476 



EUPHORBIACEAE. 



Vol. II. 



17. POINSETTIA Graham, Edinb. N. Phil. Journ. 20: 412. 1836. 



Annual or perennial herbs or shrubby plants, with green or partially, often more highly 

 colored, foliage. Stems simple or branched, often irregularly so. Leaves alternate below, 

 opposite above, similar throughout or very variable; stipules gland-like. Involucres in axil- 

 lary or terminal cymes or solitary; lobes fimbriate. Glands fleshy, solitary, or rarely 3 or 4, 

 sessile or short-stalked, without appendages, the missing ones represented by narrow lobes. 

 Capsule e.xserted, the lobes rounded. Seed narrowed upward, tuberculate, without a caruncle 

 or with a minute one only. [In honor of Joel Roberts Poinsette, of South Carolina.] 



About 12 species, mostly natives of tropical America. Type species: Poinsettia pulcherrima 

 (Willd.) Graham. 



Glands of the involucre stalked ; leaves nearly or quite uniform. 



Leaves linear or linear-lanceolate ; seeds narrowly ovoid, not prominently tuberculate. 



1. P.cuphosperma. 

 Leaves ovate or ovate-lanceolate ; seeds broadly ovoid, prominently tuberculate, 



2. P. dentata. 

 Glands of the involucre sessile ; leaves various. 3. P, heterophylla. 



Poinsettia cuphosperma (Engelm.) Small. Warty Spurge. Fig. 2766. 



Euphorbia dentata var. cuphosperma Engelm. Bot. Mex. 

 Bound. Surv. 190. 1859. 



Euphorbia cuphosperma Boiss. in DC. Prodr. 15 : Part 

 2, yi. 1862. 



Poinsettia cuphosperma Small, Fl. SE. U. S. 721. 1903. 



Annual, usually sparingly pubescent. Stem erect, 

 slender, simple, or sparingly branched, 8-15' high. 

 Leaves opposite or alternate, linear, oblong, or linear- 

 lanceolate, io"-3' long, entire, undulate, or denticu- 

 late, narrowed into a slender petiole; involucres 

 crowded at the ends of the branches, nearly sessile, 

 glabrous, or nearly so, nearly 2" long, bearing about 

 4 long-stalked unappendaged glands; capsule gla- 

 brous, or sparingly pubescent, 2\" m diameter, seeds 

 narrowly ovoid, about li" long, irregularly 4-angled, 

 ridged and slightly tuberculate. 



South Dakota to Colorado and Mexico Aug-Sept. 



2. Poinsettia dentata (Michx.) SmaH. 

 Toothed Spurge. Fig. 2767. 



Euphorbia dentata Michx Fl. Bor. Am. 2 : 211. 1803. 

 Poinsettia dentata Small, Fl. SE. U. S. 722. 1903. 



Annual, dull green, pubescent. Stem erect or 

 ascending, 8'-i5' high, somewhat woody below, 

 branched, the branches mostly ascending; leaves 

 opposite, or the lowest alternate, varying from 

 ovate to nearly linear or orbicular-oblong, s"-3i' 

 long, coarsely dentate, narrowed into slender 

 petioles, the nerves prominent beneath ; involucres 

 clustered at the ends of the branches, oblong- 

 campanulate, about li" long, 3-5-lobed, bearing 

 1-4 yellowish short-stalked glands without ap- 

 pendages ; capsule glabrous, 2"-2J" in diameter ; 

 seeds ovoid or ovoid-globose, ash-colored, irregu- 

 larly tuberculate, inconspicuously 4-angled. 



In dry or moist soil, Pennsylvania to South Da- 

 kota, Wyoming, Tennessee, Louisiana and Mexico. 

 July-Oct. 



