Herbs, perennial, unarmed; from diffuse, woody, branched root system, sometimes stoloniferous. Stems erect, ± glandular, glabrate; unbranched or sparsely branched; proximal nodes often with cataphylls. Leaves alternate, odd-pinnate; stipules present, deciduous or persistent, reflexed, distinct; petiolate; leaflets 3, very rarely 4, petiolulate, blade margins entire, surfaces glabrous or pubescent. Inflorescences: 2 or 3 flowers per node (3–20 nodes), axillary, pseudoracemes; bracts present, deciduous. Pedicels present. Flowers papilionaceous; calyx tubular-campanulate (in bud), gibbous to campanulate (in fruit, concealing fruit), lobes 5, lobes equal to or less than tube; corolla cream or yellow, sometimes with purple blotch on wing blades and keel petals; banner bi-auriculate, wings auriculate, keel always shorter, apical margins connate; stamens 10, monadelphous early with vexillary stamen becoming distinct; anthers in 2 series, proximal ones dorsifixed, distal basifixed, introrse; receptacle tumid, style reflexed. Fruits legumes, sessile, elliptic or compressed-obovate, indehiscent, sometimes secondarily dehiscent by transverse rupture, apiculate or with beak ventrally displaced at maturity, eglandular or sparsely glandular, pubescent. Seeds 1, round to reniform, smooth.

Distribution

w North America, nw Mexico.

Discussion

Species 3 (3 in the flora).

Segregated by Grimes from Hoita in the sense of P. A. Rydberg (1919–1920) for the absence of a secondary internal wall in the fruit, Rupertia is distinguished from other genera of Psoraleeae by a combination of characters, including an accrescent calyx, cream to light yellow petals, deciduous bracts, and a tumid receptacle. Delimitation of Rupertia from Hoita is further validated by a molecular phylogenetic study of Psoraleeae (A. N. Egan and K. A. Crandall 2008).

Selected References

None.

Lower Taxa

Rupertia hallii, Rupertia physodes, Rupertia rigida

Key

1	Stipules 13–15 mm, widely elliptic to obtriangular; floral bracts 9–13 mm.	Rupertia hallii
1	Stipules 4–10 mm, linear-oblanceolate, linear-spatulate, triangular, or narrowly elliptic; floral bracts 3–7 mm.	> 2
2	Calyx in flower 6–8 mm; corolla banner 10–13.5 mm; legumes 4–7 mm, apiculate.	Rupertia physodes
2	Calyx in flower 9–10 mm; corolla banner 14–15 mm; legumes 9–13 mm, beaked (beak broadly attached).	Rupertia rigida