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. 2022 Nov 28;11(23):3273. doi: 10.3390/plants11233273

Tendril Anatomy: A Tool for Correct Identification among Cucurbitaceous Taxa

Naveed Abbas 1, Muhammad Zafar 1,*, Mushtaq Ahmad 1,2, Ashwaq T Althobaiti 3, Mohamed Fawzy Ramadan 4, Trobjon Makhkamov 5, Yusufjon Gafforov 6,7, Khislat Khaydarov 8, Muhammad Kabir 9, Shazia Sultana 1, Salman Majeed 1,10, Tajalla Batool 1
Editors: Ioannis Bazos, Kostas Kougioumoutzis, Panayotis Dimopoulos
PMCID: PMC9735582  PMID: 36501313

Abstract

This research examined the histological micro-structure of tendril vasculature in cucurbitaceous taxa. In this research, the tendril anatomy of 17 taxa of Cucurbitaceae categorized into seven genera, including Cucumis (five species), Cucurbita and Luffa (three species each), Citrullus and Momordica (two species each) while Lagenaria and Praecitrullus (one species each), collected from different areas of the Thal desert were examined via microscopic imaging to explore its taxonomic significance. Tendril transverse sections were cut with a Shandon Microtome to prepare slides. The distinctive characteristics of taxonomic value (qualitative and quantitative) include tendril and vascular bundle shape, variation in the number of vascular bundles, tendril diameter length, layers of sclerenchyma, and shape of collenchyma and epidermal cells. Tendril shapes observed are irregular, slightly oval-shaped, slightly C shaped, angular (4-angled, 6-angled, or polygonal), and star shaped. Quantitative measurements were taken to analyze the data statistically using SPSS software. Cucurbita pepo had a maximum tendril diameter length of 656.1 µm and a minimum in Momordica balsamina of 123.05 µm. The highest number of vascular bundles (12) were noticed in Luffa acutangula var.amara. Angular type was prominent in collenchyma, and irregular shape was dominant in sclerenchyma cells. A maximum of seven to nine sclerenchyma layers were present in Lagenaria siceraria and a minimum of two or three layers in Cucumis melo subsp. agrestis, Cucumis melo var. flexuosus, and Cucumis melo var.cantalupensis. Epidermis cells also show great variations with a rectangular shape being dominant. Statistical UPGMA dendrogram clustering of tendril vasculature traits shows that histological sections studied with microscopic techniques can be used to identify species and will play a vital role in future taxonomic and phylogenic linkages.

Keywords: anatomy, Cucurbitaceae, micromorphology, Parenchyma, vessel elements

1. Introduction

The Cucurbitaceae family, or cucurbits, are most widely distributed in subtropical and tropical climates, with hotspots in West Africa, Southeast Asia, Mexico, and Madagascar [1]. Cucurbitaceous members (watermelons, cucumbers, luffas, pumpkin, courgettes, zucchini, and summer squash) are all edible and can be found growing across all continents. Around 800 species and 130 genera can be distributed worldwide [2]. In West Africa, this family is represented by 24 genera and 54 species [3]. In Pakistan, it has 33 species across 17 genera, including both domesticated (22 species) and wild species (11 species) [4]. The wild genera are Coccinia, Lageneria, Luffa, Momordica, and Zehneria, whereas cultivated include Citrullus, Cucumis, Cucurbita, Cucumeropsis, Lagenaria, Telfairia, and Trichosanthes [4]. However, Pakistan’s cucurbit species with high nutritious potential remain unexplored [5].

Citrullus lanatus is a succulent species belonging to the Citrullus genus and are desert vines and the only genus in the family with pinnatifid leaves. Watermelon (three varieties) and brown-seeded melon, both with bitter pulp, are members with solitary staminate flowers, tiny sepals, a basal corolla sectioned into five parts, and fleshy fruits. These are members of the subspecies C. lanatus, which is commonly cultivated in Pakistan. Cucumis, true melons, honey melons, and West Indian gherkins are all members of the twinning, tendril-bearing plants that belong to the Cucumis genus [6]. The leaves rarely split beyond the center. The fruits are smooth, green-lined, or hairy, with the appearance of a ground trailer. Cucurbita is a genus with approximately 20 species. The primary cultivated squash and pumpkin are four different Cucurbita species: C. pepo, C. sativus, C. maxima, and C. pepo var cylindrica. Ripe and immature fruit is the most important edible plant parts, although some species also consume seeds, flowers, roots, and even leaves. Cucurbitaceous species are not the only source of food, but are also used as a nutraceutical and pharmacotherapeutic potential [7]. The pepo’s sweet, delicately flavored, juicy flesh is eaten raw, frequently as a dessert. Cucumis melo, often known as sweet melon, is a fruit, not a vegetable.

Cucurbitaceous family members have lianous plant bodies, peculiar fleshy fruits (known as pepo), and a similar system of sex determination. The Cucurbitaceous species are primarily herbaceous plants with diverse pubescence and tuberous roots [2,8]. They are also physically distinguished by frequently angled stems and bicollateral vascular bundles that are frequently grouped in two concentric rings. The leaves are petiolate, exstipulate, alternating, often palmately veined, simple, or sedately complex, with extra-floral nectaries. The tendrils are lateral to the base of the petiole, usually one to four at each node, branching, simple-lobed, with a non-spiraling base [4].

Tendrils are an excellent example of convergent evolution because they have evolved numerous times among angiosperms. They can be found in lineages that are not closely related, such as Magnoliales and Asterales [9]. Tendrils are a perfect demonstration of their wide variation in morphology and ontogeny over the course of evolution. Tendrils can develop from modified twigs, pedicel, stipules, entire leaves, leaflets, leaf bracts, leaf apex, and inflorescences [10].

Environmental changes do not affect a plant’s anatomical characteristics [11]. Anatomical information was utilized to identify plant species, genera, and families. It is frequently employed in systematic identification, giving anomalous groupings a better classification position and illuminating relationship patterns that morphological traits may not have entirely conveyed. Nevertheless, it has been documented that cucurbit species in Pakistan can be distinguished by their plant morphology and anatomy [3]. Several [12,13,14] researchers describe anatomical characters of Cucurbitaceous species however, tendril micromorphology is not visualized [15]. Plant cell and tissue distributions such as sclerenchyma, vascular bundles, and other anatomic traits have been described at various systematic levels for species delimitation [16]. The presence of trichomes on the lower surface of the leaves, which reflects significant taxonomic relevance, is well recognized in the Cucurbitaceae [17]. Comparative and systematic studies on the anatomy of the various vegetative organs (root, stem, and leaf) of the species of the Cucurbitaceae family were carried out [13,14,18,19].

Thus, to better understand the systematic relationships, there is a need to study different field characteristics, like the anatomical features of tendrils involved in plant taxonomy. This study aimed to analyze and describe the significant tendril micromorphological traits which will contribute to the anatomy of the Cucurbitaceae and provide features for accurate species identification and their taxonomic implications.

