Arquita Gagnon, G.P. Lewis & C.E. Hughes, Taxon 64(3): 479. 2015.

Fig. 49

Type.

Arquita mimosifolia (Griseb.) Gagnon, G.P. Lewis & C.E. Hughes [≡ Caesalpinia mimosifolia Griseb.]

Description.

Small to medium-sized, often decumbent, shrubs, usually with glandular trichomes on various parts of the plant. Stipules ovate-obovate to deltoid, usually with a fimbriate-glandular margin, caducous. Leaves bipinnate; pinnae 1-5 pairs, usually with a single terminal pinna; leaflets in 4-12 opposite pairs per pinna, often with maroon/black glands in depressions on crenulated leaflet margins, and sometimes with occasional sessile black glands on the undersurface of leaflet blades. Inflorescence a leaf-opposed raceme. Flowers bisexual, zygomorphic; hypanthium persistent as a small shallow cup at the pedicel apex as the fruit matures; sepals 5, caducous, the lower sepal cucullate; petals 5, free, yellow to orange, median petal sometimes streaked red; stamens 10, free; ovary usually covered with gland-tipped trichomes. Fruits laterally compressed, lunate-falcate legumes, covered sparsely to densely with gland-tipped trichomes, these sometimes dendritic. Seeds laterally compressed, ovate-orbicular, the testa shiny olive-grey, sometimes mottled or streaked black.

Chromosome number.

2 n = 24 ( A. mimosifolia) (Cangiano and Bernardello 2005).

Included species and geographic distribution.

Six taxa in five species restricted to the Andes in South America, in disjunct inter-Andean valleys, in Ecuador, Peru, Bolivia and Argentina (Fig. 49).

Ecology.

Tropical and subtropical seasonally dry, montane, and rupestral habitats.

Etymology.

Arquita is the vernacular name for A. trichocarpa (Griseb.) Gagnon, G.P. Lewis & C.E. Hughes in Argentina (Ulibarri 1996).

Human uses.

Unknown.

Notes.

A revision of Arquita with a key to species is available in Gagnon et al. (2015).

Taxonomic references.

Burkart (1936); Gagnon et al. (2015, 2016); Lewis (1998); Lewis et al. (2010); Ulibarri (1996).