486 FABA'CEAE 



united at the base. Corolla yellow or straw-colored; banner obovate, emar- 

 ginate, recurved; wings oblong, obtuse; keel incurved, very obtuse, shorter than 

 the wings. Stamens 10, diadelphic. Style filiform, barbate at the apex; stigma 

 terminal, barbate. Legume linear; flat, short-stipitate, few-seeded. Seeds 

 oval, compressed. 



Leaflets linear-elliptic or lanceolate, acute and mucronate, 2-6 mm long, or wanting; 



coroUa 12-15 mm. long. 1. P. scoparia. 



Leaflets broadly elliptic, oval, or obovate, rounded and mucronate at the apex, 8-15 



nun. long. 2. P. Thompsonae. 



1. P. scoparia A. Gray. Stem woody at the base, 5-10 dm. high, with 

 ascending branches; stipular spines slender, 3-5 mm. long; leaflets 9-15, linear- 

 eUiptic or lanceolate, acute at both ends, 2-6 mm. long, sparingly strigose; some 

 of the leaves reduced to merely the slender rachis; racemes 2-3 dm. long, lax; 

 calyx about 1 cm. long; teeth half as long as the tube; legume about 5 cm. long 

 or more, about 6 mm. wide. Valleys: w Tex. — sw Colo. — N.M. — Chihuahua. 

 Son. Je-Jl. 



2. P. Thompsonae S. Wats. Herbaceous, with rather simple stem, sparingly 

 strigose when young, 3-4 dm. high; leaflets 13-21, oval or obovate or broadly 

 elliptic, rounded at both ends, 8-15 mm. long, grayish strigose on both sides, 

 mucronate; raceme dense; pedicels and calyx glandular, as well as strigose; 

 calyx 10-15 mm. long, the lanceolate or subulate teeth equalling the tube; corolla 

 15-20 mm. long; legume about 5 cm. long and 4 mm. wide. Dry rocky clifTs: 

 Utah. Son. My-Jl. 



18. PHACA L. Rattle-weed, Rattle-pod. 

 Perennial or annual herbs, caulescent or rarely almost stemless. Leaves 

 alternate; stipules nearly free from the petioles, often partially united with each 

 other; leaflets many or few, entire, or in one species often cone. Flowers perfect, 

 racemose, or in one species subsessile in the axils of the leaves. Calyx campanu- 

 late. Corolla ochroleucous or purple; banner rather broad; wings longer than 

 the keel; the latter beakless. Stamens 10, diadelphous; anthers alike. Pod 

 membranous, inflated, sessile or stipitate, 1-ceUed, with neither suture intruded, 

 without even a partial partition. Seeds numerous. 



Upper suture of the pod not acute; pod circular or oval in cross-section. 

 Pod stipitate. 



Pod long-stipitate, not mottled ; stipe longer than the caly.x. 



Pod pendent; flowers oclu-oleucous. 1. P. americana. 



Pod on an ascending stipe; flowers purplish. 2. P. arnpularia. 



Pod short-stipitate; stipe scarcely exceeding the calyx. 

 Pod not mottled, erect or ascending. 

 Pod ashy-strigose, with minute hairs. 



Pods sulcata above; leaflets broad. 3. P. Wetherillii. 



Pod not sulcate; leaflets narrow. 4. P. allochroa. 



Pod glabrous. 



Flowers purplish; racemes long-peduncled ; pods about 2 cm. long. 



5. P. Eastwoodiae. 

 Flowers white; racemes short-peduncled ; pods 3-4 cm. long. 



6. P. lutosa. 

 Pod mottled, spreading or reflexed. 



Leaflets linear or none; plant grayish pubescent. 



Terminal leaflet none, represented by the much produced rachis; lateral 



leaflets often also lacking. 7. P. longifolia. 



Leaflets present; rachis not produced. 



Stem canescent, 1-2 dm. high; caly.x-teeth subulate. 



8. P. picta. 

 Stem glabrous or nearly so, 3-5 dm. high; calyx-teeth triangular. 



9. P. Cusickii. 

 Leaflets elliptic to broadly oval or obcordate. 



Plant glabrous. 10. P. artipes. 



Plant canescent. 11- P. Hookcriana. 



Pod sessile. 



Pod more than 12 mm. long. 



Plant densely cespitose, almost stemless; pod 3.5-5 cm. long. 



12. P. mcgacarpa. 

 Plant distinctly caulescent and leafy; pod 3 cm. long or lass. 



Whole plant glabrous. 13. P. Wardii. 



Plant, including the pods, pubescent. 



Calyx-teeth very short, scarcely one-third as long as the tube. 



14. P. subcinerea. 



