164 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Upper stem leaves petioled or sessile, never clasping. 

 Leaves entire or toothed, never pinnately lobed or divided. 

 Plants with naked stems, the leaves in a basal rosette. Petals white; pods 



oval or oblong, about twice as long as wide, flat 1. DRAB A. 



Plants with leafy stems. 

 Leaves'glabrous. Plants perennial; petals white. 

 Upper leaves petioled; plants with the odor of garlic. Pods long and 



slender 11- ALLIARIA. 



Upper leaves sessile; plants not with the odor of garlic. 

 Basal leaves mucn longer than broad, mostly 20-30 cm. long or larger, 

 conspicuously toothed; pods less than twice as long as thick. 



7. ARMORACIA. 

 Basal leaves mostly as broad as long, rarely over 5 cm. long, usually 

 entire; pods much more than twice as long as thick. 



19. CARDAMINE. 

 Leaves, at least the lower ones, conspicuously haby. 

 Petals pink or purple, about 2 cm. long; pods long and slender, swollen 



over the seeds. Leaves conspicuously toothed 15. HESPERIS. 



Petals white or yellow, not mom than 0.5 cm. long; pods not swollen over 

 the seeds. 

 Petals yellov,-; pods long and tilcuder, not flattened; leaves entire or 



nearly so 12. CHEIRINIA . 



Petals white; pods about as broad a^ long, or long, slender, and flat. 

 Pods obovoid, nearly as broad as long; leaves all linear or nearly so, 



entire 2. KONIGA. 



Pods long and slender, flat; leaves, at least most of them, broader than 



linear, often toothed. 



Plants annual, with a conspicuous basal rosette of leaves; leaves 



mostly entire; pods less than 2 cm. long. ..16. ARABIDOPSIS. 



Plants perennial or annual, usually without basal rosettes of leaves; 



leaves all or nearlv all toothed; pods over 3 cm. long. 



18. ARABIS. 

 Leaves, at least some of them, pinnately lobed or divided. 

 Plants with conspicuously dimorphous leaves, growing in water, the submerged 

 leaves dissected into threadlike segments. Petals white; pods short and 



thick, less than twice as long as thick 8. NEOBECEIA, 



Plants not with dimorphous leaves, none of the leaves dissected into threadlike 

 segments. 

 Upper stem leaves linear or nearly so, most of them entire. Petals white. 

 Pods as broad as long, shorter than the pedicels; plants annual; petals less 



than 2 mm. long, sometimes wanting 9. LEPIDIUM. . 



Pods several times longer than broad, much longer than the pedicels; petals 



5-7 mm. long 18. ARABIS. 



Upper stem leaves broader than linear, toothed or pinnately lobed or divided . 

 Petals white or purple. 



Pods less than twice as long as thick; basal leaves simple. Plants with 



thick fleshy roots; petals white 7. ARMORACIA. 



Pods several times as long as thick; basal or lower leaves pinnately 

 divided. 

 Upper leaves simple; pods not splitting when ripe; petals mostly 



purple 23. RAPHANUS. 



Upper leaves pinnately divided; pods splitting when ripe; petals 

 white. 

 Pods flat, straight; leaflets of the upper leaves more than twice as 

 long as broad; plants not floating in water.. .19. CARDAMINE. 



