Don) G.Don		X	X	Tree	LC	Oriental
Picea laxa (Münchh.) Sarg.		X		Tree	LC	Nearctic
Picea pungens Engelm.		X		Tree	LC	Nearctic
Pinus bungeana Zucc. ex Endl.		X		Tree	LC	Oriental
Pinus canariensis C.Sm.		X		Tree	LC	Afrotropical
Pinus halepensis Mill.		X		Tree	LC	Palearctic
Pinus nigra J.F.Arnold			X	Tree	LC	Palearctic
Pinus pinea L.	X	X	X	Tree	LC	Palearctic
Pinus sylvestris L.		X		Tree	LC	Palearctic
Pinus teocote Schiede ex Schltdl. and Cham.			X	Tree	LC	Palearctic
Pinus torreyana Parry ex Carrière		X		Tree	CR	Nearctic
Piperaceae
Piper jacquemontianum Kunth			X	Shrub	NE	Neotropical
Pittosporaceae
Pittosporum crassifolium Banks and Sol. ex A.Cunn.		X		Shrub or Tree	NE	Neozelandic
Pittosporum tobira (Thunb.) W.T.Aiton	X	X	X	Shrub or Tree	NE	Oriental—Palearctic
Pittosporum undulatum Vent.	X	X	X	Tree	NE	Australotemperate
Pittosporum viridiflorum Sims		X		Shrub or Tree	NE	Afrotropical
Platanaceae
Platanus × hispanica Mill. ex Münchh.	X	X	X	Tree	NE	Hybrid
Podocarpaceae
Afrocarpus mannii (Hook.f.) C.N.Page	X	X	X	Tree	VU	Afrotropical
Podocarpus macrophyllus (Thunb.) Sweet	X			Tree	LC	Oriental
Podocarpus neriifolius D.Don		X	X	Tree	LC	Oriental
Podocarpus totara G.Benn. ex D.Don		X		Tree	LC	Neozelandic
Primulaceae
Myrsine africana L.		X		Shrub	NE	Afrotropical—Afrotemperate—Oriental
Proteaceae
Banksia integrifolia L.f.	X	X		Tree	LC	Australotemperate
Grevillea olivacea A.S.George	X			Shrub	LC	Australotropical
Grevillea robusta A.Cunn. ex R.Br.	X	X	X	Tree	LC	Australotemperate
Grevillea thelemanniana Hügel ex Lindl.	X			Shrub	NE	Australotropical
Hakea laurina R.Br.	X			Shrub or Tree	VU	Australotemperate
Macadamia integrifolia Maiden and Betche		X	X	Tree	NE	Australotemperate
Macadamia ternifolia F. Muell.		X		Tree	EN	Australotemperate
Quillajaceae
Quillaja lancifolia D.Don		X		Tree	NE	Neotropical
Rhamnaceae
Colletia paradoxa (Spreng.) Escal.		X		Shrub	NE	Neotropical
Colletia spinosissima J.F.Gmel.		X		Shrub	LC	Andean—Neotropical
Fontanesia fortunei Carrière		X		Shrub or Tree	NE	Oriental
Frangula azorica Grubov			X	Tree	LC	Palearctic
Hovenia dulcis Thunb.		X		Tree	LC	Oriental
Noltea africana (L.) Rchb. f.	X			Shrub or Tree	LC	Afrotemperate
Paliurus spina-christi Mill.		X		Shrub	NE	Palearctic
Pomaderris apetala Labill.		X		Shrub or Tree	NE	Neozelandic
Rhamnus alaternus L.	X	X		Shrub	LC	Palearctic
Rhamnus cathartica L.	X	X		Tree	LC	Palearctic
Ziziphus jujuba Mill.	X	X	X	Tree	LC	Palearctic
Rosaceae
Cotoneaster coriaceus Franch.	X	X	X	Shrub	LC	Palearctic
Crataegus azarolus L.		X		Shrub or Tree	LC	Palearctic
Crataegus monogyna Jacq.	X	X		Shrub or Tree	NE	Palearctic
Eriobotrya japonica (Thunb.) Lindl.	X		X	Tree	NE	Oriental
Malus domestica (Suckow) Borkh.			X	Shrub or Tree	EN	Palearctic
Phoenix sylvestris (L.) Roxb.		X	X	Tree	NE	Oriental
Photinia serratifolia (Desf.) Kalkman		X	X	Shrub or Tree	NE	Oriental
Prunus avium (L.) L.			X	Tree	LC	Palearctic
Prunus azorica (hort. ex Mouill) Rivas Mart., Lousã, Fern. Prieto, J.C. Costa and C. Aguiar	X			Tree	NE	Palearctic
Prunus caroliniana (Mill.) Aiton		X		Tree	LC	Nearctic
Prunus cerasifera Ehrh. subsp. cerasifera	X	X	X	Tree	DD	Palearctic
Prunus laurocerasus L.		X	X	Tree	LC	Palearctic
Prunus lusitanica L.		X	X	Tree	EN	Palearctic
Prunus persica (L.) Batsch	X	X		Shrub or Tree	NE	Palearctic
Prunus × blireana André	X		X	Tree	NE	Hybrid
Pyracantha angustifolia (Franch.) C.K.Schneid.		X		Shrub	LC	Palearctic
Pyracantha crenulata (D.Don) M.Roem.			X	Shrub	NE	Oriental
Pyrus pyrifolia (Burm. f.) Nakai			X	Tree	NE	Oriental
Rhaphiolepis indica (L.) Lindl.	X	X	X	Shrub	NE	Oriental
Spiraea cantoniensis Lour.	X	X	X	Shrub	LC	Oriental
Stranvaesia nussia (Buch.-Ham. ex D.Don)		X		Tree	NE	Oriental—Palearctic
Rubiaceae
Coffea arabica L.	X		X	Shrub or Tree	EN	Afrotropical
Coffea racemosa Lour.			X	Shrub or Tree	NT	Afrotropical
Coprosma repens A.Rich.	X	X		Shrub	NE	Neozelandic
Gardenia thunbergia Thunb.		X	X	Shrub or Tree	NE	Afrotropical—Afrotemperate
Rogiera amoena Planch.		X		Shrub or Tree	NE	Neotropical
Rogiera backhousii (Hook.f.) Borhidi		X		Shrub or Tree	NE	Neotropical
Rutaceae
Calodendrum capense (L.f.) Thunb.		X		Tree	LC	Afrotropical—Afrotemperate
Casimiroa edulis La Llave			X	Tree	LC	Neotropical
Citrus × aurantium L.	X	X		Tree	NE	Hybrid
Citrus glauca (Lindl.) Burkill		X		Shrub or Tree	NE	Australotemperate
Citrus trifoliata L.	X	X		Shrub or Tree	NE	Oriental
Citrus × limon (L.) Osbeck	X	X		Shrub or Tree	NE	Hybrid
Pilocarpus pennatifolius Lem.		X	X	Shrub or Tree	NE	Neotropical
Zanthoxylum armatum DC.		X	X	Shrub	LC	Oriental
Salicaceae
Dovyalis caffra (Hook.f. and Harv.) Warb.	X	X	X	Tree	LC	Afrotropical—Afrotemperate
Populus alba L.		X	X	Tree	LC	Palearctic
Populus nigra L.		X	X	Tree	DD	Palearctic
Salix × pendulina f. salamonii (Carrière) I.V.Belyaeva		X		Shrub or Tree	NE	Hybrid
Salix atrocinerea Brot.		X		Shrub or Tree	LC	Palearctic
Sapindaceae
Acer campestre L.	X			Tree	LC	Palearctic
Acer granatense Boiss.	X			Tree	LC	Palearctic
Acer monspessulanum L.	X	X		Tree	LC	Palearctic
Acer negundo L.		X		Tree	LC	Nearctic
Acer palmatum Thunb.		X		Tree	LC	Palearctic
Acer pseudoplatanus L.	X	X		Tree	LC	Palearctic
Aesculus glabra Willd.	X			Tree	LC	Nearctic
Aesculus hippocastanum L.		X	X	Tree	VU	Palearctic
Aesculus × carnea Zeyh.	X	X	X	Tree	NE	Hybrid
Dodonaea viscosa Jacq.	X		X	Shrub or Tree	LC	Afrotropical—Australotemperate—Australotropical—Neoguinean—Neotropical—Neozelandic—Oriental
Harpullia pendula Planch. ex F.Muell.		X		Tree	NE	Australotemperate
Hippobromus pauciflorus (L.f.) Radlk.		X		Tree	LC	Afrotropical—Afrotemperate
Koelreuteria bipinnata Franch.		X	X	Shrub or Tree	NE	Oriental
Koelreuteria paniculata Laxm.	X	X		Tree	LC	Oriental—Palearctic
Sapindus drummondii Hook. and Arn.		X	X	Tree	NE	Nearctic
Sapindus mukorossi Gaertn.		X	X	Tree	NE	Oriental—Palearctic
Sapindus saponaria L.		X		Tree	LC	Oriental
Sapotaceae
Chrysophyllum imperiale (Linden ex K.Koch and Fintelm.) Benth. and Hook.f.		X	X	Tree	EN	Neotropical
Sideroxylon inerme L.		X		Tree	NE	Afrotropical—Afrotemperate
Sideroxylon mirmulano R.Br.		X		Tree	EN	Afrotropical
Scrophulariaceae
Myoporum laetum G.Forst.	X	X		Tree	NE	Neozelandic
Simaroubaceae
Ailanthus altissima (Mill.) Swingle		X	X	Tree	NE	Palearctic
Solanaceae
Brugmansia aurea Lagerh.		X		Shrub	EW	Neotropical
Cestrum × cultum Francey		X		Shrub	NE	Hybrid
Nicotiana glauca Graham	X			Shrub	NE	Andean—Neotropical
Solanum crinitum Lam.		X		Shrub or Tree	NE	Neotropical
Stilbaceae
Halleria lucida L.		X		Shrub or Tree	LC	Afrotropical—Afrotemperate
Tamaricaceae
Tamarix africana Poir.	X	X		Shrub or Tree	LC	Palearctic
Tamarix gallica L.	X			Shrub or Tree	LC	Palearctic
Tamarix parviflora DC.		X		Shrub or Tree	LC	Palearctic
Taxaceae
Cephalotaxus harringtonia (Knight ex J.Forbes) K.Koch		X	X	Shrub or Tree	LC	Oriental
Taxus baccata L.	X	X	X	Tree	LC	Palearctic
Torreya californica Torr.		X		Tree	VU	Nearctic
Theaceae
Camellia japonica L.	X	X		Shrub	LC	Palearctic
Ulmaceae
Ulmus minor Mill.	X			Tree	DD	Palearctic
Zelkova serrata (Thunb.) Makino	X	X		Tree	NT	Oriental—Palearctic
Urticaceae
Myriocarpa longipes Liebm.		X		Shrub or Tree	NE	Neotropical
Verbenaceae
Citharexylum spinosum L.		X		Shrub or Tree	LC	Neotropical
Duranta erecta L.	X	X	X	Shrub or Tree	LC	Nearctic—Neotropical
Viburnaceae
Sambucus nigra L.	X	X		Shrub or Tree	LC	Palearctic
Viburnum odoratissimum Ker Gawl.		X		Shrub	LC	Oriental
Viburnum rhytidophyllum Hemsl.		X		Shrub	NE	Oriental
Viburnum tinus L.	X	X	X	Shrub	LC	Palearctic
Xanthorrhoeaceae
Kumara plicatilis (L.) G.D.Rowley	X			Rosette tree	NE	Afrotemperate

^a EW, Extinct in Wild; CR, Critically Endangered; EN, Endangered; VU, Vulnerable; NT, Near Threatened; LC, Least Concern; DD, Data Deficient; NE, Not Evaluated [12].

There is no clear relationship between the area (ha) (i.e., green spaces) and the number of species in each botanical garden, as shown in Figure 3. Nevertheless, when comparing JBA with JBL, the number of species tended to increase with the garden area, as there are more varied habitat types in JBL able to accommodate a more diverse range of species. Moreover, species diversity can also reflect the path of each botanical garden over time and socioeconomic issues, taking into account the human and financial resources allocated to garden management. However, the greatest difference was caused by the 1941 hurricane, the strongest one affecting Portugal to date: the trees of the JBA, many of them close to 200 years old, were uprooted from the base, while the trees of the JBL were not affected.

Figure 3.

Relationship between garden green area and species richness, in each Botanical Garden of Lisbon (JBA, JBL, JBT); the area of each pie chart represents the number of specimens inventoried for the dominant taxonomic groups that occur in each garden.

The Eudicotyledons are the more numerous species in the three botanical gardens (76% in JBA; 73% in JBL; 73% in JBT), followed by the Gymnosperms (including Ginkgophyta and Coniferophyta) (10% in JBA; 12% in JBL; 10% in JBT), the Monocotyledons (9% in JBA; 11% in JBL; 13% in JBT), and finally the Magnoliids (6% in JBA; 4% in JBL; 4% in JBT) (Table 1; Figure 3).

A total of 80 plant families are represented, the Fabaceae being the dominant one (39 taxa), followed by the Myrtaceae (36 taxa). In contrast, 33 families (e.g., Casuarinaceae, Ginkgoaceae and Lamiaceae) are represented by one taxon only (Table 1). The most dominant families in JBT and JBL are the Arecaceae (ca. 10% and 8%, respectively) and the Fabaceae (ca. 9% and 6%, respectively), whereas the Fabaceae (11%) and the Myrtaceae (7%) are the main ones in JBA.

The most abundant species is Washingtonia robusta, with 106 specimens. In contrast, 171 taxa are represented by only one specimen (e.g., Abies pinsapo, Brugmansia aurea, Hesperocyparis macnabiana, Pinus torreyana) (see Table 1).

Among the three gardens, most of the inventoried taxa are trees sensu stricto (JBA, 60%; JBL, 62%; JBT, 64%), followed by shrubs (17% of the taxa in JBA, 12% in JBL, 11% in JBT); some taxa grow either as trees or shrubs (13% in JBA, 14% in JBL, 11% in JBT). Rosette trees correspond to 9% in JBA, 11% in JBL, and 13% in JBT; stem-succulent shrubs only represent 1% of the taxa in the three gardens (Table 1).

