394 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Flowers in crowded spikelike clusters, 

 terminal or axillary, the pistillate 

 usually below; petals small and 

 inconspicuous, often wanting in 

 the pistillate flowers. 



Stamens 10, monadelphous 10. Ditaxis (p. 401). 



Stamens 6, the filaments distinct.. .11. Croton (p. 402). 

 Petals wanting in all flowers. 

 Stamens numerous, 8 to 20. 



Shrubs; stigmas 2-cleft 15. Bernardia (p. 405). 



Herbs; stigmas dissected 12. Acalypha (p. 403). 



Stamens few, 2 to 5. 



Plants slender, small, covered with 

 stinging hairs; capsules pedi- 



celed 13. Tragia (p. 404). 



Plants stout, much larger, glabrous; 



capsules sessile 14. Stillingia (p. 404). 



1. POINSETTIA Graham. Poinsettia. 



Annuals, 30 to 60 cm. high, the stems simple or branched from the base; upper 

 leaves often colored, alternate below, opposite above; stipules glandlike; involucres 

 in axillary or terminal cymes or solitary, the lobes fimbriate; glands fleshy, solitary 

 or rarely 3 or 4, sessile or short-stalked, without appendages, the missing ones repre- 

 sented by narrow lobes; capsules exserted; seeds narrowed above, tuberculate or 

 roughened. 



KEY TO THE SPECIES. 



Glands of the involucre sessile or nearly so; leaves discolored at 



the base; plants glabrous 1. P. havanensis. 



Glands of the involucre stalked; bracts and leaves not dis- 

 colored; plants more or less pubescent. 

 Leaf blades linear to linear- lanceo late ; seeds not promi- 

 nently tuberculate; glands of the involucre 3 or 4. . . 2. P. cuphosperma. 

 Leaf blades ovate to ovate-lanceolate; seeds prominently 



tuberculate; glands of the involucre solitary 3. P. dentata. 



1. Poinsettia havanensis (Willd.) Small, Fl. Southeast. U. S. 722. 1903. 

 Euphorbia havanensis Willd.; Boiss. in DC. Prodr. 15 2 : 73. 1862. 



Type locality: Cuba. 



Range : Southeastern United States to Arizona and in tropical America. 



New Mexico: Organ Mountains. 



2. Poinsettia cuphosperma (Engelm.) Small, Fl. Southeast. U. S. 721. 1903. 

 Euphorbia dentata cuphosperma Engelm. in Torr. U. S. & Mex. Bound. Bot. 190. 



1859. 

 Euphorbia cuphosperma Boiss. in DC. Prodr. 15 2 : 73. 1862. 

 Type locality: Copper Mines, New Mexico. Type collected by Wright (no. 



1834). 

 Range: Wyoming and South Dakota to Texas. 



New Mexico: Upper Pecos River; Santa Rita; Organ Mountains; Roswell; White 

 Mountains. Dry, open slopes, in the Upper Sonoran Zone. 



3. Poinsettia dentata (Michx.) Klotzsch & Garcke, Monatsb. Preuss. Akad. Wiss. 



Berlin 1859: 253. 1859. 

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

 Type locality: "Hab. in Tennassee." 



