KEY FOR MARCH, APRIL AND MAY 



218 a Heads 2-4 in. broad; plant clothed with long hairs 



throughout; leaves usually entire. .Rudbeckia hirta. p 234. 

 b Plants not completely as in a 219 



219 a Outer flowers with the corolla 3-7 lobed or toothed 



at apex; lower leaves oblong or linear. .Coreopsis, p 235 

 b Plants not completely as in a Senecio. p 238 



220 a Flowers irregular 221 



b Flowers regular 227 



221 a Leaves compound; leaflets 6-10, with tendrils 



Lathyrus ochroleucus. p 174 



b Leaves not completely as in a 222 



222 a Flowers in a terminal spike or raceme 223 



b Flowers solitary on axillary stalks 225 



223 a Leaves entire Schwalbea. p 212 



b Leaves compound or lobed 224 



224 a Leaves pinnately parted or lobed Pedicularis. p 212 



b Leaves doubly compound; leaflets linear. .Capnoides. p 155 



225 a Leaves opposite, linear-lanceolate to ovate 



Melampyrum. p 212 

 b Leaves alternate, broadly ovate to heart-shaped .... 226 



226 a Plant very hairy; stipules ovate. ... Viola pubescent, p 188 

 b Plant not noticeably hairy; stipules lanceolate 



Viola scabriuscula. p 188 



227 a Perianth 6-parted, undifferentiated ; stamens 6 ; leaves 



entire 228 



b Plants not completely as in a 230 



228 a Flowers solitary on the flowering stalk ; leaves usually 



mottled Erythronium. p 135 



b Plants not completely as in a 229 



229 a Leaves basal; flowers in umbels Clintonia. p 135 



b Leaves not basal ; flowers solitary or 2 together 



Uvularia. p 133 



230 a Sepals 4; petals 4; stamens 6 231 



b Flowers not completely as in a 235 



231 a Basal leaves with terminal lobe only i or 2 times larger 



than the lateral lobes Roripa palustris. p 158 



b Basal leaves with terminal lobe several times larger 



than the lateral lobes 232 



232 a Flowers about % in. broad, showy and densely clustered 



at top of spike; leaves dark green, often shining 



above, not hairy Barbarea barbarea. p 158 



b Plants not completely as in a 233 



233 a Upper leaves with bases clasping the stem 



Brassica campestris. p 158 

 b Upper leaves not as in a 234 



234 a Flowers V in. or less broad Sisymbrium. p 757 



b Flowers %-% in. broad Brassica. p 158 



2 17 