Among the taxa with an IUCN classification (64.1% of the recorded taxa; the other 166 taxa have no IUCN evaluation) (Table 1), 0.9% are categorized as CR (Araucaria angustifolia, Beaucarnea recurvata, Fraxinus pensylvanica, and Pinus torreyana), 3.2% as EN (e.g., Ginkgo biloba, Sequoia sempervirens, Sideroxylon mirmulans), 4.3% as VU (e.g., Dracaena draco, Howea forsteriana, Jacaranda mimosifolia), 2.2% as NT (e.g., Pistacia vera, Washingtonia filifera, Zelkova serrata), 51.5% as LC, 1.7% as DD, and 0.2% as EW (Brugmansia aurea, which was eradicated in the wild by indigenous populations due to its toxicity).

In JBA, about 1.0% of the taxa are classified as CR, 1.5% as EN, 4.0% as VU, 2.5% as NT, 51.7% as LC, and 2.5% as DD (Figure 4). In JBT, 0.4% of the taxa are classified as CR, 4.3% as EN, 5.2% as VU, 3.0% as NT, 49.1% as LC, and 2.2% as DD. JBL hosts 1.2% of taxa classified as CR, 3.6% as EN, 3.6% as VU, 2.1% as NT, 50.9% as LC, 2.1% as DD, and 0.3% as EW. A considerable portion of the species (JBA 36.0%, JBT 35.7% and JBL 36.2%) remains unevaluated by IUCN.

Figure 4.

IUCN classification of the taxa composing the arboreal stratum of the three Botanical Gardens of Lisbon. [EW, Extinct in Wild; CR, Critically Endangered; EN, Endangered; VU, Vulnerable; NT, Near Threatened; LC, Least Concern; DD, Data Deficient; NE, Not Evaluated]. The number of species belonging to each IUCN category is shown.

Comparing the three Botanical Gardens, 29 tree species stand out in JBL because of their conservation status worldwide, followed by JBT and JBA with 23 and 16 species, respectively (Table 1). Eleven of these taxa only occur in the JBL collection, namely Brugmansia aurea, while the other six species are exclusive to JBA and JBT collections.

Regarding the worldwide native distribution, 11 main groups were identified (Table 1), namely: Palearctic (20%) (e.g., Arbutus unedo, Ceratonia siliqua); Neotropical (18%) (e.g., Persea americana, Schinus terebinthifolia); Oriental (16%) (e.g., Ginkgo biloba, Ficus religiosa); Afrotropical (11%) (e.g., Persea barbujana, Phoenix canariensis); and Australotemperate (11%) (e.g., Araucaria bidwillii, Brachychiton populneus). Using the data presented in Table 1, a heatmap was constructed with the vertical columns representing the three botanical gardens and the horizontal lines the biogeographic regions (Figure 5); the resulting combination boxes were blue-colored according to a gradient from the highest number of taxa (darkest blue) to the lowest (white).

Figure 5.

Heatmap showing the biogeographic distribution of taxa found in each Botanical Garden of Lisbon (JBA, JBL, and JBT). Color intensity indicates the relative proportion of the taxa from the six most represented biogeographic origins.

The prevailing origin is the Palearctic, in JBA (27%) and JBL (22%), followed by the Neotropical, which corresponds to 16% and 17% of the taxa in both gardens, respectively. In JBT, the main origins are Neotropical (19%) and Oriental (18%), with a considerable number of useful plants such as Aleurites moluccanus, Cinnamomum burmanni, Casimiroa edulis, Feijoa sellowiana, Eugenia myrcianthes, Persea americana, Psidium cattleyanum or Syzygium jambos. The Afrotemperate, Andean, Australotropical, Neoguinean, and Neozelandic are the least represented regions in the three Gardens (less than 6% of taxa).

2.2.1. Remarkable Species of JBA

At JBA, worth noting are two splendorous Ficus macrophylla, and the emblematic dragon tree (Dracaena draco) (Figure 6A), probably one of the oldest specimens in the garden (over three centuries old). Other emblematic trees include the only living specimen of Schotia afra (Figure 6B) in a European botanical garden [15], Araucaria bidwillii, Zelkova serrata, Ocotea foetens, Quercus faginea and Phytolacca dioica. On the lower terrace, the boxwood hedges enclose some tree specimens which deserve special attention because of their size or shape, namely Lagerstroemia indica, Lagunaria patersonia, Dracaena draco, Araucaria heterophylla (Figure 6C), and Araucaria cunninghamii. It should be mentioned that Araucaria species are majestic trees, full of symbolism in Portuguese gardens.

Figure 6.

The iconic specimens of JBA: (A) Dracaena draco, probably one of the oldest specimens in the garden; (B) Schotia afra, the only living specimen in a European botanical garden; (C) Garden perspective showing the specimen of Araucaria heterophylla in the background (Photos: Cunha).