2. Results

Tendril anatomical traits observed in the current investigation were outline, vascularization forms, vessel elements, collenchyma, chlorenchyma, sclerenchyma, as well as parenchyma tissues as illustrated (Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8 and Figure 9). The summarized qualitative and quantitative results are given in (Table 1, Table 2, Table 3 and Table 4). Observing their recorded taxonomic evaluation, cucurbitaceous taxa showed significant size and shape variation (Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8 and Figure 9).

Table 1.

Qualitative tendril anatomical characters of Cucurbitaceous species.

Sr No. Cucurbitaceous Taxa Epidermal Cell Shape Collenchyma Cell Type Chlorenchyma Cell Shape Sclerenchyma Cell Shape Parenchyma Cell Shape Vascular Bundle Shape Vascular Bundles Tendril Outline in Transverse View
1. Citrullus colocynthis (L) Schrad. Rectangular and isodiametric Angular Rectangular to irregular Tetragonal to polygonal Polygonal Oval Subsidiary Slightly oval
2. Citrullus lanatus (Thunb.) Matsum.& Nakai Rectangular Angular Irregular Polygonal to irregular Irregular Elliptical Subsidiary Irregular, slightly v shaped
3. Cucumis melo L. Rectangular Angular Irregular Irregular Irregular Irregular Subsidiary Irregular shaped
4. Cucumis melo subsp. agrestis (Naudin) Pangalo Oval to irregular Angular Irregular Polygonal Polygonal Irregular Subsidiary 4 angled
5. Cucumis melo var. flexuosus (L.) Naudin Rectangular, square, and isodiametric Angular Irregular Tetragonal to polygonal Polygonal Irregular Subsidiary Irregular shaped
6. Cucumis melo var.cantalupensis Naudin Rectangular to square Angular Polygonal Triangular to polygonal Irregular Irregular Central Irregular shaped
7. Cucumis sativus L. Rectangular Angular Rectangular Tetragonal to polygonal Irregular Elliptical and irregular Subsidiary Star-shaped
8. Cucurbita maxima Duchesne Rectangular Angular Rectangular to polygonal Irregular Irregular Dumbbell and irregular Subsidiary Irregular shaped
9. Cucurbita pepo L. Rectangular to square Lamellar and angular Polygonal Irregular Irregular Irregular Subsidiary Six angled
10. Cucurbita pepo var. cylindrica Rectangular, square to polygonal Lamellar and angular Polygonal Irregular Irregular Oval and irregular Subsidiary Slightly c shaped
11. Lagenaria siceraria (Molina) Standl. Rectangular Lamellar Rectangular to irregular Irregular Irregular Rounded Subsidiary Irregular with hollow pith
12. Luffa acutangula (L.) Roxb. Irregular Angular Irregular Irregular Irregular Rounded Subsidiary Irregular with hollow pith
13. Luffa acutangula var. amara C.B.Clarke Rectangular, square to polygonal Angular Polygonal Polygonal and irregular Irregular Round and oval Subsidiary Irregular polygonal
14. Luffa cylindrica (L) M.Roem Rectangular to square Angular Hexagonal to polygonal Tetragonal to polygonal Irregular Round and elliptical Subsidiary Six angled
15. Momordica charantia L. Rectangular to irregular Angular Pentagonal to polygonal Irregular Irregular Rounded and elliptical Subsidiary 4 angled
16 Momordica balsamina L. Pentagonal to hexagonal Angular Rectangular to polygonal Tetragonal to hexagonal Pentagonal to irregular Oval and irregular Central 4 angled
17 Praecitrullus fistulosus (Stocks) Pangalo Rectangular Angular Pentagonal to polygonal Irregular Irregular Irregular Subsidiary Polygonal, slightly U shaped
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Table 2.

Quantitative analysis of tendril anatomy of Cucurbitaceous taxa.

Sr No. Cucurbitaceous Taxa No. Of Vascular Bundles Epidermal Cell Layer Collenchyma Cell Layer Chlorenchyma Cell Layer Sclerenchyma Cell Layer Parenchyma Cell Layer Vessel Elements
1. Citrullus colocynthis (L) Schrad. 4 1 3–4 1–2 3–5 4 6
2. Citrullus lanatus (Thunb.) Matsum.& Nakai 6 1 2–3 1 3–4 4 5
3. Cucumis melo L. 5 1 3 1 3 4 8
4. Cucumis melo subsp. agrestis (Naudin) Pangalo 5 1 3 1–2 2–3 4 8
5. Cucumis melo var. flexuosus (L.) Naudin 7 1 3 2 2–3 3 5
6. Cucumis melo var.cantalupensis Naudin 6 1 3 2 2–3 4 4
7. Cucumis sativus L. 5 1 4 1 2–4 6 15
8. Cucurbita maxima Duchesne 7 1 3 2 5 4 9
9. Cucurbita pepo L. 6 1 6 2 3–4 4 7
10. Cucurbita pepo var. cylindrica 7 1 4 2 3–4 3 9
11. Lagenaria siceraria (Molina) Standl. 7 1 3–4 2–3 7–9 5 8
12. Luffa acutangula (L.) Roxb. 8 1 5 1 6–8 3 8
13. Luffa acutangula var.amara C.B.Clarke 12 1 6 2 6 2 9
14. Luffa cylindrica (L) M.Roem 8 1 5 1 6 3 9
15. Momordica charantia L. 7 1 5 1 4 3 9
16 Momordica balsamina L. 3 1 3–5 1 1 3–4 10
17 Praecitrullus fistulosus (Stocks) Pangalo 10 1 2–5 2 4 5 5
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Table 3.

Quantitative tendril anatomical data of Cucurbitaceous species.

