WOOTON AND STANDLEY FLORA OF NEW MEXICO. 393 



81. EUPHORBIACEAE. Spurge Family. 



Monoecious or dioecious herbs or shrubs with acrid or milky sap; leaves simple, 

 sessile or petiolate, alternate or opposite; stipules present or wanting; inflorescence 

 various, the flowers involucrate in one section, the involucre resembling a calyx 

 and the true calyx much reduced; number of parts of the perianth varying in the 

 staminate and pistillate flowers in the same species; corolla often wanting, especially 

 in pistillate flowers; stamens few or numerous, variously united or distinct; ovary 

 usually 3-celled, with 1 or 2 ovules in each cell; fruit mostly a 3-celled capsule, 

 separating at maturity into three 2-valved carpels each containing 2 or mostly 1 large 

 seed. 



KEY TO THE GENERA. 



Flowers involucrate; calyx represented by a minute 

 scale at the base of a filament-like pedicel. 

 Glands of the involucre without petaloid ap- 

 pendages, naked, sometimes with crescent- 

 shaped horns. 

 Stems not terminated by an umbel; stipules 

 glandlike; involucres cymose-clus- 

 tered, each with a single gland or 

 rarely with 4 glands and fimbriate 



lobes 1 . Poinsettia (p. 394). 



Stems terminating in an umbel; stipules 

 none; involucres in open cymes, 

 each with 4 glands and entire or 



toothed lobes 2. Tithymalus (p. 395). 



Glands of the involucres with petaloid append- 

 ages, these sometimes much reduced. 

 Leaves alternate or scattered, at least below 

 the inflorescence. 

 Perennials; stipules wanting; bracts not 



petaloid; leaves small, narrow 3. TrrnYMALOPSis (p. 396). 



Annuals or biennials; stipules narrow: 

 bracts petaloid; leaves large and 

 broad (those of the inflorescence 



variegated) I. Dichrophyllt/m p. 396 



Leaves all opposite. 



Leaf blades not oblique at the base; 



ires mostly rather large 5. ZYGOPHYixronrM 



Leaf blades oblique al the base; 1 



mostly small 6. Chamaesycj p 



Flowers not involucrate; calyx of Beveral sepals. 

 Ovules and Beeds2 iii each cell. 



Annual; Btamens2; filaments distind 7. Rbvebchonia (p. 401). 



Perennial; stamens :;; filaments parti] 



united s . I'uvi i wun - p. M)l). 



Ovules ami seeds solitary in each cell. 



Petals present, al Least in the staminate 

 Mowers. 

 Flowers in terminal cymes; petals con- 

 spicuous 9. Jatrophi p. I'M). 



