KEY TO FAMILIES 



I. Petals present 



1. Flowers in heads, as in the aster and clover 



a. Ovary superior TRIFOLIUM IN 



FABACEAE 186 



b. Ovary inferior 



( 1) Petals separate ; style simple ; upper leaves 



in a whorl of 4-6 CORNACEAE 222 



(2) Petals united; style 2-cleft; leaves rarely 



whorled ASTERACEAE 243 



2. Flowers single or in clusters 

 a. Petals separate 



(1) Petals 1-3 



(a) Petal 1; stamens 10; shrub AMORPHA IN FABA- 



CEAE 170 



(b) Petals 2 



x. Ovary superior, smooth 



(x) Water plants ; stamens 2-3 ELATINACEAE 42 



(y) Land plants; stamen 1 CALYPTRIDIUM IN 



PORTULACACEAE 



49 



y. Ovary inferior, bristly-hairy CIRCAEA IN ONA- 



GRACEAE 201 



(c) Petals 3 



x. Sepals green, unlike the petals 



(x) Leaves grass-like; flower withering 



in a few hours COMMELINACEAE 



304 



(y) Leaves usually broad; flower per- 

 sistent 

 m. Pistils 6-many, distinct; water 



plants ALISMACEAE 299 



n. Pistil 1, compound, with 3 cells; 



land plants LILIACEAE 304 



y. Sepals and petals more or less alike in 



color 

 (x) Flowers regular 



