GENUS 29. 



PEA FAMILY. 



337 



29. KENTROPHYTA Nutt. ; T. & G. Fl. N. A. i : 353. 1838. 



Low tufted perennial pubescent herbs, with pinnately 3~7-foliolate leaves, the linear per- 

 sistent leaflets firm in texture, spinulose-tipped. Flowers 2 to 4 together in the axils or soli- 

 tary, nearly sessile, yellow or yellowish. Calyx campanulate, the teeth nearly equal. Keel 

 obtuse, shorter than the wings. Ovary few-ovuled. Pod short, ovate, i-celled, somewhat 

 coriaceous, with i or 2 seeds. [Greek, referring to the sharp-tipped leaflets.] 



About 5 species, natives of central North America, the following typical. 



i. Kentrophyta montana Nutt. Prickly Milk Vetch. Fig. 2558. 



Ketitrophyta montana Nutt. ; T. & G. Fl. N. A. i : 353. 1838. 

 Kentrophyta viridis Nutt. ; T. & G. Fl. N. A. i : 353. 1838. 

 Astragalus Kentrophyta A. Gray, Proc. Acad. Phil. 1863 : 



60. 1863. 

 Homalobus montanus Britton, in Britt. & Brown, 111. Fl. 2 : 



306. 1897. 



Densely tufted, intricately branched, 2'-io' high, finely 

 canescent. Stipules linear-lanceolate, spiny-tipped, 2"-$" 

 long; leaflets 3-7, linear, rigid, spiny, widely spreading, 

 3 "-6" long, i" wide; flowers 1-4 together in the axils, 

 nearly sessile, yellowish-white or bluish-tinged, 2"-$" 

 long; pod sessile or very short-stalked, i-3-seeded, 

 ovoid-oblong, acute, coriaceous, dehiscent, pubescent, 

 3"-4" long. 



In dry, rocky places, South Dakota to Nebraska, New 

 Mexico and Saskatchewan. June-Sept. 



30. OROPHACA Britton, in Britton & Brown, 111. Fl. 2 : 306. 1897. 



Perennial, silvery or villous-pubescent low tufted herbs, with branched woody caudices, 

 deep roots, membranous scarious stipules, sheathing and united below, and digitately 3-folio- 

 late (rarely s-foliolate) leaves, resembling those of Lupines. Flowers few, capitate or race- 

 mose, the clusters sessile or peduncled. Keel of the corolla blunt. Pod coriaceous, completely 

 i-celled, ovoid or oval, few-seeded, villous, partly or wholly enclosed by the calyx. [Greek, 

 mountain vetch.] 



Three known species, the following, and one in Colorado and Wyoming. Type species : Oro- 

 phaca cacspitosa (Nutt.) Britton. 



Flowers yellowish, 1-3 together in the axils. 



Corolla glabrous outside. i. O. caespitosa. 



Corolla pubescent outside. 2. O. argophylla. 



Flowers blue-purple, in peduncled racemes. 3. O. sericea. 



i. Orophaca caespitosa (Nutt.) Britton. Sessile-flowered Milk Vetch. 



Fig- 2559- 



1814. Not 



Astragalus triphyllus Pursh, Fl. Am. Sept. 740. 



Pall. 1800. 

 Phaca caespitosa Nutt. Gen. 2: 98. 1818, 

 Orophaca caespitosa Britton, in Britt. & Brown, 111. Fl. 2 : 



306. 1897. 



Silvery-canescent, densely tufted from a deep root, 

 2'-4' high. Stipules scarious, imbricated, glabrous, ovate- 

 lanceolate, 3"-4" long ; leaves digitately 3-5 -f oliolate, 

 slender-petioled ; leaflets oblong or oblanceolate, acute 

 or obtusish at the apex, narrowed or cuneate at the base, 

 6"-8" long; flowers yellowish, 6"-8" long, sessile in the 

 axils of the leaves ; calyx-teeth half as long as the tube ; 

 corolla glabrous ; pod i-celled, sessile, ovoid, acute or 

 acuminate, coriaceous, dehiscent, villous-pubescent, en- 

 closed by the calyx, 2"-^" long. 



Plains and hills, Kansas, Nebraska and South Dakota to 

 Montana and Saskatchewan. May-July. 



