Herbs, annual [perennial], or shrubs, armed or unarmed. Stems ascending, erect, procumbent, or decumbent, ± pubescent throughout [rarely glabrescent], hairs simple, glandular. Leaves alternate, odd-pinnate; stipules present, often leafy, adnate to petiole much of their lengths [rarely stipules fused]; petiolate; leaflets 1 or 3[or 5], blade margins usually serrulate, at least distally, rarely entire, surfaces pubescent; terminal blade larger than laterals. Inflorescences 1–3-flowered, terminal, leafy, racemes [spikes or panicles]; bracts present. Flowers papilionaceous; calyx campanulate or tubular, lobes 5, ± subequal; corolla usually pink or purple, sometimes white [variegated or yellow]; stamens 10, monadelphous (at least basally); anthers dimorphic, alter­nately basifixed and dorsifixed. Fruits legumes, tan to light brown, subsessile or stipitate, turgid, straight, ovoid or oblong-rhomboid [linear], usually not exceeding calyx, dehiscent, pubescent. Seeds 1–4[+], spherical or ovoid [reniform, suborbicular], smooth or tuberculate. x = 8.

Distribution

Introduced; Europe, Asia, n Africa, introduced also in Pacific Islands, Australia.

Discussion

Species ca. 80 (2 in the flora).

Ononis has been considered to be marginally related to Medicago, Melilotus, Trifolium, and Trigonella, which have been interpreted as constituting tribe Trifolieae, sometimes with the addition of Parochetus Buchanan-Hamilton ex D. Don (C. C. Heyn 1981). Ononis is often considered to constitute its own tribe, Ononideae Hutchinson. Molecular (plastid nucleic acid) phylogenetic analyses (M. F. Wojciechowski et al. 2000; K. P. Steele and Wojciechowski 2003; Wojciechowski 2003) have confirmed the close relationship of Medicago, Melilotus, and Trigonella, and also the rather distant relationship of Parochetus from the other genera. These analyses also indicate that Ononis is much closer to this group than hitherto appreciated, and that Trifolium is more closely related to genera of tribe Vicieae. This interpretation of generic relationships suggests that a redefinition of tribal composition is required, and that nomenclaturally the tribal name Trifolieae may need to be abandoned. Before such actions are taken, it is advisable to await additional studies of generic relationships.

Ononis is of limited economic significance, although some species are grown as ornamentals, some are weeds, and some are employed for medicinal purposes. Species of Ononis are sparsely introduced and rarely collected in the flora area.

Selected References

None.

Lower Taxa

Ononis alopecuroides, Ononis spinosa

Key

1	Shrubs (woody basally); stems with or without thorns; seeds tuberculate.	Ononis spinosa
1	Herbs; stems without thorns; seeds smooth.	Ononis alopecuroides