222 EUPHORBIACEAE. 



Family 78. EUPHORBIACEAE St. Hill. SPURGE FAMILY. 



Flowers not in an involucre ; calyx of several sepals. 

 Petals present, at least in the staminate flowers. 



Stamens 6; filaments distinct. i. CROTON. 



Stamens 10; filaments monadelphous. 2. DITAXIS. 



Corolla wanting ; stamens 1-3. 3. TRAGIA. 



Flowers in involucres ; calyx represented by minute scales at the base of filament- 

 like pedicels. 

 Glands of the involucres with petal-like appendages ; these however sometimes 



much reduced. 

 Leaves all opposite. 



Glands of the involucres 4 ; leaves inequilateral, usually oblique at the base. 



4. CHAMAESYCE. 

 Glands of the involucres 5 ; leaves equilateral, not oblique at the base. 



5. ZYGOPHYLLIDIUM. 



Leaves alternate or scattered, at least below the inflorescence ; bracts petal- 

 like. 6. DlCHROPHYLLUM. 



Glands of the inflorescence without petal-like appendages ; entirely naked 



or with a crescent-like horn. 

 Stern topped by an umbel ; stipules none ; involucres in open cymes, each 



with 4 glands and entire or toothed lobes. 7. TITHYMALUS. 



Stem not topped by an umbel ; stipules gland-like ; involucres in cluster-like 

 cymes ; each with a single gland or rarely with 4 glands and fimbriate lobes. 



8. POINSETTIA. 

 i. CROTON L. 



i. Croton texensis (Klotzsch) Muell. Arg. In sandy soil from 111. and 

 Wyo. to Ala. and Ariz.; also in Mex. Alt. 4000-6000 ft. New Windsor; 

 Crow Creek; Canon City; Longmont; Boulder; La Salle. 



2. DITAXIS Vahl. 



i. Ditaxis humilis (Engelm. & Gray) Pax. (Argythamnia humilis Muell.) 

 On prairies from Kans. and Colo, to La. and Tex. " Southern Colorado." 



3. TRAGIA. 



i. Tragia ramosa Torn In dry soil from Mo. and Colo, to Tex. and Ariz. ; 

 also Mex. Alt. 4000-6000 ft. Boulder ; Denver ; Castle Rock ; Larimer Co. ; 

 Arboles; Walsenburg; Trinidad; Horsetooth Gulch; Spring Canon; gulch 

 west of Pennock's; Ute Creek; Pennock's; Spring Canon. 



4. CHAMAESYCE S. F. Gray. SPURGE. 

 Leaves entire. 



Annuals or biennials. 



Plants prostrate; leaf-blades nearly orbicular. i. C. serpens. 



Plants more or less ascending or erect ; leaf-blades linear or linear-lanceolate. 

 Capsule less than 1.5 mm. long. 2. C. revoluta. 



Capsule about 2 mm. long or more. 



Appendages of the glands conspicuous, white. 3. C. petaloidea. 



Appendages inconspicuous, greenish-white, or obsolete. 



4. C. flagelliformis. 

 Perennials. 



Leaves glabrous. 



Glands transversely oval ; appendages fan-shaped, white, petalloid. 



5. C. albomarginata. 

 Glands oval ; appendages crescent-shaped, much narrower than the gland, 



greenish. 6. C. Fendleri. 



Leaves pubescent. 7. C. lata. 



