596 CONTRIBUTIOlSrS FROM THE NATIONAL HERBARIUM. 



cious or dioecious, variously arranged, usually regular; perianth commonly 

 small, sometimes showy, often wanting ; anthers 2-celled ; fruit usually capsular, 

 sometimes drupaceous, commonly 3-celled but often with fewer or more nu- 

 merous cells ; seeds frequently carunculate. 



A large family of plants, represented in Mexico also by numerous herbaceous 

 species. The sap usually has purgative and often poisonous properties. 

 Flowers surrounded by an involucre containing both pistillate and staminate 

 flowers ; perianth none or minute. 



Involucre cuplike, regular 1. EUPHORBIA. 



Involucre very irregular, oblique 2. PEDILANTHUS. 



Flowers not involucrate or, if so, the involucre containing only staminate or 

 pistillate flowers ; perianth present and usually well developed. 

 Ovules 2 in each cell ; stamens, at least the outer ones, opposite the sepals. 



Leaves all or mostly opposite 3. TETRACOCCUS. 



Leaves alternate. 



Fruit drupaceous ; flowers racemose, dioecious 4. HIERONYMA. 



Fruit capsular, rarely fleshy; flowers never racemose. 



Flowers monoecious 5. PHYLLANTHUS. 



Flowers dioecious 6. ASTROCASIA. 



Ovule 1 in each cell ; stamens, at least the outer ones, alternate with the 

 sepals. 

 Stamens in bud bent inward, the apex of the anther turned downward. 

 Staminate flowers usually with petals; flowers mostly in terminal 



racemes 7. CROTON. 



Stamens erect in bud. 

 A. Calyx lobes valvate. 



Petals present in the staminate flowers. 



Petals 8 to 12 ; stamens numerous 8. GARCIA. 



Petals 4 or 5 ; stamens 5 to 15. 



Petals entire ; stamens in 2 or 3 series 9. DITAXIS. 



Petals lobed; stamens in one series 10. CHIROPETALUM. 



Petals none. 



Stamens numerous, the filaments repeatedly branched ; leaves lobed. 



11. RICINUS. 

 Stamens few or numerous, the filaments simple ; leaves not lobed. 

 Styles united; plants usually with stinging hairs. 

 Inflorescence subtended by 2 large showy bracts ; stamens usu- 

 ally 20 to 30 12. DALECHAMPIA. 



Inflorescence with small inconspicuous bracts; stamens 3 or 



fewer 13. TRAGIA. 



Styles distinct ; plants without stinging hairs. 

 Anther cells elongate, often eylindric and curved, separated. 



14. ACALYPHA. 

 Anther cells globose, or oblong and adnate. 



Anther cells globose 15. BERNARDIA. 



Anther cells elongate. 



Leaves entire; styles lacerate 16. ADELIA. 



Leaves dentate; styles entire 17. ALCHORNEA. 



AA. Calyx lobes imbricate. 



Corolla present or, if absent, the plants with stinging hairs. 



18. JATROPHA. 

 Corolla none ; plants never with stinging hairs. 



Leaves deeply lobed 19. MANIHOT. 



