Genus 19. 



PEA FAMILY, 



I. Petalostemum compactum (Spreng.) 

 Swezey. Dense-flowered Prairie- 

 clover. Fig. 2512. 



Dalea compacta Spreng. Syst. Veg. 3 ; ^^7' 1826. 

 Petalostemon macrostachyus Torr. Ann. Lye. 2: 176, 



1828. 

 P. compactus Swezey, Nebraska Flow. PI. 6. 1891. 

 Kuhnistera compacta Kuntze, Rev. Gen. PI. 192. 1891, 



Erect, dotted with sessile glands, branched, i°-2i° 

 high. Leaflets 5-7, glabrous,' short-stalked, oblong- 

 lanceolate or linear-oblong, acute or obtusish, dotted 

 beneath, 6"-i2" long, about 2" wide ; peduncles ter- 

 minal, elongated, not bracted ; spikes cylindric, 2'-6' 

 long, about 6" thick, the rachis pubescent ; flowers 

 white or nearly so, about 2" long; bracts awn- 

 pointed, longer than the densely villous-pubescent 

 calyx; wings and keel-petals oblong; standard cor- 

 date ; pod pubescent, enclosed by the calyx. 



In dry soil. South Dakota to Nebraska, Kansas, 

 Colorado and Wyoming. July-Aug. 



2. Petalostemum candidum (Willd.) 



Michx. White Prairie-clover. 



Fig. 2513. 



Dalea Candida Willd. Sp. PI. 3: 1337. 1803. 

 P. candidum Michx. Fl. Bor. Am. 2: 49. 1803. 

 Kuhnistera Candida Kuntze, Rev. Gen. PI. 192. 

 1891. 



Glabrous, stems erect, assurgent, or rarely 

 prostrate, simple, or sparingly branched, i°-2° 

 high. Leaves petioled; leaflets 5-9, oblong, or 

 oblanceolate, 8"-i2" long, i4"-3" wide, obtusish 

 or acute and often mucronulate at the apex, 

 narrowed at the base, very short-stalked ; pe- 

 duncles terminal, elongated, bracted ; spikes 

 cylindric, i'-4' long, s"-6" thick; bracts awn- 

 pointed, longer than the calyx; corolla white, 

 2"-3" long; wings and keel-petals oval;, stand- 

 ard cordate ; calyx-teeth and pod slightly pu- 

 bescent. 



Prairies and plains, Indiana to Minnesota, 

 Manitoba, Tennessee, Louisiana, Texas and Colo- 

 rado. June-Aug. White tassel-flower. 



3. Petalostemum oligophyllum Torr. 

 Slender White Prairie-clover. Fig. 2514. 



Petalostemon gracile van oligophyllum Torr. Em- 

 ory's Mil. Rec. 139. 1848. 



Kuhnistera Candida var. occidentalis Rydberg, Contr 

 Nat. Herb. 3: 154. 1895. 



Kuhnistera oligophylla Heller, Bull. Torr. Club 23: 

 122. 1896. 



Petalostemon oligophyllum Torr. ; Smyth, Trans. 

 Kans. Acad. 1$: 61. 1898. 



Glabrous, stem slender, erect or ascending, usu- 

 ally_ much branched, l°-2i° tall, the branches 

 straight, ascending. Leaves short-petioled; leaf- 

 lets about 7 (5-9), linear, linear-oblong or some- 

 what oblanceolate, firm, varying from less than 

 l" wide to 2" wide, mostly less than 10" long, 

 or those of the lower leaves larger; spikes oblong 

 or short-cylindric, blunt; bracts lanceolate, acu- 

 minate, equalling the calyx, or longer, deciduous ; 

 calyx-teeth usually pubescent; corolla white. 



Plains, South Dakota to 

 Texas, Arizona and Mexico. 

 1° long. June-Sept. 



Nebraska. Wyoming, 

 Root sometimes over 



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