Part 1, 1919] FABACEAE: PSORALEAE 5 



twice as long as the free claws; keel-petals shorter than the wings, usually with a dark tip, 

 the blades united at the rounded apex, similar to those of the wings but the basal lobe less prom- 

 inent, each slightly united with the adjacent wing at the base, the claws free. Filaments of 

 nine of the stamens united into a split or sometimes closed tube, 9-toothed at the apex, the teeth 

 short, alternately longer and shorter, the anthers of the shorter teeth sometimes smaller; 

 tenth stamen free except at the base, or united to the tube high up, or wanting. Style curved, 

 rarely abruptly bent towards the apex; stigma capitate. Pod ovate or orbicular, not included 

 in the calyx, somewhat flattened, indehiscent, with an incurved short beak; pericarp thick, 

 wrinkled, not coherent to the seed. Seed from suborbicular to reniform. 

 Type species, Psoralea latifoha Torr. 



Pod obliquely ovate; leaflets ovate to lanceolate; perennials with rootstocks. 



EuORBEXILUM. 



Stem erect, wholly herbaceous. 



Stipules and bracts subulate or lanceolate, the latter shorter than the 

 flowers. 

 Leaflets cuneate at the base; corollas 6-7 ram. long. 1. 0. Onobrychis. 



Leaflets cordate or truncate at the base; corollas 8-9 mm. long. 2. O. macro phyllum. 



Stipules and bracts ovate or obovate, the latter longer than the flowers. 3. O. stipulatum. 

 Stem spreading or trailing, woody at the base. 4. O. melanocarpum. 



Pod suborbicular; leaflets linear or linear-lanceolate; perennials with fusiform 



roots. POIKADENIA. 



Leaves 1-foliolate. 5. 0. virgalitm. 

 Leaves 3-foliolate. 



Bracts lanceolate; corolla 7 mm. long. 6. 0. simplex. 

 Bracts broadly ovate, acuminate; corolla 4—6 mm. long. 



Upper 4 calyx-lobes lanceolate, longer than the tube. 7. 0. pedunculatum. 



Upper 4 calyx-lobes triangular, shorter than the tube. 8. 0. gracile. 



1. Orbexilum Onobrychis (Nutt.) Rydberg. 



Psoralea Onobrychis Nutt. Gen. 2: 104. 1818. 

 Psoralea latifolia Torr. Ann. Lye. N. Y. 2: 176. 1827. 

 Lolodes Onobrychis Kuntze, Rev. Gen. 194. 1891. 



A perennial, with a stoloniferous rootstock; stem erect, 1-1.5 m. high, more or less finely 

 pubescent, angled and striate; leaves 3-foliolate; stipules 8-10 mm. long, subulate or setaceous; 

 petioles 4-8 cm. long; leaflets 5-10 cm. long, 2.5-6 cm. wide, rhombic-ovate or rhombic-lanceo- 

 late, acuminate, ciliate on the margins, glabrous and minutely glandular-punctate above, 

 more or less pubescent beneath, especially on the veins; peduncles 6-12 cm. long; racemes about 

 1 cm. long; bracts subulate, 3 mm. long; calyx 3 mm. long, glabrate; lobes triangular, shorter 

 than the tube; corolla 6-7 mm. long, pale with purple-tipped keel; banner suborbicular; blades 

 of the wings with an acute basal lobe, those of the keel-petals broader, two-thirds as long, with 

 a rounded lobe; pod obliquely ovate, flat, strongly transversely rugose-reticulate, and sometimes 

 tubercled, with an incurved beak, nearly 1 cm. long; seeds elliptic, 6 mm. long, red-brown, 

 smooth. 



Type locality: Banks of the Merrimek. a few miles from St. Louis. 



Distribution: Ohio to Illinois. Missouri, and Tennessee. 



Illustrations: Bot. Reg. 6: pi. 453; Britt. & Brown 111. Fl. /. 2100; ed. 2. /. 2503. 



2. Orbexilum macrophyllum (Rowlee) Rydberg. 



Psoralea macrophylla Rowlee; Small, Fl. SE. U. S. 623. 1903. 



A perennial; stem erect, 5-10 dm. high, angled, striate, retrorsely pubescent; leaves 3- 

 foliolate; stipules subulate or setaceous, fully 1 cm. long; petioles 3-8 cm. long; leaflets 6-10 cm. 

 long, 4-6 cm. wide, broadly ovate, blunt at the apex, subcordate at the base, finely pubescent 

 on both sides, finely reticulate beneath; peduncles 10-15 cm. long; racemes lax, about 1 cm. 

 long; rachis densely pubescent and with stalked glands; bracts lanceolate; pedicels 2-3 mm. 

 long; calyx densely pubescent and glandular; tube 2 mm. long; lobes lanceolate, the upper 

 2.5 mm., the lowest 3 mm. long; corolla 8-9 mm. long, purple; banner orbicular; blades of the 

 wings and the keel-petals broadly lunate, obtuse, those of the latter a little shorter. 



Type locality: Tryon Mountain, North Carolina. 

 Distribution: Known only from the type locality. 



