Venezuela. Mérida: Sierra Nevada, 3500 m, Jun 1847, Funck & Schlim 1546 (lectotype, designated by Simpson 1979, pg. 28: P!; isolectotypes: G!; phot at F!).

Trees 3–7(12) m tall. Leaves strongly congested at the branch tips, imparipinnate with 2–3(–4) pairs of lateral leaflets, obtrullate in outline, 3.9–4.2 × 2.5–3.8 cm; rachises glabrous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically acute with spurs, almost glabrous with some hairs at the edges on the outer surfaces and glabrous in the inner surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.8–2.1 × 0.8–1.0 cm; margin entire, coriaceous, apically emarginate to retuse, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely sericeous with whitish hairs 0.7–1.0 mm long. Inflorescences pendant, 3.3–4.5 cm long, bearing 9–15 flowers; floral bracts 4.1–6.4 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 4.2–8.1 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 13–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.9–2.5 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 4.0–7.4 × 3.4–9.6 mm including spines. Diploid.

Polylepissericea is found in two distinct geographic areas, the Cordillera de Mérida in the Andes of western Venezuela and the Cordillera Central of Colombia in Caldas, Quindio and Risaralda Departments (Fig. 41). It grows at 2800–4300 m elevation in humid montane forest, where it is the only species of the genus. In Venezuela, P.sericea mostly grows as homogeneous forest and sometimes mixed with Hesperomelesglabrata and H.pernettyoides (Arnal 1983). In Colombia, it represents 61.9% (1893.07 ha) of the total Polylepis forest estimated for this country (Fadiño and Caro 2009). In the Cordillera Central, it grows mixed with Myrsineparvifolia, Miconiasalicifolia and Gynoxysbaccharoides (Rangel-Ch and Arellano 2007). This species has been subject to detailed ecological and ecophysiological studies in Venezuela which, among other aspects, revealed that the net photosynthesis is highest at leaf temperatures of 13 °C, but is still 80% of this maximum at 3 °C and that it has high concentrations of carbohydrates in its leaves that allow supercooling down to -9 °C (Rada et al. 1985, 1996, 2009; Goldstein et al. 1994). Leaf anatomy changes with elevation to account for lower temperatures and increasing water stress at high elevations (Colmenares-Arteaga et al. 2005). As in many species of the genus, natural regeneration is highest along forest margins and in open forests, where shading is low enough to allow for seedling growth, but where herb cover is too low to outcompete them (Rada et al. 2011).

The estimated Extent of Occurrence (EOO) for Polylepissericea is 36,560 km². The Area of Occupancy (AOO) is 100 km². The species is known from 16 locations. It is protected in Venezuela within the Sierra Nevada and Sierra de la Culata National Parks, with some minor relicts in the highest areas of the Trujillo State, where more than 50% of the remnant forest of P.sericea are conserved (Arnal 1983). In Colombia, forest remnants of P.sericea are protected within Los Nevados National Park. We assess P.sericea as Vulnerable (B1a+B2a).

In her seminal taxonomic revision of the genus Polylepis, Simpson (1979) adopted a broad species concept of P.sericea, with the result that it was long considered the most widespread species of the genus. However, Boza Espinoza et al. (2019) subdivided the species into five morphologically, geographically and ecologically different species, namely P.albicans, P.argentea, P.canoi, P.ochreata and P.sericea. This treatment is also supported by the fact that, in Peru, two of these species (P.argentea and P.canoi) co-occur in mixed forests without interbreeding (Boyle 2001). Later, Boza Espinoza et al. (2020a) further separated P.humboldtii and P.loxensis from P.ochreata, resulting in the current recognition of seven species within what Simpson (1979) recognized as the single species P.sericea.

As defined by Boza Espinoza et al. (2019) and here, P.sericea can be distinguished from the most similar species P.ochreata by the number of leaflet pairs (2–3(–4) versus 4–7), leaflet margin (entire versus entire to slightly serrate), leaflet hair length (0.7–1.0 mm versus 0.3–0.5 mm), inflorescence length (3.3–4.5 cm versus 8.1–17.4 cm) and flower number (9–15 versus 21–49).

