FliORA OF THE DISTRICT OF COLUMBIA. 3 7 



Calyx wholly united wilh the ovarj'^ and fruit; fruit iudehiscent; stamens 3; 



corolla nearly regular, white; pi ants annual,glabrou8.Valerianella (p. 261). 



Calyx free from the ovary and fruit; fruit a dehiscent capsule; stamens 2, 4, 



or 5; corolla usually irregular, variously colored; plants annual or 



perennial, usually pubescent SCROPHULARIACEAE (p. 248). 



Corolla of distinct petals,or sometimes wanting, the flowers sometimes small and green. 

 Leaves deeply lobed. 

 Plants glabrous; leaves only 2, borne at the top of the stem; flower 1, borne 

 between the leaves, wiih large white petals; fruit juicy. 



Podophyllum (p. 160). 



Plants pubescent; leaves more than 2; flowers usually more than 1; fruit dry. 



Petals present, the sepals green; fruit composed of 5 carpels; jjlants annual 



or perennial Geranium (p. 190) ; 



Petals none, but the sepals colored and petal-like; fruit of numerous achenes; 



plants perennial RANTJNCULACEAE (p. 156). 



Leaves only toothed, or rarely very shallowly lolled. 

 Plants with milky juice; fruit deeply 3-lobed. Corolla none, but the flowers 

 surrounded by an often corolla-like involucre. EUPHORBIACEAE (p. 194); 

 Plants with colorless juice; fruit not 3-lol)ed. 

 Flowers green, without petals; fruit 1-seeded. 

 Plants covered with whitish scales, never with slender hairs nor glabrous. 



flowers solitary or in spikes; stipules none Atriplex (p. 148). 



Plants glaljrous or with slender, sometimes stinging hairs; flowers mostly 



clustered; stipules present URTICACEAE (p. 142). 



Flowers wiih white or colored petals; fruit with more than one seed. 

 Petals large (1 cm. long or longer), pink or purplish; leaves .3-4-ribbed; 



plants bristly-htxiry MELASTOMATACEAE (p. 212). 



Petals small (much less than 1 cm. long); leaves not ribbed; plants not 

 bristly hairy. 

 Leaves about as broad as long; calyx free from the ovai-y and fruit; 

 petals white or yellow; i^lants flowering in spring; seeds never; 

 with a tuft of haira and fruit never bristly . SAXIFRAGACEAE (p. 171). 

 Leaves much longer than broad; calyx united with the ovary and fruit; 

 petals pink or whitish; plants flowering in summer or autumn; 

 seeds with a tuft of hairs or else the fi-uit covered with hooked bris- 

 tles ONAGR ACEAE ^p. 212) . 



Flowers sessile in dense heads on a common receptacle surrounded by an involucre 

 of bracts; corolla gamopetalous, regular or irregulai-; calyx represented by scales or 

 bristles or somodmes none; stamens united by their anthers in a ring; fruit an achene. 

 (These plan's are commonly called Composites. Tyjncal of them are the sunflower, 

 goldem-od, as'er, dandelion, and ragweed. The heads of flowers ai-e often mistaken 

 by amateur botanists for a single flower.) 



Plants with milky juice; corolla of all the flowers irregular, produced inio a strap- 

 shaped ray; leaves alternate or sometimes all basal... CICHORIACEAE (p. 263). 

 Plants not with milky juice; corollas all legular, or the outer ones jiroduced into a 

 strap-shaped ray; leaves alternate or opposite. 

 Flowers staminate and pistillate, the 2 kinds in separate unlike heads; involucre 

 of the pistillate heads woody, spiny; ray flowers none; flowers greenish or 



yellowish. (Ragweeds and cockleburs) AMBROSIACEAE (p. 267). 



Flowers all perfect, or both kinds in the same head, or rarely in separate heads, 

 but the heads then all similar in general appearance; involucre not woody 

 and spiny; ray flowers usually present ASTERACEAE (p. 268). 



