FLORA OF THE DISTRICT OF COLUMBIA. 45 



Leaves shallowly but sharply several-lobed ; twigs smooth. 



PLATANACEAE (p. 173). 

 Flowers clustered, but not in dense globose heads; leaves ovate to elliptic; 

 not lobed (sometimes 3-lobed in Sassafras). 

 Twigs and leaves strongly aromatic; anthers opening by uplifting lids. 



LAURACEAE (p. 16]). 

 Twigs and leaves not aromatic; anthers not opening by lids. 



Leaves serrate (sometimes entire in Celtis), very oblique at base. 



ULMACEAE (p. 140). 

 Leaves entire. 

 Winter buds pubescent; calyx cup-shaped, scarcely toothed; a shrub. 



DAPHNACEAE (p. 211). 

 Winter buds glabrous; calyx deeply 5-toothed; atree..Nyssa (p. 220). 

 Plants herbaceous. 

 Ovary or its cells containing several or many ovules. 



Calyx none; plant a small aquatic PODOSTEMACEAE (p. 171). 



Calyx present; plants terrestrial or sometimes growing in water. 

 Ovary inferior. 

 Ovary 6-celled; stamens 6-12; plants terrestrial. 



ARISTOLOCHIACEAE (p. 143). 

 Ovary 1 or 4-celled; plants growing in water or on mud. 



Ovary 1-celled; stamens 8-10 Chrysosplenium (p. 171). 



Ovary 4-celled ; stamens 4 Ludwigia (p. 213). 



Ovary superior. 



Ovaries 2 or more, distinct RANTJNCULACEAE (p. 156). 



Ovary single. 



Leaves compound or deeply many-lobed . 



RANUNCULACEAE (p. 156). 

 Leaves simple. 

 Leaves alternate. Ovary 5-celled, 5-beaked. 



PENTKORACEAE (p. 171). 

 Leaves opposite or whorled . 



Capsule 3-celled; leaves whorled AIZOACEAE (p. 150). 



Capsule 1-celled; leaves opposite ALSINACEAE (p. 151). 



Ovary or its cells containing 1 or 2 ovules b, bb. 



B. PISTILS MORE THAN ONE, DISTINCT OR NEARLY SO. 



Calyx none. Flowers in nodding spikes; leaves cordate. .SATJRURACEAE (p. 132). 

 ■Calyx present. 



■ Stamens inserted on the calyx; stipules preseut Aphanes (p. 177). 



Stamens inserted on the receptacle; stipules none. . .RANUNCULACEAE (p. 156). 



BB. PISTILS SINGLE, SIMPLE OR COMPOUND. 



Ovary inferior or so closely invested by tlio calyx tube a« to appear so. 

 Plants aquatic, the submersed leaves finely divided. 



HALORAGIDACEAE (p. 214). 

 Plants terrestrial. 



Leaves opposite; flowers rose or purple, 3-5 in a broad thin involucre. 



ALLIONIACEAE (]). 149). 

 Leaves alternate ; flowers without an involucre . 



Leaves simple; flowers white, in panicles SANTALACEAE (p. 143). 



Leaves pinnate; flowers in spikes Sanguisorba (p. 177). 