2.2.2. Remarkable Species of JBL

The collection of plants here is the most diverse among the three gardens. For instance, the outstanding diversity of palms (Figure 7A), brought from all continents, provides unexpected tropical scenarios at several points in the garden [16,17]. This garden holds some collections particularly worth mentioning and some species that stand out because of their conservation status worldwide, namely: Pinus torreyana, Metasequoia glyptostroboides, Chrysophyllum imperial (Figure 7B), Brahea edulis, Afrocarpus mannii, Taxodium distichum var. mexicanum or Dracaena draco (Figure 7C), among other species with conservation interest.

Figure 7.

The iconic specimens of JBL: (A) Garden perspective showing the outstanding diversity of palms; (B) Chrysophyllum imperiale; and (C) Dracaena draco (Photos A and C: Sachetti; Photo B: Forte).

2.2.3. Remarkable Species of JBT

Among the most notable specimens in JBT is the collection of rare palm trees, the exuberant Ficus macrophylla (one of the largest specimens in Europe) (Figure 8A), and a two-century-old Yucca gigantea (Figure 8B). Palms are a dominant element in the garden, as immediately perceived upon entrance, in the main avenue flanked by Washingtonia robusta and Washingtonia filifera, inspired by the Botanical Garden of Rio de Janeiro (Figure 8C). Additionally remarkable are the Dracaena draco, Ficus sycomorus and Afrocarpus mannii, among others, e.g., [18].

Figure 8.

The iconic specimens of JBT: (A) Ficus macrophylla, one of the most exuberant specimens in the garden and in Europe; (B) Yucca gigantea, one of the JBT oldest specimens; and (C) the main avenue flanked by Washingtonia robusta and Washingtonia filifera, inspired by the Botanical Garden of Rio de Janeiro (Photos A and B: Duarte; Photo C: Cunha).

3. Discussion

3.1. Natural and Historical Heritage of the Botanical Gardens of Lisbon

The three Botanical Gardens of Lisbon represent an invaluable legacy, and their different scientific and educational roles reflect on their plant collections. Over the centuries, Lisbon’s climate has allowed the coexistence of plant species from many different biogeographical origins, which greatly diversified its gardens. This survey of the tree species (sensu lato) present at the three botanical gardens highlighted that the diversity and tree richness of each garden is linked with its historical background. Despite their different ages and histories, the three Botanical Gardens of Lisbon share the same purposes: research, education, and conservation. Their value goes far beyond their roles as simple gardens, as they can contribute to urban forestry and resilient landscapes, to support and advance urban agriculture, and to conserve urban biodiversity [19].

Although the diversity of species might be expected to depend on the area of the garden due to the potentially higher availability of space and/or of varied habitat types [20], this was not clear in our study. In fact, species diversity can also reflect the development of each garden over time, as well as socioeconomic issues, taking the human and financial resources allocated to garden management into account [21]. In the case of the Botanical Gardens of Lisbon, the historical background and, in particular, the specific mission of each garden cannot be disregarded when trying to understand the existing living collections.

The role of JBA was particularly relevant in the late 18th century as a sponsor of the “Philosophical Journeys”, the first scientific expeditions to the Portuguese territories overseas [22]. Later, the importance of this garden and of its plant collection decreased in favor of JBL, created in the late 19th century to support teaching at the Polytechnic School.

Standing out as a support for botany learning [23] and well-adjusted to the site and the mild climate of the city, the Lisbon Botanical Garden (JBL) holds the most diverse collection (ca. 334 taxa) of the three studied gardens, in terms of both species and geographic origins (see Figure 5). In the heart of Lisbon, it constitutes a reference in urban biodiversity.

Created in the early 20th century, the Tropical Botanical Garden (JBT) is noteworthy for its exotic and economically valuable plants (e.g., spices, fruits, medicinal, stimulants, and ornamentals) especially from tropical and subtropical regions [18,24], related to the educational role in the study of Tropical Agriculture and the introduction of economic and exotic plants [25]. The importance of JBT in this context was made clear in 1940, when it hosted the “Colonial Section of the Portuguese World Exhibition”. Nowadays it allows the general public contact with the tropical sciences, thus contributing to promoting scientific culture among the Community of Portuguese Speaking Countries [26].

Comparing the diversity of species that occur in the three Botanical Gardens of Lisbon, some trees stand out for their biological and iconic character; such are the cases of Ginkgo biloba, the only representative of the Ginkgoaceae family at present [27] and considered a relict taxon dating from the early Jurassic period, a most well-represented species in botanical gardens worldwide [10], and of the Vulnerable Dracaena draco, the most emblematic tree of the Macaronesian region, where it is endemic. Its exuberant growth-form (i.e., arborescent and pachycaulous) and its red resin, known as “dragon’s blood”, are of great interest both at the ornamental and ethnobotanical levels, and the species is widely cultivated despite its rarity in the wild, e.g., [28]. The Endangered Sequoia sempervirens, native to the Pacific coast of the USA, and the only surviving species of the Sequoia genus [29], is found in the collections of JBL and JBT; and the Critically Endangered Metasequoia glyptostroboides, found only in JBL, is also a relict taxon, endemic from a very restricted region of central China [30], and the second best-represented tree species in botanical gardens worldwide [10] where it is successfully cultivated, although the environmental requirements in the wild remain poorly known [31].

The historical imprint is clear in the collections of the three Botanical Gardens of Lisbon. For example, 11% of taxa are from the Afrotropical biogeographic region, reflecting the Portuguese colonization of some very floristic-rich African regions (e.g., Angola or Mozambique) [32]. Whereas Palearctic species are dominant in JBA and JBL, the distinctive tropical character prevails in JBT. The numerous fruit trees from South America (namely Brazil), as well as the numerous useful species of Asiatic origin, account for these values. The flora of south-western Indian Ocean territories (Australia, New Guinea and New Zealand) is the least represented, except for the typical presence, in all the gardens, of some Australotemperate elements, including species of the genera Araucaria, Brachychiton, Eucalyptus, Ficus, and Melaleuca.

The introduction and acclimatization of new exotic plant species in Lisbon, from different geographical regions and with economic and ornamental interest, were not restricted to the botanical gardens. In fact, private gardens also played important roles in the dissemination of such plants, and the taste for these botanic “novelties” was transposed to the streets and public gardens of Lisbon. Private gardens, such as the Parque Monteiro-Mor and Tapada das Necessidades (both from the 18th century), have played a prominent role in the dissemination of such plants through “art” and supported by landscape gardeners, horticulturists, and nurseries.

Additionally, the consort King Ferdinand of Saxe-Coburg and Gotha (1816–1885) brought German romanticism to Portugal. With his collecting spirit and botanic taste and a new way of thinking about gardens, he played an important role in the introduction of exotic ornamental plants [33]. The king’s concern for public gardens was constant, offering plants and even the services of his French gardener Bonnard.

Since the middle of 19th century, the interest for “novelties” was spread to street trees and other Lisbon’s public gardens (e.g., Jardim da Estrela (1852), Jardim do Príncipe Real (1869), Jardim de S. Pedro de Alcântara (1864)). Plants such as Dracaena draco, Ginkgo biloba, Jacaranda mimosifolia, or Araucaria spp., were exhibited in streets and gardens, and some of them remain today. Particularly, Araucaria spp. are majestic trees very appreciated in Portuguese gardens, with the emblematic examples of A. angustifolia, A. bidwilli, A. cunninghamii, and A. heterophylla standing out. Of these, A. angustifolia and A. heterophylla are in risk of extinction and are therefore categorized as CR and VU, respectively (see Table 1). Although A. angustifolia has been cultivated in the South American rainforests since ancient times [34] and indigenous population use their seeds for food and religious rituals [35], the Araucaria forests are compromised due to overexploitation of timber, aggravated by deforestation for agriculture and urbanism. As a consequence, a large part of the native range of A. angustifolia was eliminated, and only a residual part remains, about 15% [36].

Botanical gardens make a significant contribution to the ex situ conservation of wild species, and, particularly for the most threatened trees; their presence should be ensured in several ex situ collections, to widen genetic diversity and thereby increase their conservation value [37]. Of the 22 threatened tree species worldwide most frequently represented in ex situ collections [10], nine can be found in the Botanical Gardens of Lisbon, namely: in the three gardens—Ginkgo biloba (EN), and Beaucarnea recurvata (CR)—in two of the gardens—Sequoia sempervirens (EN), and Cedrus atlantica (EN)—or only in one of the gardens—Metasequoia glyptostroboides (EN), and Abies pinsapo (EN). According to Rivers et al. [10], the family with the highest proportion of threatened species in ex situ collections is the Arecaceae (palm trees, 77%). In the Botanical Gardens of Lisbon, the Arecaceae is also the family with the highest number of threatened taxa—Brahea edulis (EN), Butia eriospatha (VU), Howea forsteriana (VU), and Sabal bermudana (EN).

Most of these species are tropical species, which might indicate their adaptation and resilience to the Mediterranean climate of Lisbon [14]. However, and although emblematic tropical palms, such as Washingtonia robusta (the most dominant palm species overall), are well adapted in the three gardens, it is crucial to monitor those more vulnerable to the pests and diseases which recently reduced the abundance of some palm species [38]. For instance, the Coleopteran Rhynchophorus ferrugineus (Olivier) is a pest of Phoenix dactylifera and Phoenix canariensis, e.g., [39], which are present in all the Botanical Gardens of Lisbon.

3.2. Outreach and Education Programs

Located in the strategic and most touristic area of Lisbon (Belém), JBT receives the highest number of visitors among the three Botanical Gardens of Lisbon (140,000 in 2018). In all the three gardens, plant diversity and conservation are the focus of the programs targeting families and general audiences, and they maintain extension and outreach programs, sometimes with the support of the civil society. Guided tours show the botanical collection as well as the historic, artistic, and cultural heritage enclosed in these spaces. Educational activities for school groups and teachers are also proposed, and training courses for touristic guides and gardening courses are regularly organized. Scientific activities are offered year-round, namely in events such as the European Researchers’ Night, sponsored by the European Commission. JBT recently launched a freely available mobile application with interactive maps (e.g., “Trees you must see”, “Garden with History”, “Birds”, and “Biosensors”) offering augmented reality experiences to the visitors. JBL offers twilight visits, whereas JBA promotes cultural activities such as theatre for children. The three Botanical Gardens of Lisbon are part of the “European Route of Historic Gardens”, certified as one of the forty “Cultural Routes of the Council of Europe”.

The future of the botanical gardens, as spaces of knowledge about the plant world, will certainly depend on the reinforcement of research, education and cultural activities. This, in turn, requires the continuous and careful maintenance of the botanical heritage of these living museums. Accordingly, the three Botanical Gardens of Lisbon are expected to: (i) enhance the visibility of their collections and heritage, and to strengthen bonds, partnerships and joint work between different collections; (ii) manage biological collections using modern software; (iii) create a DNA Bank associated to the collections; (iv) disseminate results to the scientific community, and promote innovative education actions and seminars; and (v) promote ex situ conservation initiatives, including maintenance of the seed bank and identification of living collections of rare and threatened species, particularly from the Portuguese flora.

3.3. Final Remarks

All the green areas of Lisbon constitute a very important heritage for our ex situ plant diversity conservation, however, the Botanical Gardens of Lisbon must be seen as unique spaces for tree conservation and their articulation with the surroundings, in ecological, aesthetic, cultural, historical, social, and economic terms, is fundamental to the urbanized space of Lisbon [14].

The preservation of trees, as well as of green urban areas which encompass the botanical gardens, is a current purpose aiming at making cities more resilient to climate change [40,41]. This was one of the main objectives of the “European Green Capital 2020” for Lisbon [42], promoting sustainability, biodiversity, and preservation of threatened species; it should also be a common goal to all cities, since more than half of the world’s population currently lives in cities and predictions indicate that more than two thirds will live there by 2050 [43].

In this context, botanical gardens play a very important role in urban sustainability: adding to botanical knowledge, they also store years of practice in horticulture and arboriculture, which is extremely useful to improve urban green spaces in fields such as tree selection and planting, urban forest management plans and restoration [4]. Furthermore, this kind of knowledge can help in the implementation of sustainable environmental management practices, urban biodiversity [44], and the maintenance of urban trees [45], as well as to promote ecosystem services, preserving and valuing biodiversity [46].

4. Materials and Methods

4.1. Studied Areas

The three Botanical Gardens of Lisbon (JBA—Botanical Garden of Ajuda; JBL—Lisbon Botanical Garden; and JBT—Tropical Botanical Garden) are characterized in Table 2, and their location in Lisbon (see Figure 1).

Table 2.

General characterization of each garden of Lisbon (JBA—Botanical Garden of Ajuda; JBL—Lisbon Botanical Garden; and JBT—Tropical Botanical Garden).

Characteristics	JBA	JBL	JBT
Year of creation	1764	1837	1906
Year of inauguration	1768	1878	1914 *
Location	western Lisbon/Ajuda	Central Lisbon	western Lisbon/Belém
Coordinates (latitude/longitude)	38.706205/−9.199421	38.717429/−9.150306	38.698140/−9.203913
Elevation	70–80 m	37–77 m	10–35 m
Area (green spaces)	3.8 ha	5.6 ha	6.4 ha

* Corresponds to inauguration date in current location, at Belém.

4.1.1. Botanical Garden of Ajuda (JBA)

JBA is located in Calçada da Ajuda (Figure 1) opposite to the Palácio Nacional da Ajuda and is the oldest Botanical Garden in Portugal. It was established on two terraces, separated by a limestone balustrade, and connected by a central and two lateral staircases authored by the architect Manuel Caetano de Sousa (1730–1802). The upper terrace hosts the botanical collection, and the lower terrace is composed of a central fountain and 4 km of hedges of boxwood and myrtle, in geometric forms around basins and sculptures from the stone’s school of Machado de Castro (1731–1822), possibly conceived as a recreation space for the royal family. JBA combines several styles and epochs, with a predominant line of baroque influence [47].

4.1.2. Lisbon Botanical Garden (JBL)

JBL is located in the center of Lisbon (Figure 1) and occupies the core of the block bordered by the main avenue (Avenida da Liberdade) and a large garden square (Jardim do Príncipe Real). It is structured in two parts, the “Class” and the “Arboretum” [48,49]. The “Class” develops at the same level as the main building of the National Museum of Natural History and Science/University of Lisbon; the “Arboretum” extends downwards the slope, as an organic composition of flowerbeds, streams, waterfalls, lakes, and passages, surrounded by a pathway [50].

