WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 393 
81. EUPHORBIACEAE. Spurge Family. 
Moneccious or dicecious 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....-...- 222-22 ee eee ee eee eee eee 1. Pornsertta (p. 394). 
Stems terminating in an umbel; stipules 
none; involucres in open cymes, 
each with 4 glands and entire or 
toothed lobes......-..----------++++++ 2. TrTHYMALUS (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. TrTHYMALOPSIS (p. 396). 
Annuals or biennials; stipules narrow; 
bracts petaloid; leaves large and 
broad (those of the inflorescence 
variegated).....--++-------+-+-+- 4, DicHROPHYLLUM (p. 396). 
Leaves all opposite. 
Leaf blades not oblique at the base; 
leaves mostly rather large........ 5. ZYGOPHYLLIDIUM (p. 397). 
Leaf blades oblique at the base; leaves 
mostly small.............-------- 6. CHAMAESYCE (p. 397). 
Flowers not involucrate; calyx of several sepals. 
Ovules and seeds 2 in each cell. 
Annual; stamens 2; filaments distinct... .-.- 7. ReEvERCcHONIA (p. 401). 
Perennial; stamens 3; filaments partly 
united.......----.0.022e ee eee eee eee 8. PHYLLANTHUS (p. 401). 
Ovules and seeds solitary in each cell. 
Petals present, at least in the staminate 
flowers. 
Flowers in terminal cymes; petals con- 
SPicuOUS.....-.---.---ee eee eee ee 9. JaTropua (p. 401). 
