PEA FAMILY 517 



36. OROPHACA (T. & G.) Britton. 



Cespitose, silvery or villous perennials, with branched woody caudices and 

 deep roots. Leaves crowded, digitately 3-foliolate (rarely 5-foliolate\ with 

 scarious sheathing stipules. Flowers few, capitate or racemose. Calyx cam- 

 panulate to cylindric. Corolla yellowish or purplish. Keel blunt. Pod cori- 

 aceous, l-celle"d, without partition, ovoid or elliptic, few-seeded, villous or puberu- 

 lent, partly included in the calyx. 



Flowers sessile in the axils of the leaves, 12 mm. or more long; corolla ochroleucous ; 

 calyx-tube longei than the teeth; plant pulvinate-cespitose. 

 Corolla 2 cm. or more long, glabrous; calyx-tube cylindrical, more than thrice as 



long as the teeth. 1. O. caespitosa. 



Corolla 15-18 mm. long, piibescent on the outside; calyx-tube short-cylindric, about 

 twice as long as the teeth. 2. O. argophylla. 



Flowers in small, neduncled l-.3-flowered racemes, purple or turning yellowish in age, 

 less than 10 mm. long; calyx-tube campanulate, not longer than the tube-teeth. 

 Plant pulvinate-cespitose; flowers 8-10 mm. long; inflorescence not exceeding the 

 leaves. 

 Flowers about 10 mm. long; pods puberulent. 3. O. tridactylica. 



Flowers about 8 mm. long; pods hoary. 4. O. aretioides. 



Plant broadly cespitose, with prostrate branches; flowers about 6 ram. long; ped- 

 uncles asually exceeding the leaves; pods hoary. 5. O. sericea. 



1. O. caespitosa (Nutt.) Britton. Stems 5 cm. or less, densely covered 

 with leaves and scarious stipules; leaflets elliptic to narrowly oblanceolate, 0.5-2 

 cm. long, appressed silvery-silky on both sides; calyx silky; tube cylindric, 10-15 

 mm. long; teeth 3-4 mm. long; corolla 2-3 cm. long; legume oblong-ovate, terete, 

 silky-villous. Phaca caespitosa Nutt. Astragalus triphyllus Pursh. Dry gravelly 

 hills: Sask.— Neb.— Wyo.— Mont. Plain. My-Je. 



2. O. argophylla (Nutt.) Rydb. Stems less than 5 cm. high, densely covered 

 with scarious, ovate stipules; leaflets elliptic or obovate to oblanceolate, 5-15 

 mm. long, 3-5 mm. wide, appressed white-silky on both sides; calyx white silky- 

 villous; tube cylindric, 6-8 mm. long; teeth subulate, 3 mm. long; corolla 15-18 

 mm. long; legume short and rounded-ovate, densely villous. Phaca argophylla 

 Nutt. Astragalus hyalinus M. E. Jones. Dry hills and bad lands: w Neb. — 

 Wyo.— Colo. Plain. Jl-Au. 



3. O. tridactylica (A. Gray) Rydb. Stems less than 5 cm. high, densely 

 covered with leaves and scarious, pubescent stipules; leaflets broadly or narrowly 

 oblanceolate, 0.5-2 cm. long, 3-4 mm. wide, densely silky on both sides; calyx 

 silky; tube 3 mm. long; teeth 4 mm. long, subulate; corolla about 1 cm. long; 

 legimie globose-ovoid, 6-8 mm. long. A. tridactylicus A. Gray. Hills and 

 plains: Colo. Submont. My-Je. 



4. O. aretioides (M. E. Jones) Rydb. Stems more elongate than in the 

 preceding; leaflets broadly oblanceolate, 0.5-1 cm. long, 3-4 mm. wide; calj'x 

 densely silky; tube about 2 mm. long; teeth subulate, 2 mm. long; corolla 7-8 

 mm. long; legume ovoid. A. sericoleucus aretioides M. E. Jones. Dry hills: 

 Wyo. — Colo. Sub?7iont. My-Je. 



5. O. sericea (Nutt.) Britton. Branches of the caudex often. 1-2 dm. long; 

 annual branches 2-4 cm. long, densely covered with leaves and ovate scarious 

 pubescent stipules; leaflets oblanceolate to cuneate-obovate, 5-8 mm. long, 2-3 

 mm. wide, densely white-silky; calyx densely silky; tube 1.5 mm. long; teeth 

 about 1.5 mm. long; corolla purple, 6-7 mm. long; legumes ovoid. Phaca sericea 

 Nutt. A. sericokucus A. Gray. Dry hills: Neb. — Wyo. — Colo. Plain — 

 Submont. 



37. ARAGALLUS Necker. Loco-weed. 



Perennial herbs, mostly acaulescent. Leaves alternate, odd-pinnate. Flow- 

 ers racemose or spicate Calyx campanulate, its teeth almost equal. Petals 

 clawed; banner erect, ovate or oblong; wings oblong; keel produced at the apex 

 into a porrect point. Stamens 10, diadelphous; anthers all alike. Pods sessile 

 or stipitate, coriaceous, often more or less 2-celled by the intrusion of the upper 

 suture. [Oxylropis DC] 



