KEY TO FAMILIES OF EXOGEN WEEDS. 47 



ao. Stem leaves of our weeds either alternate or clustered at the ends of 

 the branches. 



c. Stem prostrate, succulent, spreading; leaves mostly clustered at 

 the ends of the branches; sepals 2; corolla regular, yellow. 



PURSLANE FAMILY, p. 76. 

 cc. Stem rarely prostrate, or if so not succulent and the sepals 



more than 2. 

 d. Ovary superior or wholly free from the calyx. 



e. Stamens numerous, at least more than 10; corolla regular. 

 /. Stamens all separate and distinct; ovaries simple, 1- 



celled. 



g. Sepals all separate and distinct; petals and stamens 

 borne on the receptacle at the base of the ovaries; 

 stipules none; our weeds with simple more or less 

 lobed leaves and yellow corollas. 



CROWFOOT FAMILY, p. 80. 



gg. Sepals more or less united at base ; petals and sta- 

 mens borne on the calyx ; stipules present ; our 

 weeds with compound, 3-5 foliate leaves and white 

 or yellow corollas. ROSE FAMILY, p. 85. 



//. Stamens all united in a column and connected at base 

 with the short claws of the petals (Fig. 11, 6.) ; 

 ovaries compound, several celled, often united in a 

 ring. MALLOW FAMILY, p. 95. 



ee. Stamens not more than 10. 



h. Petals 4; stamens 6, 4 long, 2 short, rarely only 2; 

 fruit a silique; herbs with a pungent watery juice. 



MUSTARD FAMILY, p. 81. 

 hh. Petals 5, the lower 2 often more or less united ; stamens 



never 6 or 2; fruit not a silique. 



i. Herbs; fruit a legume or pod; flowers mostly irreg- 

 ular and shaped like those of a pea (regular in 

 Cassia or wild senna ) . PEA FAMILY, p. 88. 



ii. Shrubs or woody vines; fruit a small drupe; flowers 

 regular; our included species with milky poisonous 

 sap. SUMAC FAMILY, p. 94. 



dd. Ovary inferior or partly or wholly united with the calyx. 

 j. Flowers not in umbels, yellow, nocturnal ; leaves simple ; 

 stamens in our weeds 8; ovules numerous in each cell 

 of the ovary. EVENING-PRIMROSE FAMILY, p. 99. 



jj. Flowers in umbels, white or yellow, diurnal ; leaves in our 

 weeds, compound; stamens 5; ovules 1 in each cell of 

 ovary. PARSLEY FAMILY, p. 100. 



KEY TO THE FAMILIES OF GAMOPETALOUS EXOGEN WEEDS. 



a. Ovary superior or wholly free from the calyx. 



6. Corolla not thin dry and colorless ; leaves not all basal ; flowers 



not in spikes on leafless flower stalks. 



c. Herbs with milky juice; leaves mostly opposite; fruit a follicle; 

 seeds bearing a long tuft of white hairs; ovaries 2, separate. 