Sr No. Cucurbitaceous taxa L x W Tendril Diameter (µm) Upper Epidermal Cell (µm) Lower Epidermis Cell (µm) Collenchyma Cell (µm)
1. Citrullus colocynthis (L) Schrad. L 314 − 326.25 = 321.65 ± 5.02 16.75 − 23.25 = 19.85 ± 2.57 16.75 − 22.50 = 19.65 ± 2.25 10.50 − 21.25 = 16.80 ± 4.74
W 297 − 304.75 = 301.10 ± 2.77 12.25 − 17.75 = 14.95 ± 2.13 12.75 − 18 = 15.10 ± 2.19 4.25 − 16.75 = 11 ± 4.72
2. Citrullus lanatus (Thunb.) Matsum.& Nakai L 512.50 − 517.75 = 514.95 ± 2.18 15.75 − 25.25 = 20.90 ± 3.75 14.75 − 25.75 = 20.55 ± 4.93 16.25 − 23.25 = 19.80 ± 2.56
W 250 − 258.75 = 253.50 ± 3.24 10 − 20 = 12.9 ± 4.14 10.25 − 20.50 = 13.55 ± 4.12 7.50 − 12.50 = 10.05 ± 1.97
3. Cucumis melo L. L 126.75 − 145.25 = 134.10 ± 7.44 10.50 − 21.75 = 16.20 ± 4.50833 10 − 20.75 = 15.55 ± 4.28442 12.00 − 21.25 = 16.20 ± 3.77
W 122.75 − 138 = 130 ± 6.38 8.75 − 13.75 = 11.05 ± 2.07 8.75 − 13 = 10.6 ± 1.85 7.50 − 13.75 = 10.65 ± 2.75
4. Cucumis melo subsp. agrestis (Naudin) Pangalo L 200.50 − 212.50 = 205.35 ± 5 3.75 − 25.50 = 16.70 ± 9.13 4.75 − 25.50 = 12.85 ± 9.49 13.00 − 35.50 = 25.50 ± 9.78
W 183.50 − 188.50 = 186.30 ± 2.13 3.75 − 18 = 11.55 ± 6.18 2.50 − 15.25 = 7.25 ± 4.97 8.25 − 25.50 = 15.45 ± 6.54
5. Cucumis melo var. flexuosus (L.) Naudin L 325.25 − 333 = 328.85 ± 3.18 13 − 50.25 = 23.15 ± 15.28 13.50 − 45.25 = 22.50 ± 12.90 11 − 28 = 18.50 ± 6.98
W 250.25 − 267.75 = 257.30 ± 7.73 7.75 − 16.75 = 11.15 ± 3.81 8 − 14.25 = 10.75 ± 2.97 2.75 − 13.25 = 8.5 ± 3.83813
6. Cucumis melo var.cantalupensis Naudin L 250.50 − 256.50 = 253.75 ± 2.384 18.75 − 26.25 = 22.7500 ± ± 2.87 19.50 − 26.50 = 22.6500 ± 2.831 13.00 − 24.75 = 18.7000 ± 4.396
W 225 − 231.25 = 227.60 ± 2.36 13.75 − 23.25 = 18.20 ± 3.40221 13.25 − 19.50 = 16.70 ± 2.558 12 − 14.25 = 13.1500 ± 0.91
7. Cucumis sativus L. L 524.75 − 531.25 = 527.40 ± 2.71 20.75 − 30.00 = 26.0500 ± 4.052 17.75 − 30.50 = 25.9500 ± 5.7047 23.25 − 33.50 = 27.8500 ± 3.7358
W 225.00 − 238.25 = 229.40 ± 5.375 10.25 − 13.00 = 11.5500 ± 1.242 10.25 − 13.00 = 11.5500 ± 1.267 13.75 − 21.25 = 17.7000 ± 2.808
8. Cucurbita maxima Duchesne L 589.75 − 600.25 = 595.60 ± 3.9115 19.25 − 42.25 = 27.3000 ± 10.24 19.50 − 41.00 = 27.2000 ± 9.8256 12.25 − 20.00 = 16.8500 ± 3.5820
W 486.25 − 494.75 = 489.60 ± 3.3241 9.25 − 20.00 = 14.2500 ± 4.10 9.75 − 19.75 = 14.4000 ± 3.91152 8.75 − 13.25 = 10.7000 ± 1.68077
9. Cucurbita pepo L. L 650.00 − 662.75 = 656.10 ± 4.735 8.75 − 19.75 = 13.9000 ± 4.211 8.00 − 20.00 = 13.5000 ± 4.53114 9.50 − 15.25 = 12.8500 ± 2.29538
W 315.50 − 321.25 = 317.60 ± 2.1837 7.50 − 17.50 = 11.4500 ± 3.8786 7.25 − 18.00 = 11.3000 ± 4.298 7.25 − 14.75 = 10.4500 ± 3.0893
10. Cucurbita pepo var. cylindrica L 361.25 − 368.00 = 364.45 ± 2.6774 22.50 − 31.25 = 26.5000 ± 3.579 22.75 − 31.00 = 26.5500 ± 3.188 16.75 − 25.00 = 21.7500 ± 3.292
W 162.75 − 170.25 = 1.67.00 ± 2.93 13.00 − 22.50 = 18.0500 ± 3.692 13.25 − 22.00 = 18.0000 ± 3.592 10.50 − 19.25 = 14.8500 ± 3.223
11. Lagenaria siceraria (Molina) Standl. L 471.25 − 487.75 = 477.85 ± 6.125 14.50 − 27.50 = 20.4500 ± 5.874 14.25 − 27.75 = 20.7000 ± 6.2759 22.50 − 30.50 = 27.7500 ± 3.172
W 210.00 − 223.75 = 217.65 ± 5.641 9.75 − 13.00 = 11.1000 ± 1.526 9.50 − 13.00 = 11.1500 ± 1.61632 8.75 − 12.75 = 10.7000 ± 1.71756
12. Luffa acutangula (L.) Roxb. L 250 − 676.25 = 582.85 ± 186.37 8.50 − 20.50 = 15.05 ± 4.56002 7.25 − 20.50 = 14.7 ± 5.03550 13.00 − 28.50 = 21.20 ± 6.13
W 251.75 − 270.25 = 258.85 ± 7.86 5.25 − 10.50 = 8.05 ± 1.89 5.00 − 10.25 = 7.75 ± 1.87 7.50 − 17.50 = 12.20 ± 3.7
13. Luffa acutangula var.amara C.B.Clarke L 451.25 − 480.50 = 472.45 ± 11.99 17.50 − 26 = 21.05 ± 4.19 17.75 − 27.50 = 21.3 ± 4.8 15.50 − 25 = 20.30 ± 3.83
W 219.75 − 252.75 = 229.20 ± 13.64 12.50 − 17 = 14.4 ± 1.82 12.75 − 16.25 = 4.1 ± 1.47479 12.75 − 22.75 = 15.9500 ± 3.98
14. Luffa cylindrica (L) M.Roem L 401.25 − 413.75 = 406.2 ± 4.84897 11.25 − 15.75 = 13.0000 ± 1.677 11.50 − 15.75 = 13.0000 ± 1.6488 15.75 − 23.25 = 19.7000 ± 3.2948
W 172.25 − 180.25 = 175.75 ± 2.915 8.00 − 15.25 = 11.6500 ± 2.637 8.25 − 15.25 = 11.7000 ± 2.51496 13.00 − 18.00 = 15.0500 ± 2.041
15. Momordica charantia L. L 350.00 − 357.75 = 353.25 ± 3.177 11.75 − 17.00 = 14.7500 ± 2.186 12.00 − 17.00 = 14.6000 ± 2.2262 16.25 − 20.00 = 18.2500 ± 1.3578
W 160.75 − 167.25 = 164.55 ± 2.7064 8.75 − 11.00 = 9.9000 ± 0.96177 9.00 − 10.75 = 9.9500 ± 0.71589 9.25 − 11.75 = 10.5500 ± 1.10962
16 Momordica balsamina L. L 122.25 − 124.0 = 123.05 ± 0.81777 8.75 − 16.25 = 13.3000 ± 2.9811 8.50 − 16.00 = 13.3000 ± 3.15436 14.00 − 25.50 = 19.4500 ± 5.5884
W 112.25 − 114.00 = 112.95 ± 0.64711 7.75 − 12.25 = 10.3000 ± 1.6240 8.00 − 12.00 = 10.3500 ± 1.49583 12.75 − 14.75 = 13.8500 ± 0.89443
17 Praecitrullus fistulosus (Stocks) Pangalo L 575.25 − 584.00 = 578.95 ± 3.49 22.50 − 32.75 = 28.0000 ± 4.172 23.50 − 33.00 = 27.6500 ± 4.207 17.25 − 26.25 = 22.2000 ± 3.858
W 238.00 − 244.75 = 241.90 ± 2.7477 13.00 − 19.25 = 16.2500 ± 2.417 13.25 − 18.75 = 16.1000 ± 2.043 10.50 − 20.00 = 14.6000 ± 3.529
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Table 4.

