FLORA OF THE DISTRICT OF COLUMBIA. 29 



Leaves, at least most of them, deeply lobed or divided. 

 Blades of the leaves furnished with small bladders, finely dissected; fiowera 



yellow ■. PINGUICULACEAE (p. 255). 



Blades of the leaves without bladders; -flowers green or white. 



Flowers conspicuous, with white petals, solitary on long slender pedicels. 



Cabomba (p. 155). 

 Flowers minute, green, sessile or nearly so. 

 Flowers in spikes; blades of the upper leaves merely toothed or lobed; 



fruit nutlike, 4-lobed HALORAGIDACEAE (p. 214). 



Flowers not in spikes; blades of all the leaves dissected; fruit not 4-lobed. 

 Leaves less than 1 cm. long, soft; fruit 1-seeded. 



CERATOPHYLLACEAE (p. 155). 

 Leaves usually much more than 1 cm. long, rigid; fruit many-seeded. 



PODOSTEMACEAE (p. 171). 



Leaves compound, of 2 or more .leaflets. 



Plants without leafy stems, the leaves all at the base, the flowering stems naked. 

 Leaflets 2; fruit a capsule, opening by a lid. Juice colored; flowers white. 



Jeflfersonia (p. 160). 

 Leaflets 3 or more ; fruit not opening by a lid . 

 Flowers apparently solitary, each "flower" really consisting of a spike of small 

 flowers surrounded by a corolla-like spathe; fruit a berry. Leaflets acute. 



Arisaema (p. 113). 

 Flowers in racemes or umbels; fruit a capsule. 

 Leaflets 3, entire, notched at the apex; flowers in umbels, regular. 



lonoxalis (p. 191). 

 Leaflets more than 3, much divided into narrow lobes; flowers in racemes, very 



irregular BikukuUa (p. 163). 



Plants with leafy stems. 

 Corolla papilionaceous (shaped like that of a bean or pea); fruit a legume. Leaves 



alternate, with stipules FABACEAE (p. 181). 



Corolla not papilionaceous; fruit not a legume (except in Caesalpiniaceae). 

 Flowers borne in a dense head on a common receptacle surrounded by an involucre 

 of bracts (the head often taken to be a single flower). Fruit an achene; 

 stipules none; corolla gamopetalous. 

 Plants with milky juice; leaflets 3; corollas all irregular.. Prenanthes (p. 265). 

 Plants with colorless juice; leaflets usually more than 3; corollas regular, or the 

 outer ones irregular. 

 Pistillate and staminate flowers in separate heads, the involucres of the fertile 



heads hard and woody, spiny Ambrosia (p. 268). 



Pistillate and staminate flowers in the same head, or the flowers all perfect, 



the involucres never. hard or spiny ASTERACEAE (p. 268). 



Flowers not borne in a dense head on a common receptacle surrounded by an 

 involucre of bracts. 

 Stems bearing only a single leaf or a pair or whorl of leaves. 

 Sepals and petals each 4; fruit a long narrow dry pod. Leaflets 3 or 5. 



Dentaria (p. 169). 

 Sepals 5 or more; petals 5 or more or united or wanting; fruit juicy or of few 

 or many achenes in a head. 

 Fruit a head of achenes; corolla none, but the sepals petal-like. 



RANUNCULACEAE (p. 156). 



