44 



21a. Beak of pod 3 4 mm. long Black Mustard, Brassica nigra. 

 21b. Beak of pod 5 mm. long or more 



Indian Mustard, Brassica juncea. 



22a. Leaves dentate or lobed Charlock, Brassica arvensis. 



22b. Leaves deeply pinnatifid 23. 



23a. Pod dehiscent when ripe by two valves, tipped with a flat or 

 angled beak White Mustard, Brassica alba. 



23b. Pod indehiscent, with spongy cross-partitions between the seeds, 

 tipped with a conical beak 



Wild Radish, Raphanus raphanistmm. 



24a. Terminal segment of the principal leaves much larger than 

 the lateral segments; flowers in spring and summer 25. 



24b. Terminal, segment of the principal leaves equaling or 

 smaller than the lateral ones (5 10 dm. high; pods very long 

 and slender; flowers in summer) 



Sisymbrium, Sisynibrium altissimum. 



25a. Flowers about 3 mm. wide; pods erect and closely appressed to 

 the stem (3 9 dm. high; weed blooming in summer) (Hedge 

 Mustard) 26. 



25b. Flowers about 7 mm. wide; pods spreading or ascending (3 6 

 dm. high; flowers in spring) (Winter Cress) 27. 



26a. Pods pubescent Hedge Mustard, Sisymbrium officinale. 

 26b. Pods glabrous 



Hedge Mustard, Sisymbrium officinale var. leiocarpum. 



27a. Lateral leaf-segments 5 8 pairs on the principal leaves 



Winter Cress, Barbarea yerna. 

 27b. Lateral leaf-segments 1 4 pairs on the principal leaves 28. 



28a. Flowers bright yellow, in racemes; pods spreading or 

 ascending Winter Cress, Barbarea vulgaris. 



28b. Flowers pale yellow, in corymb-like clusters; pods erect and 

 somewhat appressed Winter Cress, Barbarea stricta. 



29a. Principal stem-leaves compound or deeply lobed (the upper- 

 most or bracteal leaves may be simple) 30. 



29b. Principal stem-leaves entire, dentate, serrate, or sometimes 

 shallowly lobed or none (the basal leaves, at the surface of 

 the ground, may be deeply lobed or compound) 42. 



30a. Leaves ternately divided or compound (2 5 dm. high; 



flowers in spring) (Toothwort) 31. 

 30b. Leaves pinnately divided or compound 33. 



31a. Leaf-segments lanceolate or narrowly oblong 



Toothwort, Dentaria laciniata. 



31b. Leaf-segments ovate or ovate-oblong 32. 



32a. Stem-leaves 2, opposite or nearly opposite 



Toothwort, Dentaria diphylla. 

 32b. Stem-leaves 2 5, alternate Toothwort Dentaria maxima. 