Quantitative tendril anatomical features among Cucurbitaceous species.

Sr No. Cucurbitaceous taxa L x W Chlorenchyma Cell (µm) Sclerenchyma Cell (µm) Parenchyma Cell (µm) Vessel Elements(µm) Vascular Bundle (µm)
1. Citrullus colocynthis (L) Schrad. L 31.75 − 50.25 = 40.50 ± 7.65 11.25 − 25 = 25 ± 5.76 50.50 − 84.75 = 66.25 ± 15.04 18.00 − 26.25 = 21.70 ± 3.52 135.50 − 188 = 161.55 ± 21.20
W 12.00 − 19.25 = 16.05 ± 3.04 10.50 − 22.25 = 16.10 ± 4.73 47.00 − 77.25 = 63.35 ± 13.40 5.70 − 9.90 = 7.82 ± 1.69 74.25 − 90.75 = 81.40 ± 6.79
2. Citrullus lanatus (Thunb.) Matsum.& Nakai L 16.25 − 27.00 = 21 ± 4.25 10.75 − 27.75 = 22.40 ± 6.76 38.75 − 101 = 74.65 ± 28.14 25.50 − 37.50 = 29.05 ± 4.85 89.50 − 200.25 = 146.15 ± 48.33
W 8.25 − 14.75 = 10.65 ± 2.56 8.50 − 21 = 16.10 ± 4.84 26.25 − 28.75 = 27.35 ± 0.96 15 − 25 = 18.30 ± 4.44 27 − 89.75 = 64.25 ± 29.42
3. Cucumis melo L. L 18.75 − 26.25 = 22.15 ± 2.98 16.75 − 28 = 22.10 ± 4.83 18 − 43.75 = 29 ± 11.15 11.25 − 16.25 = 13.75 ± 2.26 89 − 113.75 = 99.90 ± 10.29
W 8.75 − 11.75 = 10.35 ± 1.23 9.75 − 22 = 14.90 ± 5.23 9.75 − 22 = 14.90 ± 5.23 8.50 − 11.25 = 9.55 ± 1.10 30.50 − 55.25 = 38.20 ± 9.97
4. Cucumis melo subsp. agrestis (Naudin) Pangalo L 15.50 − 25.25 = 20.60 ± 4.05 8.25 − 20.25 = 13.55 ± 4.54 20.50 − 77.75 = 53.55 ± 26.50 9.75 − 13.25 = 11.50 ± 1.47 47.25 − 97 = 74 ± 19.78
W 7.75 − 10.25 = 8.9000 ± 1.24 2.75 − 18.50 = 9 ± 6.02 27.75 − 62.75 = 46.25 ± 13.21 5.25 − 10.25 = 7.90 ± 1.78 22.50 − 33.75 = 28.20 ± 4.25
5. Cucumis melo var. flexuosus (L.) Naudin L 13 − 41.25 = 25.65 ± 10.97 5.25 − 20.50 = 16.15 ± 6.39 23.25 − 112.50 = 61.50 ± 37.46 7.75 − 13.75 = 11.75 ± 2.60 75.25 − 163 = 117.10 ± 39.43
W 10.50 − 20 = 14.35 ± 4.27 3.75 − 15.25 = 10.15 ± 4.71 15.50 − 55.25 = 33.50 ± 14.27 5.50 − 13.25 = 9.60 ± 3.02 26.75 − 51.50 = 42.55 ± 9.86
6. Cucumis melo var.cantalupensis Naudin L 42.00 − 46.25 = 43.80 ± 1.67 19.25 − 25.75 = 21.35 ± 2.61 49.25 − 86.25 = 68.10 ± 13.73 29.75 − 40.75 = 34.95 ± 4.48 77.25 − 106.25 = 89.10 ± 11.14
W 24.50 − 29.50 = 27.45 ± 2.06 10.50 − 14.25 = 12.20 ± 1.47 36.25 − 52.75 = 44.15 ± 6.78 21.25 − 37.75 = 30.45 ± 6.66 26.25 − 37.25 = 30.95 ± 4.10
7. Cucumis sativus L. L 25.50 − 62.75 = 44.25 ± 13.87 10.25 − 30 = 19.05 ± 8.56 13.75 − 88 = 56.95 ± 32.34 38.25 − 47.50 = 42.55 ± 4.09 151.75 − 301.25 = 224.15 ± 56.12
W 13.75 − 20.25 = 17 ± 2.54 7.75 − 20.25 = 14.25 ± 5.60 11.00 − 39.25 = 24.45 ± 10.77 20.50 − 38 = 29.25 ± 7.35 101.50 − 202.25 = 125.30 ± 43.31
8. Cucurbita maxima Duchesne L 20.50 − 51.25 = 33.60 ± 11.74 13.75 − 27.75 = 20.70 ± 5.67 24.75 − 64.50 = 45.15 ± 16.02 24.75 − 43 = 35.10 ± 6.83 30.50 − 38.75 = 34 ± 3.15
W 11.75 − 18 = 13.55 ± 2.60 9.50 − 12.50 = 11.45 ± 1.19 14.50 − 28.25 = 20.80 ± 6.11 18.75 − 27.75 = 22.90 ± 3.92 24.75 − 30.75 = 27.35 ± 2.24
9. Cucurbita pepo L. L 21.75 − 29.25 = 26.60 ± 3.12 20.25 − 30 = 24.05 ± 3.68 30.50 − 66.25 = 53.35 ± 14.31 25.75 − 35.25 = 30.80 ± 3.69 37.25 − 44.50 = 41.55 ± 3.12
W 7.25 − 19.75 = 10.95 ± 5.05 9.75 − 14.25 = 11.25 ± 1.76 17.75 − 50.75 = 30.95 ± 12.30 15.25 − 33.75 = 24.75 ± 8.65 24.50 − 29.50 = 27.55 ± 1.93
10. Cucurbita pepo var. cylindrica L 26.75 − 46.25 = 33.55 ± 7.57 19.50 − 25.25 = 23.05 ± 2.34 47.25 − 98.75 = 63.45 ± 20.67 16.25 − 22.25 = 19 ± 2.34 22.50 − 28.75 = 26.10 ± 2.87
W 12.50 − 28 = 19.10 ± 7.40 12.25 − 18 = 16.35 ± 2.32 12.25 − 25 = 18.45 ± 5.13 11.25 − 15 = 13.30 ± 1.52 17.25 − 21.25 = 19.35 ± 1.51
11. Lagenaria siceraria (Molina) Standl. L 20 − 46.25 = 32.50 ± 10.08 22.50 − 31.25 = 27.60 ± 3.43 43.75 − 105.25 = 74.15 ± 22.10 20 − 37.50 = 28.30 ± 7.28 63.25 − 103.75 = 86.25 ± 17.20
W 11.75 − 17.50 = 13.40 ± 2.38 11.75 − 20.25 = 15.05 ± 3.65 26.75 − 36.50 = 31.40 ± 4.32 18 − 30.75 = 24.80 ± 5.14 25.50 − 63.50 = 38.95 ± 14.65
12. Luffa acutangula (L.)Roxb. L 17.75 − 45.50 = 30.50 ± 10.42 15.75 − 35.75 = 26.70 ± 8.98 24.25 − 38.75 = 31 ± 5.76086 25.50 − 32.75 = 27.60 ± 3.04 76.25 − 125.25 = 109.85 ± 19.32
W 11.25 − 15.25 = 13 ± 1.60 11.00 − 15.50 = 13.50 ± 1.81 10 − 15.25 = 13.50 ± 2.05 13.25 − 30 = 23.95 ± 6.43 46.50 − 101.75 = 87.60 ± 23.57
13. Luffa acutangula var. amara C.B.Clarke L 15.25 − 45 = 29.85 ± 10.89 30.75 − 46 = 38.05 ± 6.45 23.25 − 82.81 = 41.61 ± 24.37 12.75 − 25.25 = 17 ± 5.54 76.25 − 125.25 = 109.90 ± 19.33
W 10.25 − 15.75 = 13.45 ± 2.25 13.00 − 22.75 = 17.95 ±3.97 12.75 − 20.75 = 16.40 ± 3.83± 10.25 − 22.75 = 15.80 ± 5.58 46.50 − 101.75 = 87.60 ± 23.57
14. Luffa cylindrica (L) M.Roem L 17.50 − 37.75 = 28.80 ± 7.97 21.25 − 31.25 = 26.50 ± 3.99 53 − 75.75 = 65.34 ± 9.45473 10.25 − 31.25 = 21.70 ± 9.30 101 − 139.25 = 119.90 ± 17.32
W 11.00 − 20.50 = 15.60 ± 3.76 11.25 − 17.50 = 13.80 ± 2.68 19.50 − 45.25 = 38.50 ± 10.88 7.50 − 27.75 = 17.55 ± 8 76 − 101.75 = 84.75 ± 10.84
15. Momordica charantia L. L 31.25 − 53.50 = 45.20 ± 9.05 21.25 − 26.25 = 24.45 ± 2.01 30.25 − 41.75 = 37.20 ± 4.36 22.25 − 31 = 26.85 ± 3.83 95.50 − 112.75 = 102.90 ± 7.33
W 11.25 − 28.50 = 19.35 ± 6.64 11.50 − 18 = 14.95 ± 2.63 11.25 − 19.50 = 15.05 ± 3.83 17.50 − 23.75 = 20.75 ± 2.89 71 − 77.25 = 73.70 ± 2.61
16 Momordica balsamina L. L 16.25 − 28.75 = 22.45 ± 4.88 16.25 − 21.25 = 19.60 ± 1.94 38.75 − 64 = 52.05 ± 9.07 7.25 − 11 = 9.50 ± 1.57 51.25 − 68.75 = 59.15 ± 7.87
W 13.75 − 20.50 = 16.70 ± 3.10 11.25 − 17.75 = 13.95 ± 2.58 31.25 − 48.75 = 39.95 ± 7.16 7.75 − 9.75 = 8.60 ± 0.741 41.25 − 50.50 = 45.90 ± 3.90
17 Praecitrullus fistulosus (Stocks) Pangalo L 20.00 − 47.50 = 32.70 ± 11.01 23.25 − 31.25 = 27 ± 3.08 62.50 − 126.75 = 91.55 ± 26 13 − 22.75 = 18 ± 4.09 138.25 − 153.75 = 147 ± 6.25
W 13.75 − 25.50 = 19.85 ± 4.97 12.25 − 17.75 = 14. ± 2.22 20 − 75 = 41.65 ± 27.69 10.25 − 18 = 14.35 ± 3 104.50 − 127.75 = 118 ± 11.78
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The UPGMA clustering dendrogram for Cucurbitaceous taxa is presented in Figure 10.

