36 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



B. SEPALS UNITED, AT LEAST BELOW, OFTEN NEARLY TO THE APEX. 



Flowers surrounded by a calyx-like involucre, the calyx pink, corolla- like. 



ALLIONIACEAE (p. 149). 

 Flowers not surrounded by an involucre; calyx green. 

 Flowers sessile in the forks of the branches, small, green. Leaves linear; plants 



annual Scleranthus (p. 151). 



Flowers not sossile in the forks of the branches, usually large and colored. 

 Petals inserted on the throat of the calyx; flowers axillary or whorled. 



LYTHBACEAE (p. 211). 

 Petals not inserted on the calyx; flowers mostly in cymes or panicles. 



SILENACEAE (p. 153). 



BB. SEPALS DISTINCT. 



Loaves whorled; flowers axillary, pcdiceled. Plant9 annual. AIZOACEAE (p. 150). 

 Leaves not whorled; flowers usually not axillary. 

 Flowers (calyx and bracts) greenish white, crowded in short slender spikes arranged 

 in loose panicles; petals none. Leaves broadly ovate, petioled . .Iresine (p. 149). 

 Flowers not as above; petals usually present, but sometimes falling early. 



Sepals 2; s;eni leaves a single pair. Petals pink Claytonia (p. 150). 



Sepals 5; stem leaves numerous. 

 Petals whi e or wanting; sepals equal or nearly so; stems usually soft and succu- 

 lent ALSINACEAE (p. 151). 



Petals yellow, greenish, or purpiish; nopals unequal, the 2 outer much narrower 

 than the 3 inner ones; stems rigid and almost woody. 



CISTACEAE (p. 205). 

 I. 



Plants with leafy stems; leaves opposite, the blades toothed or lobed, simple, net- 

 veined. 



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

 bracts. 

 Chaff of the receptacle (among the flowers) with long rigid spinelike tips; receptacle 

 several times as long as broad; stamens distinct. Leaves with prickly teeth. 



DIPSACACEAE (p. 2G2). 



Chaff of the receptacle not with long rigid spinelike tips, sometimes wanting; 



receptacle usually less than twice as long as broad; stamens united by their 



anthers in a ling Group J (p. 37). 



Flowers not sessile in dense heads on a common receptacle surrounded by an involucre 

 of bracts. 

 Corolla gamopetalous (of united pelals), usually colored and conspicuous. 



Fruit composed of 2 or 4 nutlets in the bottom of the calyx, these sometimes 

 united at first but separating in age. Stems usually 4-sided. 

 Ovary not lobed, the style terminal upon it; plants not with a mintlike odor, the 

 leaves not gland-dotted; corolla usually nearly regular. Flowers sessilo in 



spikes or heads VERBENACEAE (p. 239) . 



Ovary deeply 4-lobed, the style rising from between Ihe lobes; plants usually 

 with a mintlike odor, the leaves usually gland-dotted; corolla usually very 



irregular MENTHACEAE (p. 239). 



Fruit not composed of 2 or 4 nutlets, the nutlets either only ] or the fruit a capsule. 



Flowers reflexed and appressed to the stem in fiuit; fruit a single nutlet in the 



bottom of the calyx; calyx teeth hooked at the tip. Corolla purplish; 



leaves on Blender petioles PHRYMACEAE (p. 256) . 



Flowers not reflexed and appressed in fruit; fruit not a nutlet in the bottom of 

 the calyx; calyx teeth not hooked at the tip. 



