45 



33a. Plants growing in water, or in mud near water (spring and 



summer) 34. 

 33b. Plants of dry or moist soil 35. 



34a. Aerial leaves distinctly compound, with 3 11 leaflets 



Water Cress, Radicula nasturtium-aquaticum. 



34b. Aerial leaves merely serrate to pinnatifid; the submerged 



leaves, if present, dissected Lake Cress, Radicula aquatica, 



35a. Flowers 5 mm. broad, or less 36. 

 35b. Flowers 6 mm. broad, or more 39. 



36a. Stem-leaves irregularly pinnatifid or lobed; pod about as 

 broad as long (2 4 dm. high; flowers in summer) 



Garden Cress, Lepidium sativum. 



36b. Stem-leaves distinctly pinnatifid, with 3 6 pairs of lat- 

 eral segments (spring) (Bitter Cress) 37. 



37a. Leaves chiefly basal, pubescent on the upper side (1 3 dm. tall) 



Bitter Cress, Cardamine hirsnta. 



37b. Stem-leaves conspicuous, glabrous on the upper side 38. 



38a. Plant of dry soil; flowers about 3 mm. wide (1 4 dm. 



high) Bitter Cress, Cardamine parviflora. 



38b. Plant of moist or wet soil; flowers about 5 mm. wide 



(28 dm. high) Bitter Cress, Cardamine pennsyb anica 



39a. Leaves irregularly pinnatifid or lobed, not segmented into defi- 

 nitely paired divisions (coarse plants 4 8 dr^. high; flowers in 

 summer) 40. 



39b. Leaves deeply segmented into 3 10 pairs of divisions 41. 



4Ca. Flowers pink or white from the first 



Radish, Raphanus sativus. 

 40b. Flowers yellow at first, turning white with age 



Wild Radish, Raphanus raphanistrum. 



41a. Flowers pink or white, appearing in spring (2 5 dm. high) 



Cuckoo Flower, Cardamine pratensis. 



41b. Flowers yellowish or cream-color; a weed blooming in sum- 

 mer (510 dm. high) Sisymbrium, Sisymbrium altissimum. 



42a. A fleshy, much-branched plant of the shores of the Great 

 Lakes, with a pod transversely divided into two joints (2 3 

 dm. high; summer) Sea Rocket, Cakile edentula, 



42b. Pod not transversely divided into two joints 43. 



43a. Pod short, its length not more than 3 times its diameter 44. 

 43b. Pod long and slender, its length more than 3 times its diameter 



55. 

 44a. Pods not conspicuously flattened, thick and plump, about 



circular in cross-section (flowers in summer) 45. 

 44b. Pods distinctly flat 46. 



