562 FABACEAE 



united. Standard large, reflexed; wings oblong, curved; keel obtuse, curved. Stamens 10, 

 diadelphous. Ovary stipitate ; ovules many. Pod flat, linear, not septate, tardily 2-valved. 

 [Name in honor of John and Vesparian Robin, who first grew the Locust-tree in Europe.] 



About 8 species, natives of North America. Type species, Robinia Pseudo-acacia L. 



1. Robinia Pseudo-Acacia L. Locust-tree. Fig. 2772. 



Robinia Pseudo-Acacia L. Sp. PI. 722. 1753. 



Tree with a rough bark, the twigs and foliage nearly glabrous. Stipules often spiny ; leaf- 

 lets 9-19, petiolulate, ovate to oval, entire, 25-50 mm. long ; racemes drooping, loosely-flowered ; 

 pedicels 6-12 mm. long ; flower white or slightly pinkish, fragrant, 15-20 mm. long, the standard 

 yellowish at base ; pod 5-10 cm. long, 12 mm. wide, glabrous. 



Native of eastern North America, and extensively cultivated. Spreading freely by underground parts and 

 becoming naturalized in the Pacific States from Washington to central California. May-June. 



16. OLNEYA A. Gray, Mem. Amer. Acad. II. 5: 328. 1855. 



Canescent spinose trees, with pinnate or odd-pinnate leaves, and obsolete stipules. 

 Racemes axillary. Calyx campanulate, 5-lobed, the two upper lobes united to near the 

 apex. Petals short-clawed, the blade of the standard rounded, reflexed with two callosities 

 at the base; wings obliquely obovate, strongly falcate; keel broadly lunate with a broad 

 basal auricle. Stamens 10, diadelphous. Ovary short-stipitate, several-ovuled. Pod rather 

 turgid, 2-valved, torulose. Seeds broadly ellipsoid, erect. [Name in honor of S. T. Olney, 

 1812-1878, New England botanist.] 



A monotypic genus of the arid southwestern United States and adjacent Mexico. 



1. Olneya Tesdta A. Gray. Desert Ironwood. Fig. 2773. 



Olneya Tesota A. Gray, Mem. Amer. Acad. II. 5: 328. 1855. 



Tree 5-8 m. high with a broad crown, and densely canescent branches. Spines 5-10 mm. 

 long, solitary or in pairs beneath the leaves, brown or black-tipped ; leaves 3-10 cm. long ; leaf- 

 lets 8-25, oblong to cuneate, 5-20 mm. long, canescent, rounded at the apex ; racemes 3-5 cm. 

 long ; bracts minute, deciduous ; calyx 3-4 mm. long, canescent, the lobes abruptly acute, scarcely 

 as long as the tube ; corolla yellow, 8-10 mm. long ; pod 4-6 cm. long, nearly 1 cm. wide, puberu- 

 lent and glandular-pubescent. 



Desert washes and valleys, Lower Sonoran Zone; Colorado Desert, California, to western Ariona, 

 Sonora, and Lower California. Type locality: tablelands on the Gila River, Arizona. May-June. 



17. SESBANIA Scop. Introd. 308. 1777. 



Herbs or shrubs, with abruptly pinnate leaves, the rachis ending in a setaceous point. 

 Stipules small, scarious, caducous ; leaflets numerous, linear-oblong. Flowers in axillary 

 racemes, bracteate. Calyx campanulate, the lobes shorter than the tube. Corolla yellow 

 or the standard purplish; standard with a suborbicular reflexed blade; wings with short 

 claws ; keel petals obtuse or rounded. Stamens diadelphous. Ovary short-stipitate, many- 

 ovuled. Pod linear, terete or slightly compressed, with septa between the seeds, 2-valved. 

 Seeds many, narrowly oblong. [Sesban, Arabic name of one of the species.] 



About 15 species, natives of the warm-temperate and tropical regions. Type species, Aeschynomene 

 Sesban L. 



1. Sesbania macrocarpa Muhl. Big-podded Sesbania, Bequilla. Fig. 2774. 



Sesbania macrocarpa Muhl. Cat. 65. 1813. 

 Darwinia exaltata Raf. Fl. Ludov. 106. 1817. 

 Sesban exaltatus Rydb. N. Amer. Fl. 24: 204. 1924. 

 Sesban sonorae Rydb. N. Amer. Fl. 24: 205. 1924. 



Annual, glabrous ; stems 3-10 dm. high, striate. Leaves 5-30 cm. long ; leaflets 20-70, linear- 

 oblong, 10—25 mm. long, rounded or oblong at each end, somewhat glaucous beneath ; racemes 

 2-6-flowered; bracts and bractlets narrowly linear; pedicels slender, 5-10 mm. long; calyx about 

 5 mm. long and as broad; lobes triangular-subulate, scarcely 2 mm. long; corolla about 15 mm. 

 long, yellowish, the standard streaked and dotted with purple; pod 10-15 cm. long, 3 mm. wide, 

 tipped with a slender beak, 15-30-seeded ; seeds 4 mm. long. 



River bottoms and canals, Lower Sonoran Zone; Imperial Valley and the lower Colorado River, Cali- 

 fornia, east to South Carolina and south to Central America. Type locality: South Carolina. March-Oct. 

 Colorado River Hemp. 



18. ASTRAGALUS [Tourn.] L. Sp. PI. 755. 1753. 



Annual or perennial herbs, sometimes woody at the base, with odd-pinnate leaves of 

 several to many leaflets and persistent stipules. Flowers purple, white or yellow, in axil- 

 lary spikes or racemes, rarely umbellate or solitary. Calyx 5-toothed. Petals with narrow 

 blade and slender claw ; keel obtuse. Stamens diadelphous. Stigma terminal, minute ; 

 ovary sessile or stipitate. Pod coriaceous and turgid, or thin and bladdery-inflated, 1- 



