PlantaeDB Logo
Login Sign-up

Genus Ononis 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!

The genus Ononis L. (restharrow) belongs to the Fabaceae family, subfamily Faboideae, tribe Trifolieae, with approximately 75 species distributed primarily across the Mediterranean basin and into Macaronesia (POWO, 2024; WFO, 2024). The type species is Ononis spinosa L., historically treated as a polymorphic complex. These are typically perennial herbs or small shrubs, often with spiny or winged stems, and a characteristic viscous or glandular indumentum producing an aromatic odor.

Diagnostic morphology includes trifoliolate leaves with dentate to entire leaflets, persistent stipules, and axillary inflorescences bearing papilionaceous flowers typical of Fabaceae. The calyx is five-lobed with teeth equal to or shorter than the tube, the standard petal is broadly obovate and often purple to pink, and the keel is straight to slightly curved. The unilocular ovary contains numerous ovules with marginal placentation, developing into elongated, dehiscent pods (tetrachenes) that split along both sutures.

Centers of diversity occur in the western Mediterranean, with high endemism in Iberian Peninsula and North African mountain systems. Species occupy diverse habitats from coastal dunes and limestone slopes to alpine meadows up to 2,500 meters elevation (Greuter et al., 1986). Major biogeographic patterns reflect Mediterranean sclerophyllous adaptation with several Macaronesian endemics.

Intrinsic biology shows adaptation to Mediterranean climates with summer drought tolerance. Seed dispersal mechanisms are poorly documented, though fruits split explosively when dry. Base chromosome number is x = 8, with extensive polyploidy documented (Siljak-Yakovlev et al., 2002).

Recent taxonomic revisions based on molecular phylogenetics (Lewis et al., 2005) have clarified relationships, though some sectional circumscriptions remain unstable. Traditional sections Natrix and Ononis broadly correlate with molecular clades, but synonymization of several species complexes continues. Alternative treatments recognizing multiple segregate genera have been proposed but lack broad acceptance.

Human relevance includes horticultural use of several ornamental species, particularly O. rotundifolia and O. natrix, though some taxa behave as agricultural weeds. Native Mediterranean species occasionally naturalize in horticultural settings but rarely become invasive.

Conservation outlook suggests mountain endemics face climate change threats, while ongoing taxonomic instability hinders effective conservation prioritization (ECB, 2021). Enhanced phylogenetic resolution and standardized conservation assessments remain research priorities.

Pick a Species to see its components: