June, 1917] The BrassicacecB of Ohio 325 



10. Arabis brachycarpa (T. & G.) Britt. Purple Rock- 

 cress. Stems erect, simple or sparingly branched, 1-3 ft. high, 

 glabrous except at the base, glaucous and purplish; basal 

 leaves rosulate, densely stellate-pubescent, obovate, dentate, 

 petioled, 1-3 in. long; stem leaves glabrous, sagittate-lanceolate, 

 entire or few-toothed; flowers pink-purple or white; petals 

 twice the length of the calyx; pods linear, 1-3| in. long; seeds 

 winged, in 2 rows in each cavity. 



An indigenous biennial in sandy or rocky situations. Erie, 

 Ottawa. 



27. Cardamine (Tourn.) L. Bitter-cress. 

 Erect and ascending branching herbs, mostly glabrous, 

 with tuberous rootstocks or fibrous roots, simple or pinnately 

 divided leaves, and white or purplish flowers in racemes or 

 corymbs. Stamens 6 or 4. Siliques long, flat, elastically 

 dehiscent. Seeds flat, wingless, in 1 row in each cavity. 



1. Leaves simple, entire or coarsely dentate. 2. 



1. Leaves simple, pinnately divided. 4. 



2. Stems erect from a tuberous base; basal and stem-leaves different. 3. 



2. Stems decumbent; roots fibrous; basal and stem-leaves similar; flowers white, 



small. C. rotundifolia. 



3. Plant earh^, pubescent, purplish; flowers purple. C. douglassii. 



3. Plant later, glabrous, green; flowers white. C. bulbosa. 



4. Stems erect. 5. 



4. Stems weak; flowers white, very small. C. parviflora. 



5. Flowers white or purplish, showy. C. pratensis. 



5. Flowers white, small. 6. 



6. Stems mostly leafless; leaves rosulate, pubescent; stamens 4. C. hirsuta. 



6. Stems leafy; leaves glabrous. 7. 



7. Leaflets obovate or oblong; plant 8 in. to 3 ft. tall, branched. C. pennsylvanica. 

 7. Leaflets linear; plant 6 in. to 1 ft. tall, branched from the base. C. arenicola. 



1. Cardamine douglassii (Torr.) Britt. Purple Bitter- 

 cress. Stems clustered from a perennial tuberous rootstock, 

 usually simple, 4-15 in. high; basal leaves slender petioled, 

 ovate-orbicular, 1 in. broad, cordate, somewhat angular, 

 purple beneath; stem-leaves close, sessile, nearly dentate; 

 flowers in a lengthening raceme, corymbose at first, show}^; pod 

 1 in. long, pointed, erect. 



Indigenous in low, shady, moist places. General and 

 abundant. 



2. Cardamine bulbosa (Schreb.) B. S. P. Bulbous Bitter- 

 cress. Stems several from a slender tuberous rootstock, 

 6-20 in. high; basal leaves oblong or cordate-ovate, 1-1^ in. 

 long, on long petioles; stem-leaves scattered, lower petioled, 

 upper sessile, toothed or entire; pods as in C. douglassii. 