Figure 10.

Figure 10

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Cluster groupings via dendrogram of Cucurbitaceous taxa based on tendril features.

Seventeen taxa of Cucurbitaceae fall into two major clusters based on the difference in qualitative features. Similarity relationships among different Cucurbitaceous species were explored using UPGMA clustering using tendril anatomical characters. The UPGMA phenogram shows two main clusters, C1 and C2. The first principle cluster, C1, represents sections C. maxima and C. pepo. The second cluster C2 further divided into two sub-clusters comprising C2a1 of 5 species in which C. melo and C. balsamina were closely related based on Euclidean distance mapping. The second sub-cluster, C2a2, represents ten species, among which, based on Euclidean distance L. cylindrica and M. charantia was placed at the minimum distance in this sub-cluster, showing the similarity in tendril qualitative features.

Identification Keys Based on Cucurbitaceous Tendril Features

1 + Lamellar Collenchyma …………………………………………………...........................2  
− Angular Collenchyma…….……………………………………………………….............5
2 + Vascular bundle with round shape, irregular tendril outline…...…….............L. siceraria
- Lamellar and angular collenchyma………………….…………………………..…...……3
3 + Irregular vascular bundle, 6-angled tendril outline………………………………..C. pepo
- Oval and irregular vascular bundle………………..………………………………..……..4
4 + C shaped tendril shape…………………………………..……….C. pepo var. cylindrica
 - Angular collenchyma cell layers……..…………………………………...……………….5
5 + Tendril outline oval, vascular bundle slightly oval……..……………..……C. colocynthis
 - Subsidiary type vascular bundles………………………………………………………….6
6 + V shaped tendril, elliptical shape vascular bundle…………….………………...C. lanatus
- Irregular tendril outline…………...……………………………………………………….7
7 + Subsidiary type vascular bundle, rectangular epidermal cells……………………...C. melo
- Polygonal sclerenchyma cells……………………………….……………………………..8
8 + 4-angled tendril outline, irregular vascular bundle………………..C. melo subsp. agrestis
- Irregular tendril shape…………..………………………………………………................9
9 + Tetragonal sclerenchyma cells…………………….………………C. melo var. flexuosus  -
Triangular to polygonal sclerenchyma cells………..………………………………………10
10 + Central vascular bundle type..………......................................C. melo var. cantalupensis
- Elliptical and irregular vascular bundle shape…………………………………………...11
11 + Star shape tendril outline……………………………………………………….C. sativus
- Rectangular epidermal cells, irregular tendril…………………….……………………12
12 + Dumbbell type vascular bundle………………………………………………..C. maxima
- Rounded vascular bundle shape………………………..………………………………13
13 + Irregular with hollow pith tendril sape……………………..…………..…..L. acutangula
- Rounded to oval vascular bundle shape………….……………………………………14
14 + Polygonal tendril outline…………………………………...… L. acutangula var.amara
  - Hexagonal tendril outline.…………………………………………15
15 + Hexagonal to polygonal chlorenchyma cells………………………….……L. cylindrica
- 4-angled tendril, rectangular to polygonal chlorenchyma cells………………………16
16 + Central type vascular bundle, tetragonal sclerenchyma cells………………M. balsamina
- Pentagonal chlorenchyma cells…………………………………………………………17
17 + Rounded and elliptical vascular bundle type……………………………M. charantia
- Rectangular epidermal cells, subsidiary vascular bundle type…………………………18
18 + Polygonal slightly U shaped tendril outline………………………………….P. fistulosus
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Figure 1.

