KEY FOR MARCH, APRIL AND MAY 



a At least the outer flowers of the head with strap-shaped 



corollas 253 



b None of the flowers of the head with strap-shaped 



corollas 256 



a Leaves pinnately divided into linear or lanceolate seg- 

 ments Anthemis arvensis. p 237 



b Leaves not completely as in a 254 



a Leaves basal Belli*, p 230 



b Leaves not all basal 255 



a Heads 1-2 in. broad; ray flowers white; leaves often 



pinnatifid Chrysanthemum, p 237 



b Plants not completely as in a Erigeron. p 233 



a Leaves with spiny-toothed margins Cnicus. p 240 



b Leaves not as in a 257 



a Leaves basal or wanting at flowering time ; flowers pink 

 to purple ; heads arranged in dense racemes 



Petasites. p 238 



b Plants not completely as in a 258 



a Leaves not white-woolly beneath; plant 1-4 ft. high 



Erigeron ramosus. p 233 



b Leaves white-woolly beneath 259 



a Bracts of involucre yellow Gifola. p 233 



b Bracts of involucre not yellow 260 



a No conspicuous basal \eaves.Gnaphalium purpureum. p 234. 



b Both basal and stem leaves present Antennaria. p 233 



a Flowers irregular 262 



b Flowers regular 291 



a Ovary inferior ; leaves entire 263 



b Ovary superior 265 



a Flowers with a large inflated lip i in. or more long, 



pink Cypripedium. p 138 



b Flowers not completely as in a 264 



a Leaves ovate, 2-5 in. long; flowers 3-6 together 



Galeorchis. p 138 

 b Leaves linear, 4-6 in. long; flowers usually solitary 



Arethusa. p 139 



a Flowers with the petals distinct 266 



b Flowers with the corolla or colored parts of the perianth 



tubular 274 



a Leaves compound . . 267 



b Leaves simple 271 



a Leaves palmately compound; leaflets 7-11. .Lupinus. p 174. 



b Leaves pinnately compound or with 3 leaflets 268 



a Leaves tendril-bearing at the ends 269 



b Leaves not tendril-bearing at the ends 270 



19 



