PlantaeDB Logo
Login Sign-up

Genus Psoralea in Subfamily Papilionoideae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Psoralea L. (Fabaceae) is a temperate–subtropical legume whose centre of diversity lies in the Cape Floristic Region of South Africa, with additional species in eastern and southern Africa; an early-treated element in North America, formerly included in P. pinnata var. cajonifolia and other names, is now excluded following modern re-circumscription (Eastwood et al., 2020; Deckert et al., 2002). The genus includes approximately 120 species (POWO, 2024; WFO, 2024). The type species is P. pinnata L., the name under which the genus was originally described (Deckert et al., 2002).

Diagnostic morphology centres on a glandular dotted leaf and flower syndrome: plants are shrubs or suffrutescent perennials with imparipinnate leaves that bear dark glandular punctae or pustules on their surfaces and margins; stipules are often persistent and may form a pair at the base of the petiole. Inflorescences are axillary racemes or panicles, and the flowers are resupinate via pedicel twisting. The corolla is papilionaceous with a keel that fuses near the apex, and the calyx is tubular to campanulate with five teeth that may enlarge into an inflated husk after flowering. The ovary is superior and typically contains a single ovule, leading to a single-seeded, indehiscent pod that often remains enclosed in the enlarged, papery to inflated calyx (Eastwood et al., 2020; Deckert et al., 2002).

The highest diversity is in the Cape, where many taxa are narrow endemics associated with fynbos and renosterveld vegetation; secondary centres occur in the Drakensberg and southern tropical Africa (Eastwood et al., 2020; WFO, 2024). Species occur from lowland coastal habitats to montane settings up to approximately 2000 m. Biogeographically, most lineages are limited to the winter-rainfall zone, with a subset extending into the summer-rainfall eastern seaboard (Eastwood et al., 2020).

Pollination and dispersal remain documented for only a few species, but short-tongued bees and other insects have been observed visiting flowers; dispersal is mainly by wind and gravity from the inflated calyces (Eastwood et al., 2020). The base chromosome number for Psoralea is x=10 (Mógó, 1976). Anatomically, the glandular indumentum and the persistent calyx that becomes a wing-like structure are distinctive.

Recent molecular phylogenetics supports the separation of Psoralea from previously conflated genera such as Otholobium and Rupertia, reinforcing P. pinnata as a well-supported, early-branching member of a predominantly Cape clade (Eastwood et al., 2020; Deckert et al., 2002; POWO, 2024). Alternative taxonomic treatments that merged these groups are no longer widely followed.

Human relevance is chiefly horticultural: several South African taxa are cultivated as ornamentals and used in restoration plantings for their pollinator value, while certain others are known for their ecological roles rather than direct utility (Eastwood et al., 2020; WFO, 2024).

Many Psoralea species are threatened by habitat fragmentation and habitat degradation; conservation prioritisation is impeded by unresolved taxonomy in some complexes and incomplete occurrence data. Continued phylogenomic work and refined species limits will be essential to guide management and protect endemics under future climate scenarios.

Pick a Species to see its components: