Colombia. Cundinamarca: Cordillera Oriental, Páramos de Bogota, Muzo, May 1844, Goudot s.n (holotype: P!).

Trees 2–10 m tall. Leaves slightly congested at the branch tips, imparipinnate with 3–4 pairs of lateral leaflets, obtrullate in outline, (4.2–)4.4–5.3(–6.5) × 2.4–3.2 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.5–2.0 × 0.7–1.1 cm; margin entire or slightly crenate with 4–6 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.7–0.9 mm long. Inflorescences pendant, (6.0–)7.3–10.5(–12.3) cm long, bearing 11–19 flowers; floral bracts 4.3–4.7 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers 6.8–9.5 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 9–19, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 3.7–4.6 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 4.6–6.5(–7.2) × 5.1–7.2 mm including spines. Diploid.

Polylepisquadrijuga is found in north-eastern Colombia from Páramo de la Rusia (Santander) across Páramo Guina, Páramo Belen, Páramo Guantiva and Sierra Nevada Cocuy (Boyacá) to Maciso de Sumapáz and Chingaza National Natural Park (Cundinamarca) (Fig. 61). It grows in humid Páramos at 2200–4250 m elevation. Polylepisquadrijuga represents 33.7% (1032.2 ha) of the total area of Polylepis forest identified for Colombia (Fadiño and Caro 2009). It is often associated with Diplostephiumtenuifolium (Asteraceae) and Escalloniamyrtilloides (Escalloniaceae) (Rangel-Ch and Arellano 2010).

The estimated EOO for Polylepisquadrijuga is 16,286 km² and the AOO is 84 km². It is known from 16 locations. Polylepisquadrijuga is protected within Chingaza and Sumapaz National Natural Parks and Cocuy National Park. Although the species occurs within these protected areas, it is also found in heavily fragmented forest regions. Perhaps the most worrying area is the corridor Rusia-Guantiva Páramos because of the absence of protected areas that would help to mitigate the current pressures (Rangel-Ch and Arellano 2007). The rising of the potato crop line is a strong threat to the permanence of these forests (Rangel-Ch and Arellano 2010), as is the reduction of the potential range due to climate change (Caballero-Villalobos et al. 2021). We assess P.quadrijuga as Vulnerable (A2a, B1a+B2a, D2a).

Polylepisquadrijuga resembles P.frontinensis. It differs from it by its elliptic leaflets with tomentose hairs 0.7–0.9 mm long, whereas P.frontinensis has obovate leaflets with villous hairs 1.4–1.8 mm long. Further, P.quadrijuga is morphologically similar to P.occidentalis, with which it shares elliptic leaflets, with deeply emarginate apices, entire to slightly crenate margins and densely tomentose lower leaflet surfaces. However, P.quadrijuga has broader leaflets 0.7–1.1 cm, longer lower leaflet surface hairs 0.7–0.9 mm, longer inflorescences 6.0–12.3 cm, bearing 11–19 flowers and longer styles 3.7–4.6 mm, whereas P.occidentalis has leaflets 0.5–0.8 cm width, lower leaflet hairs 0.3–0.6 mm long, inflorescences 2.4–6.7 cm long with 4–12 flowers and styles 1.5–2.0 mm long.

Colombia. Boyacá: Duitama, Corregimiento El Carmen, vía a Virolin, Páramo de La Rusia, 3400–3500 m, 19 November 1994, Betancur 5610 (COL!); Páramo de Rusia. Km 3 from the summit of the road Duitama-Abendaños, 3500 m, 12 February 1999, Stancík 2384 (COL!). El Cocuy, Cordillera Oriental, Sierra Nevada del Cocuy, Quebrada de San Paulino próximo Alto Ritacuva, 3500 m, 07 April 1959, Barclay 7303 (COL!, MO!); Cocuy National Park, Concavito Valley, 06°25'39"N, 072°19'15"W, 4000 m, 07 February 2017, Olivares 570 (Z!). Guicán, Guican. Alto de la Cueva limite Cocuy-Guican, Finca Eudoro Carreño y Margarita Carreño, estación del Himat, 06°24'33"N, 072°22'40"W, 3930 m, 14 October 1996, Cruz 164 (COL!). Susacon, 20 km passing Sussacon in direction to soata, 3150 m, 23 February 1999, Stancík 2463 (COL!). Cordillera Oriwntal; Páramo de Guina-Santa Rosita, 3300–3400 m, 03 August 1940, Cuatrecasas 10374 (US!); NNW de Duitama, Páramo de La Rusia, Avenida de Peñas Negras (Buenos Aires), 3550 m, 11 September 1989, Cuatrecasas 27741 (COL!); Hoya del Río Cusiana, Vadohondo, 2880 m, 31 March 1973, Cuatrecasas 28708 (COL!); Mpio. de Guican, vereda La Guaca, El Junco, 3716 m, 23 July 1981, López s.n (COL!); arriba de la confluencia con el río Upía, Río Olarte, 3015 m, 27 February 1955, Molano s.n (COL!); Páramo de Colorado, 3200 m, 11 May 1960, Montenegro 2717A (COL!). Cundinamarca: Pasca, Vereda Cajita, borde de Laguna Cajitas en el Páramo de Chisacá, 3700 m, 04 October 1983, Sarmiento 2000 (COL!). Santafé de Bogotá, Macizo de Sumapáz; Cuchilla La Rabona, 04°04'40"N, 074°13'00"W, 3900–3950 m, 17 July 1981, Díaz 2902B (COL!, MO!); Bogotá, D.C. Páramo de Sumapaz. ladera de la laguna Tunjos (Chisacá), 04°16'36"N, 074°12'17"W, 3725 m, 19 February 1997, Franco 5632 (COL!, MO!). Subachoque, Vereda Tobal, 2800 m, 09 November 2003, Hernández 1407 (COL!); carretera Cogua-San Cayetano, cebeceras Río Guandoque, 3 km al SW de la Laguna Verde, 3400 m, 01 June 1972, Cleef 4213 (COL!); Macizo de Bogotá, eastern slopes of Páramo de Chisaca. Quebrada de Santa Rosa, subPáramo, 3300–3350 m, 16 September 1961, Cuatrecasas 25999 (COL!); Dist. Especial de Bogotá; cordillera Oriental; lagunas de Chisacá; 40 km al N de Sumapaz, 3300–4000 m, 10 September 1959, García 17192 (AAU!); Fomeque, Páramo de Chingaza, a orillas de La Laguna, 3200 m, 03 November 1966, Huertas 6565 (COL!); Mpio. Bogota, Páramo de Sumapaz, entre la Laguna de Chisaca y Santa Rosa, 01 May 1989, Mahecha 10121 (COL!); Usme, al sur de Bogotá, 01 January 1944, Ranghel s.n (COL!); Macizo de Sumapaz, cerca a Santa Rosa, 3600–3700 m, 30 September 1963, Uribe 4491 (COL!). Santander: Encino, Vereda Rionegro, Microcuenca de la quebrada Chontales, 05°59'N, 073°04'W, 3400–3500 m, 15 December 1999, Galindo 300 (COL!).