Colombia. Caldas: Pereira, El Cisne, Laguna del Otúm, 04°46'N, 075°25'W, 3900–4200 m, 20 March 2009, Vargas 20063 (COL!). Villamaría, Cordillera central, vertiente occidental; cabeceras del río Otún, Laguna del Mosquito y plan del Villar, 04°58'N, 075°21'W, 3650–3750 m, 26 November 1946, Cuatrecasas 23257 (COL!); Cordillera Central, vertiente occidental, vert. sudoeste del Ruiz, El Prisco, páramos, 04°58'N, 075°22'W, 3500–3600 m, 05 May 1940, Cuatrecasas 9327 (COL!). Quindío: Salento, Vereda Cocóra; below Nevado del Quindio, 3800 m, 20–22 May 1989, Luteyn 12974 (MO!). Risaralda: Pereira, Cordillera central, en el paso de la Laguna del Otúm hacia la Quebrada Africa, 04°47'N, 075°24'W, 4300 m, 09 February 1980, Jaramillo 6276 (COL!).

Venezuela. Lara: Morán, Páramo del Jabon (Vertiente Oriental), 09°34'N, 070°06'W, 3100–3400 m, 02 November 1969, Cuatrecasas 28216 (MERF); Páramo Jabón, camino al páramo Cendé, 09°34'N, 070°06'W, 3000–3200 m, 30 December 1999, Riina 1036 (VEN). Mérida: Caracciolo Parra Olmedo, Páramo La Culata en quebrada, 08°46'43"N, 071°03'04"W, 3581 m, 07 October 2006, Bonifacino 2541 (VEN). Justo Briceño, Páramos de Laguna Grande, 08°48'N, 070°56'W, 21 January 1929, Pittier 13253 (MO!, VEN). Libertador, Parque Nacional Sierra Nevada. Loma Redonda Teleferico station and south, 08°33'N, 071°05'W, 4068 m, 20 May 1988, Dorr 5220 (AAU!); Pico Bolivar, 08°33'N, 071°02'W, 4200 m, 17 January 1968, Walter 443 (GOET!). Miranda, carretera hacia Piñango, Páramo Piedras Blancas, Dtto. Rangel, 09°00'N, 070°50'W, 3700 m, 03 March 1982, Aymard 1050 (MO!); Dist. Justo Briceño. Páramo y chirivital en la vertiente NW del Alto del Totumo, hoya del Río Chirurí, a 19.5 km de El Aguila por la carretera a Piñango, 08°51'N, 070°49'W, 3900–4000 m, 02 April 1982, Berry 3812 (MO!); 3844 (MO!, VEN); de El Aguila a Piñango, 08°56'24"N, 070°50'47"W, 3820 m, 03 August 2010, Grande 2565 (VEN). Pueblo Llano, Andes de Merida/Steilhang oberhalb Laguna Negra, 08°56'N, 070°41'W, 3500–3700 m, 01 August 1958, Schwabe s.n (GOET!); Andes de Merida, 08°56'N, 070°41'W, 4000 m, 01 January 1973, Schwabe s.n (GOET!). Rangel, Margenes del Río Chama, cerca de Apartadevos, 08°47'N, 070°51'W, 01 July 1971, Aristeguieta 7886 (MO!); Quebrada de la Mucuchache, SE de la entrada, 3600 m, 16 June 1981, Briceño 298 (VEN); Dist. Rangel, cascada SE of Laguna de Mucubaji and below Pico Mucuñuque, Parque Nacional Sierra Nevada, 08°48'N, 070°49'W, 3600–3800 m, 15 June 1988, Dorr 5524 (MO!, VEN); Sierra Nevada, 08°36'N, 070°53'W, 3800 m, 20 July 1934, Farenholtz 1833 (GOET!); Sierra Nevada, 08°36'N, 070°53'W, 4000 m, 27 July 1934, Farenholtz 1927 (GOET!); Quebrada Yoyo, 08°43'N, 070°49'W, 3880 