Figure 1

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(A) Field pictorial view of Citrullus colocynthis (L.) Schrad. (B) Tendril cross-section of Citrullus colocynthis (L.) Schrad. (Scale bar = 10 µm) (C) Field pictorial view of Citrullus lanatus (Thunb.) Matsum. & Nakai (D) Tendril cross section of Citrullus lanatus (Thunb.) Matsum.& Nakai (Scale bar = 10 µm).Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 2.

Figure 2

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(A) Field pictorial view of Cucumis melo L. (B) Tendril cross-section of Cucumis melo L. (Scale bar = 10 µm) (C) Field pictorial view of Cucumis melo subsp. agrestis (Naudin) Pangalo (D) Tendril cross-section of Cucumis melo subsp. agrestis (Naudin) Pangalo (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 3.

Figure 3

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(A) Field pictorial view of Cucumis melo var. flexuosus (L.) Naudin (B) Tendril cross-section of Cucumis melo var. flexuosus (L.) Naudin (Scale bar = 10 µm) (C) Field pictorial view of Cucumis melo var.cantalupensis Naudin (D) Tendril cross-section of Cucumis melo var.cantalupensis Naudin (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 4.

Figure 4

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(A) Field pictorial view of Cucumis sativus L. (B) Tendril cross-section of Cucumis sativus L. (Scale bar = 10 µm) (C) Field pictorial view of Cucurbita maxima Duchesne (D) Tendril cross-section of Cucurbita maxima Duchesne (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 5.

Figure 5

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(A) Field pictorial view of Cucurbita pepo L. (B) Tendril cross-section of Cucurbita pepo L. (Scale bar = 5 µm) (C) Field pictorial view of Cucurbita pepo var. cylindrica (D) Tendril cross-section of Cucurbita pepo var. cylindrica (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 6.

Figure 6

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(A) Field pictorial view of Lagenaria siceraria (Molina) Standl. (B) Tendril cross-section of Lagenaria siceraria (Molina) Standl. (Scale bar = 5 µm) (C) Field pictorial view of Luffa acutangula (L.) Roxb (D) Tendril cross-section of Luffa acutangula (L.) Roxb (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 7.

Figure 7

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(A) Field pictorial view of Luffa acutangula var. amara C.B.Clarke (B) Tendril cross-section of Luffa acutangula var. amara C.B.Clarke (Scale bar = 10 µm) (C) Field pictorial view of Luffa cylindrica(L.) M.Roem (D) Tendril cross-section of Luffa cylindrica(L.) M.Roem (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 8.

Figure 8

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(A) Field pictorial view of Momordica charantia L. (B) Tendril cross-section of Momordica charantia L. (Scale bar = 10 µm) (C) Field pictorial view of Momordica dioica Roxb. ex Willd. (D) Tendril cross section of Momordica balsamina L. (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

Figure 9.

Figure 9

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(A) Field pictorial view of Praecitrullus fistulosus (Stocks) Pangalo (B) Tendril cross section of Praecitrullus fistulosus (Stocks) Pangalo (Scale bar = 10 µm). Ad epi, Adaxial epidermis; Ab epi, Abaxial epidermis; Co, Collenchyma; Ch, Chlorenchyma; Sc, Sclerenchyma; Pa, Parenchyma; Vb, vascular bundle.

3. Discussion

Various studies described morpho-anatomical features to classify Cucurbitaceous species [13,14]. Different researchers have carried out the tendril anatomical investigation of a few species of Cucurbitaceae [20] and studied the anatomical characteristics of some species of the genus cucurbita, like flower stalk, petiole, and stem, and examined some tendril characteristics. Leaf anatomy of Cucurbitaceous species has been briefly mentioned by [21], but no information is available on the tendril anatomy of Cucurbitaceous taxa, so this study elaborates tendril histology of 12 Cucurbitaceous taxa to find out taxonomic markers for their correct identification. The tendril’s shape was four and five angled furrows in Momordica charantia and Cucumis sativa [22], which shows similarities with current results. While current studies show tendrils outlined in transverse view in different cucurbitaceous taxa are mostly irregular, slightly oval-shaped, slightly C shaped, angular (four-angled, six-angled, or polygonal), and star-shaped (Table 1). The maximum tendril length was observed in Cucurbita pepo (656.1 µm) and minimum was observed in Momordica balsamina (123.05 µm) as shown in Figure 11. Whereas the maximum width of tendril was noted in Cucurbita maxima (489.6 µm) and minimum in Momordica balsamina (112.95 µm).

Figure 11.

Figure 11

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Mean tendril size variations among Cucurbitaceous taxa.

There was a single-layered epidermis present in the tendril histological section and it was predominantly irregular in shape while oval-shaped cells were recorded [22]. However, [23] elaborates on rectangular cells whereas our findings show square, oval, isodiametric, irregular, pentagonal, hexagonal, and polygonal types. Significant variation in the tendril micromorphology of Cucurbitaceous taxa was observed on both the adaxial and abaxial epidermal sides. There was variation in the epidermal cell length and width of the studied species (Table 3). The largest cell lengthwise was noted on the adaxial side in Praecitrullus fistulosus (28 µm) and the smallest in Luffa cylindrica (13 µm). The maximum epidermal cell width was noted in Cucumis melo var.cantalupensis (18.2 µm) and minimum in Luffa acutangula (8.05 µm) as shown in Figure 12.

Figure 12.

Figure 12

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Graphical representation for epidermal cell size on the Adaxial surface of tendril.

Correspondingly, the largest cell length was calculated along the abaxial in Praecitrullus fistulosus (27.65 µm) and the shortest in Cucumis melo subsp. agrestis (12.85 µm). The cell width was observed to be maximum on the abaxial surface in Cucurbita pepo var. cylindrica (18 µm) and minimum in Luffa acutangula var. amara (4.1 µm). Layers of sclerenchyma and chlorenchyma (both one to eight layers) and collenchyma cells (two to six layers). However, [22] mentioned some variations in sclerenchyma two to nine, chlorenchyma one to three and collenchyma two to six as mentioned in Figure 13.

Figure 13.

Figure 13

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Graphical representation for epidermal cell size on the abaxial surface of the tendril.

Angular collenchyma cells were observed from Iraq by [23] among Cucurbitaceae species from Iraq, while angular lamellar types were examined in this study (Table 1). In previous studies, two to four layers of collenchyma were present [22], while present measurements revealed a distinct continuous layering of cells below the epidermis with two to six layers of collenchyma (Table 2). The maximum layers were present in Cucurbita maxima and Luffa acutangula var.amara both having six layers, while the minimum number of layers was present in Citrullus lanatus, with two or three layers. Collenchymatous cell size showing maximum length in in Cucumis sativus (27.85 µm) while minimum length was in Cucurbita pepo (12.85 µm). Whereas the largest width was calculated for Cucumis sativus (17.7 µm) the lowest width was for Cucumis melo var. flexuosus (8.55 µm) as illustrated in Figure 14.

Figure 14.

Figure 14

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Graphical Representation of collenchyma length and width on the surface of tendril.