4.1.3. Tropical Botanical Garden (JBT)

JBT is situated in the monumental area of Lisbon, next to Mosteiro dos Jerónimos and to the Palácio de Belém and covers 800 m along a south-facing hill slope, overlooking the Tagus River (Figure 1). Favored by a privileged microclimate, JBT has plenty of water and has been enriched with a great diversity of exotic plant species. JBT encloses historical buildings such as the Palace of Condes da Calheta (17th century), and marble sculptures of different aesthetic concepts that span over several historical periods, from the 17th to the 20th centuries [18].

4.2. Historical Data

The historic framework of the three botanical gardens was retrieved from several types of documents, such as the descriptions of the scientific expeditions performed in the late 18th century in the Portuguese territories overseas, the so-called “Philosophical Journeys” [22,49], and other historical documents with descriptions and information referring to their history, e.g., [18,23,24,45,47,48,49,51,52,53,54,55,56,57,58,59,60,61].

4.3. Tree Layer Inventory

The surveys in the three botanical gardens focused on tree specimens and were carried out in the framework of the “LX GARDENS” research project (2014–2017, targeting Lisbon’s historic gardens). The following methodology was used for the botanical study: inventory, location (with geographic information systems) and specimen identification. All data were recorded in a relational database built on a SQL server. Location data recorded included the following items: (1) Specimen ID number; (2) Garden code; (3) Species code; (4) Family; (5) Species; (6) Species classifier; (7) Geographic origin of the taxon; (8) Naturality Status in Portugal (i.e., native, non-native and/or invasive); (9) Growth form (meaning the plant’s physiognomy); (10) ETRS 1989 coordinates; (11) Extinction risk assessment using the IUCN Red List [12]. The data of the three botanical gardens were continuously updated until May 2021.

Tree species were chosen for the study due to their perenniality and longevity, which seemed appropriate and important traits for the intended historical approach. Tree definition followed the one proposed by the IUCN’s Global Tree Specialist Group (GTSG): “a woody plant with usually a single stem growing to a height of at least 2 m, or if multi-stemmed, then at least one vertical stem 5 cm in diameter at breast height”. Several habit types were considered: trees sensu stricto, shrubs, rosette trees, and stem-succulents. For simplicity, all these types are here considered, in a broad sense, as “trees”, and belonging to the “tree layer” of the gardens. To support species selection, the GlobalTreeSearch [15] was also consulted.

Species identification or validation was made using specialized bibliography, e.g., [62,63,64,65,66,67,68,69,70,71,72] and specimens housed at the João Carvalho e Vasconcellos herbarium (LISI)/Instituto Superior de Agronomia (University of Lisbon). Scientific names and families mainly follow Plants of the World Online [73] and the World Flora online [74].

4.4. Database of the Tree Layers

Plant data of each Lisbon botanical garden, including species names, families, growth form, and native distribution, are summarized in Table 1. The native distribution follows Morrone’s [75] Biogeographical Regions (i.e., Afrotemperate, Afrotropical, Andean, Australotemperate, Australotropical, Nearctic, Neoguinean, Neotropical, Neozelandic, Oriental, and Palearctic) and online databases, namely the Plants of the World Online [73] and the GBIF platform [76]. The conservation status of each species was retrieved from the IUCN Red List of Threatened Species [12].

4.5. Data Treatment

All analyses were carried out in the RStudio program version 1.1.456 [77]. In order to detect the diversity patterns of the tree layers of the three Botanical Gardens of Lisbon, the following analyses were performed: scatter pie plot, Euler diagram, and heatmap. All the plots were visualized by ggplot2 [78].

Author Contributions

Conceptualization, M.M.R. and A.L.S.; formal analysis, M.B. and A.R.C.; data inventories, A.L.S., A.R.C., T.V., P.A., D.E.-S. and M.C.D.; validation, A.L.S., D.E.-S. and M.C.D.; writing—original draft preparation, M.M.R.; writing—review and editing, M.M.R., A.L.S., A.R.C., M.B. and M.C.D.; supervision, M.M.R. and A.L.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Foundation for Science and Technology (FCT) of the Portuguese Government through the project “LX GARDENS—Lisbon’s Historic Gardens and Parks: Study and Landscape Heritage Inventory” (PTDC/EAT-EAT/110826/2009). Fellowships to A.R.C. (2020/04824/BD) and to M.B. (UI/BD/151188/2021) were funded by FCT. Also to research units: UIDB/04129/2020 to Linking Landscape, Environment, Agriculture and Food (LEAF), UIDB/50027/2020 to Research Centre in Biodiversity and Genetic Resources, and UID/BIA/00329/2021 to Centre for Ecology, Evolution and Environmental Changes (cE3c). The Open Access was funded by national funds through FCT I.P., in the scope of the project “Rede de Investigação em Biodiversidade e Biologia Evolutiva” UIDB/50027/2020.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

We confirm that all data are original and provided in Tables and Figures within the article.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.