FLORA OF THE DISTRICT OF COLUMBIA. 37 



Calyx wholly united with the ovary and fruit; fruit indehiecent; stamens 3; 



corolla nearly regular, white; plants annual, glabrous. 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 SCROPHTJLARIACEAE (p. 248). 



Corolla of distinct petals,or some) imeswanting. 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, with 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; plants annual 



or perennial Geranium (p. 190) ; 



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



plants perennial RANUNCTJLACEAE (p. 156). 



Leaves only toothed, or rarely very shallowly lobed. 

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

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

 Plants with colorless juice; fruit not 3-lobed. 

 Flowers green, without petals; fruit 1 -seeded. 

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



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



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



clustered ; stipules present URTICACEAE (p. 142). 



Flowers with 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-hairy MELASTOMATACEAE (p. 212). 



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

 bristly hairy. 

 Leaves about as tiro ad as long; calyx free from the ovary and fruit; 

 petals white or yellow; plants flowering in spring; seeds never; 

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

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

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

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

 tles ONAGRACEAE (p. 212), 



J. 



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

 of bracts; corolla garaopetalous, regular or irregular; calyx represented^ by scales or 

 bristles or sometimes none; stamens united by their anthers in a ring; fruit an achene, 

 ^These plan's are commonly called Composites. Typical of them are the sunflower, 

 goldenrod, a^:er, dandelion, and ragweed. The heads of flowers are often mistaken 

 by amateur botanists for a single flower. ) 



Plants with milky juice; corolla of all the flowers irregular, produced into 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 produced 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 alt 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). 