There were mostly two or three layers of chlorenchyma in tendrils of Cucurbitaceae species [22], while in recent studies, a single layer of chlorenchyma cells lies beneath collenchyma but in some species, more than single layers noticed two or two to three layers (Table 2). Maximum chlorenchymateous layers were present in Lagenaria siceraria in two to three layers. Different shapes of chlorenchyma cells were inspected, such as rectangular, irregular, pentagonal, hexagonal, and polygonal (Table 1). The chlorenchymateous cell size range from largest lengthwise was measured in Cucumis sativus (44.25 µm) while the shortest was in Cucumis melo subsp. agrestis (20.6 µm). Likewise, the largest cell widthwise was seen in Cucumis melo var. cantalupensis (27.45 µm), and the smallest cell widthwise was observed in Cucumis melo subsp. agrestis (8.9 µm) Figure 15.

Figure 15.

Figure 15

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Graphical representation of chlorenchyma length and width on the surface of tendril.

Species like Citrullus colocynthis and Citrullus lanatus have continuous sclerenchyma cells, similar to our findings. All the studied species illustrated the continuous sclerenchymatous cells except Cucumis melo var catanlupensus, Cucurbita pepo var cylindrica, and Momordica charantia, discontinuous sclerenchymatous cells were recorded in these species. The continuous layer of sclerenchymatous cells that makes up the tendril acts as an anchor and requires it to be robust enough to hold the weight of the plant and its fruits, especially when it is rising [22]. The most prominent and darkly stained layers of sclernchyma cells were just below the chlorenchyma cell layers. Sclerenchyma cell layers range from a minimum of two to three layers in three species of Cucumis melo subsp. agrestis, Cucumis melo var. flexuosus, and Cucumis melo var. cantalupensis, while the maximum number of layers was noticed in Lagenaria siceraria seven to nine layers, Table 2. Shapes of sclerenchyma cells are dissimilar in tendrils of studied plant species. Mainly, sclerenchyma was perceived as irregular, trigonal, tetragonal, hexagonal, and polygonal shaped, Table 1. There were variations in sclerenchyma cell size ranges, maximum cell sizes lengthwise were seen in Luffa acutangula var. amara (38.05 µm) compared to minimum cell size lengthwise in Cucumis melo subsp. agrestis (13.55 µm). The maximum width of sclerenchyma cells was noted in Luffa acutangula var. amara (17.95 µm), while minimum was observed in Cucumis melo subsp. agrestis (9 µm) Figure 16.

Figure 16.

Figure 16

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Graphical representation of sclerenchyma length and width on the surface of the tendril.

In earlier studies, different parenchyma cells were irregular, pentagonal, and polygonal (Table 1), butt angular parenchyma cells were also recorded [23]. In the current studies, parenchymatous cells were present in all species, mostly occupying the pith region in tendrils. The number of parenchyma cell layers differed in all studied species in Table 2. The maximum parenchyma layers were present in Cucumis sativus six-layers, whereas the minimum was observed in Luffa acutangula var. amara of two-layers. Parenchyma cells were the largest cells in size present in tendrils. The largest cell lengthwise is Praecitrullus fistulosus (91.55 µm), while mini cells were present in Cucumis melo (29 µm). The sizeable cells, widthwise, are present in Citrullus colocynthis (63.35 µm), and compact cells widthwise were existingin Luffa acutangula (13.5 µm) Figure 17.

Figure 17.

Figure 17

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Graphical representation of parenchyma length and width on the surface of the tendril.

Vascular bundles were mainly arranged in a subsidiary manner, and few were centrally arranged in the case of Cucumis melo var. cantalupensis and Momordica charantia, Table 1. Bicollateral-types of vascular bundles were present in tendrils. Various writers have reported this feature in the Cucurbitaceae, which is constant across the analyzed taxa [3,4,14,24]. Their shapes vary from oval, elliptical, rounded, irregular, and dumbbell, Table 1. Each studied species has a different number of vascular bundles (Table 2). The maximum number of vascular bundles was detected in Luffa acutangula var. amara, having 12 vascular bundles, while the minimum number of vascular bundles was in Momordica balsamina, having three vascular bundles. Vascular bundles also vary in size. The largest vascular bundle lengthwise was present in Cucumis sativus (224.25 µm), while the smallest was observed in Cucurbita pepo var. cylindrica (26.1 µm). The largest vascular bundle widthwise was observed in Cucumis sativus (125.3 µm), and the smallest vascular bundle was present in Cucurbita pepo var. cylindrica (19.35 µm) Figure 18.

Figure 18.

Figure 18

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Graphical illustration showing vascular bundle size of tendril.

There was no record found about the vessel elements of the vascular bundle previously, while the current study showed a distinct number of vessel elements in the xylem of the studied species’ tendrils. Their numbers and size vary from species to species. The highest number of vessel elements were present in Cucumis sativus, of about 15, and the lowest number of vessel elements existed in Cucumis melo var. cantalupensis, at around four elements (Table 2). The biggest vessel element lengthwise was found in Cucumis sativus (42.55 µm), while the smallest vessel element lengthwise was present in Momordica balsamina (9.5 µm). The largest vessel element widthwise was observed in Cucumis melo var. cantalupensis (30.45 µm); meanwhile, the shortest was analyzed in Citrullus colocynthis (7.82 µm) Figure 19.

Figure 19.

Figure 19

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Graphical variations among tendril vessel elements.

No tendril anatomical data were found about Luffa aegyptiaca. However, the species was used against hydrocarbon-contaminated soil through rhizoremediation, and chemical analysis of this species was also carried out in research papers [25]. In Western Africa, three genera of the Cucurbitaceae family, e.g., Momordica, Luffa, and Trichosanthes, were studied for their foliar epidermis and tendril morphology. The significant differences in their leaf and tendril morphology provided additional data for classifying three genera in separate tribes [26]. Furthermore, many authors studied praecitrullus fistulosus for its medicinal, anthelmintic, and anticancer activities [27,28,29]. Among the tendril anatomical characters presented in the study, only a few discussed characters have been studied earlier for selected species [20,22,23], while other species investigated in the current project have not been investigated. A detailed review of the literature revealed that there is no comprehensive study regarding the tendril anatomical features of these plants.

4. Materials and Methods

4.1. Study Site and Selected Species of Family Cucurbitaceae

This research was conducted in the desert areas of districts of Bhakkar and Layyah in Punjab province. During March to July 2022, 17 Cucurbitaceous species each with 5 specimens were collected during field trips. Cucurbitaceous species sampling sites were georeferenced using a GPS device (German eTrex Venture) (Table 5).

Table 5.

Cucurbitaceous plant sampling along with localities, GPS coordinates, and herbarium vouchering.

