Shrubs, 10–100[–160] cm, woody basally; rhizomes present or absent. Stems ascending, erect, or procumbent [prostrate]; thorns present or absent. Leaf­lets 1 or 3, blades ovate, elliptic, or oblong to narrowly oblong, 3–40 × 2–23 mm. Racemes dense or lax. Flowers 1 or 2 per node, pedicellate, (6–)10–20 mm; corolla usually pink or purple [white]. Fruits ovoid or oblong-rhomboid, 5–10 mm. Seeds 1–4, spherical to ovoid, 2–3 mm, tuberculate [smooth].

Distribution

Introduced; Eurasia, n Africa.

Discussion

Subspecies ca. 4 (3 in the flora).

R. B. Ivimey-Cook (1968) stated that, with regard to Ononis spinosa, a pair of chromosomes possess a long constriction such that it may appear to be two pairs, which probably accounts for the records of 2n = 32 (for subsp. spinosa) and for records of 2n = 32 and 64 (for subsp. maritima).

The taxonomy of what is treated here as Ononis spinosa in the broad sense is controversial and unsettled, with the three subspecies recognized here alternatively delimited as separate species (circumscribed as done here, more broadly, or more narrowly). Moreover, additional taxa have been recognized in Eurasia and circumscribed differently by various authors. The present treatment of all of the North American perennial Ononis as subspecies of O. spinosa is consistent with the circumscriptions and rankings in ILDIS (International Legume Database & Information Service), but use of the name O. spinosa subsp. maritima follows J. A. Davesa (2000).

Selected References

None.

Lower Taxa

Ononis spinosa subsp. hircina, Ononis spinosa subsp. maritima, Ononis spinosa subsp. spinosa

Key

1	Flowers borne in pairs at nodes; thorns absent.	Ononis spinosa subsp. hircina
1	Flowers usually borne singly at nodes; thorns present or absent.	> 2
2	Stems ascending or erect; thorns present; rhizomes absent.	Ononis spinosa subsp. spinosa
2	Stems procumbent or ascending; thorns often absent (when present, usually relatively soft); rhizomes often present.	Ononis spinosa subsp. maritima