m, 12 April 1930, Gehriger 73 (MO!, VEN); Distr. Rangel. Sierra Nevada de Santo Domingo, road between Laguna de Mucubaji and Laguna Negra, 08°47'N, 070°48'W, 3400 m, 03 July 1979, Kieft 87 (MO!, VEN); moraine at the head of the valley above L. Mucubají, on a small rocky cliff just above and east of the lowest falls, 08°47'N, 070°49'W, 3650 m, 21 July 1972, Loveless 1722 (MO!); Sierra Nevada, 08°36'N, 070°53'W, s.d., Moritz 1120 (MO!); La Nevada, 08°36'N, 070°53'W, 3352 m, 21 December 1904, Schlim 1546 (MO!); Berghange oberhalb Laguna Negra/Páramo, 08°46'N, 070°48'W, 3700 m, s.d., Schwabe s.n (GOET!); Páramo de Mucubají, Páramo vegetation around Cascadas along the trail to Laguna Negra Páramo, 08°46'49"N, 070°49'16"W, 3640 m, 12 October 2007, Sklenar 10240 (VEN); Caserio Mifafi, camino quebrada de río Chama-Caserio Mucumpis a través del páramo Piedra Blanca (entrada por la carretera Apartaderous-Pico Aguila), 08°48'N, 070°50'W, 14 August 1980, Stergios 2116 (MO!); Páramo seco y húmedo en el sector de Sto. Domingo de Mucubají los alrededores de la Laguna de Mucubají, 08°46'N, 070°49'W, 29 May 1986, Stergios 8378 (MO!). Santos Marquina, Sierra Nevada. Páramo alrededores de la Laguna Verde proximo Picos Humboldt y Bonpland, near edge of la LagunaVerde, 08°34'N, 070°59'W, 4000 m, 04 December 1959, Barclay 10034 (MO!); Cerro de Caballo, 08°32'N, 070°54'W, 3600–3850 m, 25 November 1959, Barclay 9816 (MO!); Sierra Nevada; alrededores de la Laguna Coromoto. Trail to Laguna Verde, 08°34'N, 071°00'W, 3300–3500 m, 03 December 1959, Barclay 9951 (MO!), Parque Nacional Sierra Nevada, Mérida, Páramo Media Luna, 300 m Westl der Teleferico-Station Loma Redonda, 3920 m, 10 January 1995, Berg 517 (VEN); Páramo del Aguila, 10 March 1951, Croizat 66 (VEN); alrededores inmediatos de la Laguna Brava (Páramo de la Laguna Brava), sector del Páramo de los Granates, Sierra de Santo Domingo, Cordillera de los Andes, 3300 m, 20 May 1971, López-Figueiras 8728 (VEN); Páramo, Los Colorados, 3900 m, 01 May 1988, López del Pozo 416 (VEN); Páramo, 3550 m, July 1988, López del Pozo 944 (VEN); Parque Nacional Sierra Nevada, Laguna Negra, 17 September 1998, Ramirez 5533 (VEN); Laguna Mucubají, above Los Apartaderos, 3625–3655 m, 21 July 1944, Steyermark 57513 (VEN); Laguna Negra, 3520 m, 18 May 1952, Varechi 962 (VEN). Tachira: Jauregui, Páramo Sumusica along the trail heading northwest from the mountain pass (road La Grita-San Jose de Bolivar), 08°01'31"N, 071°57'53"W, 3340 m, 17 October 2007, Sklenar 10356 (VEN). Trujillo: Boconó, Mun. Carache, P.N. Dinira, arriba de Mesa Arriba, debajo del Pico Cendé, ladera SO, 09°32'N, 070°07'W, 3200 m, 01 April 1999, Duno de Stefano 767 (MO!, VEN).