Pterospartum tridentatum (L.) Willk.
Genista tridentata L., Cytisus tridentatus (L.) Vuk., Genistella tridentata (L.) Samp., Chamaespartium tridentatum (L.) P.E.Gibbs.
Spa.: Carquesa, engordatoro.
Shrub or subshrub up to 0.5(2) m in height, unarmed, hermaphrodite, evergreen, highly ramose from the base, upright. Stems and old branches with brown-dark bark, smooth, that peels off revealing a second brown layer. Young branchlets with 5-6 ribs with an inverted V-shape, 2 ribs expanded into longitudinal wings, somewhat coriaceous and slightly ondulate, green. Leaves alternate, unifoliolate, sessile, with leaflets 3-7 mm, triangular and tightly joined to the stipules into a tridentate structure, coriaceous and recurved, that ends each winged internode. Inflorescence racemose, axillary or terminal, with 2-15 flowers shortly pedicellate —pedicel 1-5 mm, pubescent—, each accompanied by 2 bracteoles. Calyx 5-9 mm, campanulate, bilabiate, with lips shorter than the tube, the upper lip bipartite and the lower lip slightly larger, tridentate and with shorter teeth, yellowish-green, silky-villous. Corolla 9-15 mm, papilionoid, yellow, with an ovate standard, emarginate, glabrous or sericeous, wings and keel subequal in size to the standard. Androecium monadelphous, with 10 stamens. Ovary sericeous and stigma decurrent along the style. Pod 13-14 × 4-4.5 mm, ellipsoid, compressed, sericeous-villous, dehiscent, with 1-6 seeds visible externally. Seeds c. 3 mm, ovoid-suborbicular, compressed, smooth, dark brown.
Flowering:
March to July.
Fruiting:
July to August.
Habitat:
Forests and thickets in siliceous mountains, from sea level up to 2,000 m. In areas with subhumid to humid bioclimate, on mesomediterranean and supramediterranean floors.
Distribution:
Ibero-Mauritanian endemism. In North Africa it is restricted to Morocco, where it grows along the Rif and the Jebel Tazekka.
Observations:
A highly polymorphic species, of which various subspecies have been described, however not recognised by all authors. In North Africa 3 subspecies could be recognised, all confined to NW Morocco. One of them, P. tridentatum subsp. cantabricum (Spach) Talavera & P.E.Gibbs (Genista cantabrica Spach), groups the smaller plants (from 0.25-0.7 m) but which stems have larger wings (8-13 mm), and flowers with a glabrous standard or with a standard with only some scattered hairs along the midrib. In contrast, the other 2 subspecies have flowers with a villous-silky standard on the dorsal side, and some authors merge them into one taxon. One of them, P. tridentatum subsp. riphaeum (Pau & Font Quer) Talavera & P.E.Gibbs (Genistella riphaea Pau & Font Quer), which would endemic to the study area, would include larger plants (1-2 m in height), with subsessile flowers (pedicel <2 mm), and villous-silky standard. In contrast, P. tridentatum subsp. lasianthum (Spach) Talavera & P.E.Gibbs (Genista lasiantha Spach), would include somewhat smaller plants (0.2-1 m), with flowers with longer pedicels, 3-5 mm. The subsps. cantabricum and lasianthum also grow in the Iberian Peninsula.
Conservation status:
A relatively rare species but it does not appear to be threatened. In the IUCN Red List of Threatened Species it is listed as Least Concern (LC sub Genista tridentata) at global level (Groom, 2012).