S/N Species Name Locality GPS Coordinates Collection Date Voucher Number Accession Number
1. Citrullus colocynthis (L) Schrad. Patti Bulanda 31°15′24.67” N
71°25′28.66” E		 7 May 2022 QAU-NA-3 132045
2. Citrullus lanatus (Thunb.) Matsum.& Nakai Mian farm 31°17′46.31” N
71°24′41.17” E		 19 March 2022 QAU-NA-16 132053
3. Cucumis melo L. Mian farm 31°17′46.31” N
71°24′41.17” E		 19 March 2022 QAU-NA-15 132059
4. Cucumis melo subsp. agrestis (Naudin) Pangalo Rakhhonda lala 31°19′01.56” N
71°25′50.80” E		 7 May 2022 QAU-NA-7 132049
5. Cucumis melo var. flexuosus (L.) Naudin Patti Bulanda 31°15′24.67” N
71°25′28.66” E		 8 May 2022 QAU-NA-6 132047
6. Cucumis melo var.cantalupensis Naudin Rakhhonda lala 31°19′01.56” N
71°25′50.80” E		 7 May 2022 QAU-NA-9 132046
7. Cucumis sativus L. Mian farm 31°17′46.31” N
71°24′41.17” E		 19 March 2022 QAU-NA-14 132060
8. Cucurbita maxima Duchesne 47 TDA 31°31′46.92” N
71°09′56.33” E		 22 March 2022 QAU-NA-8 132052
9. Cucurbita pepo L. 47 TDA 31°31′46.92” N
71°09′56.33” E		 20 March 2022 QAU-NA-13 132056
10. Cucurbita pepo var. cylindrica Jahan khan 31°33′09.40” N
71°10′17.71” E		 20 March 2022 QAU-NA-11 132051
11. Lagenaria siceraria (Molina) Standl. Jahan khan 31°33′09.40” N
71°10′17.71” E		 20 March 2022 QAU-NA-17 132050
12. Luffa acutangula (L.)Roxb Basti Thind 31°15′31.94” N
71°27′20.64” E		 22 March 2022 QAU-NA-2 132055
13. Luffa acutangula var.amara C.B.Clarke Darkhana wala 31°16′13.57” N
71°25′03.28” E		 11 May 2022 QAU-NA-5 132044
14. Luffa cylindrica (L) M.Roem Basti Thind 31°15′31.94” N
71°27′20.64” E		 10 May 2022 QAU-NA-10 132054
15. Momordica charantia L. Jahan khan 31°33′09.40” N
71°10′17.71” E		 20 March 2022 QAU-NA-1 132057
16. Momordica balsamina L. 222 TDA 31°09′43.53” N
71°12′38.90” E		 14 July 2022 QAU-NA-18 132143
17. Praecitrullus fistulosus (Stocks) Pangalo Fateh pur 31°10′28.68” N
71°13′32.71” E		 10 May 2022 QAU-NA-4 132048
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The whole specimen was collected, including the tendrils, roots, stems, petioles, leaves, and flowers. Cucurbitaceous species were grown in cultivated field crops and wild places of the studied region. Plant specimens were pressed and dried in newspapers, identified and authenticated from the Herbarium of Pakistan (ISL). Cucurbitaceous species names were verified from the International Plant Name Index (www.ipni.org accessed on 9 October 2020) and Flora of Pakistan (www.eflora.org accessed on 9 October 2020). After preservation with ethanol and mercuric chloride solution the Cucurbitaceous herbarium specimens were deposited in the ISL herbarium.

4.2. Tendril Fixation

A solution of FAA (one part of 40% formaldehyde, 18 parts of 70% ethanol, and one part of glacial acetic acid) was used to fix mature tendrils for anatomical study for 12 h. They were moved for 2 h in 50% ethanol and then dipped into 70% ethanol for 2 h. Afterward, put in absolute ethanol at room temperature [22].

4.3. Histological Sectioning

Successive fixation of tendrils were sectioned using the standard technique outlined by [30] with several changes. Tendril sections were cleaned for about a minute, and any extra water was then removed by treating the sections with a series of alcohols ranging from 70% to 100%. The dehydrated pieces were then submerged in xylol for one hour to permeate the wax. At 60 °C, molten wax was used to preserve the tissues. Sections were transferred to cast using forceps and needles, and a cast was used for this. This wax-filled cast and its sections were chilled with cold water. The cast was afterward lifted out and processed for microtomes. A piece of around 15–20 µm was cut from half of the length from the base with the aid of a Shandon Microtome (Finesse 325). On a glass slide, these sections were moved, and egg albumen was scattered all over the slide. The slide was moved onto a hot plate and placed in an oven at 60 °C, where the wax expanded. The tissues were extracted from the wax using xylol for five minutes. Sections were washed thoroughly before being successively dehydrated with alcohol at concentrations of 100%, 90%, 80%, and 70%. For staining, fast green stain and Safranin O were applied. Slides were stained for 15 to 20 min before being cleaned with distilled water. Rehydration using a sequence of alcohol concentrations of 70%, 80%, 90%, and 100%, respectively was then performed. To make the slide better visible, xylol was employed. DPX mountant was placed on the slide for mounting, and the area received a cover slip. Each slide had a proper label and was dried [31].

4.4. Tendril Micromorphology

Slides were examined using a 40x-objective LM (OPTIKA Microscope, Italy). Digital cameras were used to capture photos of each sample under the 4, 10, and 40 objective lenses.

4.5. Light Microscopy

A reading sheet was used to record quantitative data. 10 to 15 readings of each species were taken under the Meiji (MT 4300H) LM at a magnification of 40×. For each species, minimum, maximum, mean and standard deviation values of various microanatomical parameters, including the length and width of the tendrils, the vascular bundles, collenchymatous cells, sclerenchyma cells, chlorenchyma cells and parenchyma cells, abaxial and adaxial epidermal cells, and the vessel elements, were calculated [32].

4.6. Statistical Analysis

The statistical SPSS 16.0 tool was used to analyze the corresponding average data for the measured values of tendril anatomical traits [33]. The effectiveness of the quantitative and qualitative features were evaluated using the UPGMA clustering analysis based on the Euclidean distance coefficient using PAST 4.03 software [34].

5. Conclusions

Through microscopic magnifications, the anatomical morphometry of tendril micromorphological features in Cucurbitaceous taxa exhibited variations. The resulting tendril micromorphology provides trustworthy traits that help identify different species. Accurate taxonomy will be achieved through the analysis of tendril characteristics. For taxonomic examination, it is crucial to consider the shape of the tendril outline, vascular bundle arrangements, sclerenchyma layers, and the morphology of the collenchyma and epidermal cells. The largest collenchyma cell was found in Cucumis sativus (27.85 µm), whereas the longest sclerenchyma cell was found in Luffa acutangula var. amara (38.05 µm). The findings show that the taxonomic identification of these species and their relationships will benefit from quantitative anatomical tendril features through clustering (UPGMA) analysis

Acknowledgments

The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code: 22UQU4430043DSR02.

Author Contributions

“Conceptualization, S.M.; methodology, S.S.; validation, M.Z., M.A. and T.M.; investigation, M.F.R.; resources, K.K.; data curation, T.B.; writing—original draft preparation, N.A.; writing—review and editing, S.M.; visualization, Y.G. and M.K.; supervision, M.Z. and M.A.; funding, A.T.A. All authors have read and agreed to the published version of the manuscript.

Informed Consent Statement

Not Applicable.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no potential conflict of interest regarding the publication of this research work.

Funding Statement

Deanship of Scientific Research, Umm Al-Qura University Grant Code: 22UQU4430043DSR02.

Footnotes

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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