KEY TO THE SPECIES 31 



2. Draba saxiniontana Aven Nelson (Rocky Mountain Dbaba). Peren- 

 nial, cespitose, the woody caudex of very numerous slender branches ; leaves 

 linear, short, densely crowded on the base of the stems ; the yellow petals about 

 twice as long as the elliptic sepals ; silique ovate, sub-acute, shorter than the pedi- 

 cel ; style short but evident. Frequent on stony ridges or sandy cliffs in the foot- 

 hills. 



11. CHEIRANTHUS (Wall Flower) 



Simple or branched herbs with roughish pubescence ; flowers rather large 

 with erect sepals, the petals with spreading blade ; silique loug-Iinear, 4-angled. 



1. Cheirantlius asper Nutt. (Western Wall Flower). Stem mostly sim- 

 ple, y-6 dm. high ; leaves oblanceolate, tapering into a petiole, entire or dentate ; 

 the upper narrower and sessile ; flowers large, about 15 mm. high and nearly as 

 broad ; silique 4-sided, 5-8 cm. long, widely spreading, Very common in early 

 spring on sandy slopes and plains. 



2. Cheiranthus Inconspicuus (Wats.) Greene. Freely branched above 

 and less pubescent ; the flowers smaller ; the silique slenderer, half as long and 

 nearly erect. Plains and shandy river banks. 



XXV. CAPPARIDACEiE (Caper Family) 



Herbs, with alternate leaves and perfect flowers, the sepals 

 and petals as in Cruciferoe, stamens 6 or more (not tetradyna- 

 mous), pod 1-celled with 2 parietal placental and reniform 

 seed.s. Rank-smelling weeds. 



1. Cleome. Pod long stipitate, drooping. 



2, Polanisia. Pod sessile or nearly so, erect. 



1. CLEOME (Cleome) 



Erect branching annuals, with leaves digitately 8-5-foliate ; conspicuous 

 flowers in bracteate racemes ; fruit long-stalked, elongated, with many seeds. 



. 1. Cleome serrulata Pursh (Pink Cleome. Rocky Mountain Bee-plant). 

 Glabrous and erect, tall and branching, often nearly 1 m. high ; leaves trifoliate ; 

 the leaflets lance-oblong, remotely serrulate, 4-8 cm. long ; bracts lanceolate- 

 linear ; the showy flowers pink (rarely white) ; fruiting raceme long ; pod com- 

 pressed, nearly linear, longer than the stipe, which about equals the pedicel. A 

 weed in waste grounds. A reputed honey plant. 



3. POLANISIA (Clammy Weed) 



Annual herbs resembling Cleome ; petals emarginate, clawed ; stamens 8-16, 

 exserted ; pod sessile. 



1. Polanisia trachysperma T. iS: G. Glandular-viscid, 2-4 dm. high ; 

 leaves trifohate ; the leaflets lanceolate ; flowers large, pinkish or yellowish ; 

 stamens exserted, with purple filaments ; pod lanceolate-linear, seeds usually 

 pitted or roughened. Sandy canons and bottom lands. 



