4")4 EUPHORBIACEvE. (SPURGE FAMILY.) 



red spot or red margins ; stipules triangular ; peduncles longer than the peti- 

 oles, collected in loose leafy terminal cymes ; appendages entire, larger and 

 white, or smaller and sometimes red ; pod glabrous, obtusely angled ; seeds ovate, 

 obtuse! i/ angled, wrinkled and tubercled (-" long), blackish. (E. hypericifolia 

 of Man., not L.) Common throughout the U. S. east of the plains. 



2. ZYGOPHYLLIDIUM. Leaves opposite, on short petioles, not oblique, 

 with stipular glands ; stems dichotomously branched, erect; cymes terminal ; 

 involucres with 5 glands ; seeds tuberculate. 



10. E. hexagona, Nutt. Somewhat hairy (1 high or more) ; branches 

 striate-angled ; leaves linear-lanceolate, entire ; involucre hairy without and 

 within ; glands with green ovate-triangular appendages twice their length ; 

 capsule smooth ; seeds ovate. Iowa to Tex., west to Col. and Montana. 



3. PETAL6MA. Uppermost leaves with conspicuous white petal-like mar- 

 gins, whorled or opposite, the others scattered ; erect annuals, with leaves equal 

 at base and entire, and with lanceolate deciduous stipules ; involucres 5-lobed, 

 in an umbel-like inflorescence. 



11. E. marginata, Pursh. Stem stout (2 -3 high), erect, hairy; leaves 

 sessile, ovate or oblong, acute ; umbel with 3 dichotomous rays ; glands of the 

 involucre with broad white appendages. Minn, to Mo., west to Col., also 

 spreading eastward to Ohio, and frequently escaped from gardens, where it is 

 often cultivated for its showy broadly white-margined floral leaves. 



4. TITHYMAL6PSIS. Only the uppermost leaves whorJed or opposite ; erect 

 perennials, with entire leaves equal at base ; stipules none ; involucres mostly 5- 

 lobed, in the forks of the branches and terminal ; inflorescence umbellifonn. 



12. E. COrollata, L. Glabrous or sometimes sparingly hairy (2-3 

 high); leaves ovate, lanceolate, or linear, entire, obtuse; umbel 5- -(3-7-) 

 forked, and the forks again 2-3- (or rarely 5-) forked; involucres long-pe- 

 duucled, with showy white appendages (appearing like petals), the lobes mi- 

 nute and incurved; pod slender-pedicelled, smooth ; seeds thick (1" long or 

 more), ash-colored, slightly uneven. Rich or sandy soil, N. Y. and N. J. to 

 Fla., west to Minn, and La., also adventive in Mass. July -Oct. 



B. Glands of the involucre without petaloid appendages. 



5. POINSETTIA. Involucres in terminal clusters, 4 -5-lobed, with few (or 

 often solitary) cup-shaped glands ; erect annuals, with variable, entire, den- 

 tate, or sinuate leaves, all or only the upper ones opposite; the uppermost 

 often colored, especially at base ; stipules small and glandular. 



13. E. dentata, Michx. Erect or ascending, hairy (1 high); leaves 

 ovate, lanceolate, or linear, petioled, coarsely toothed (1 -2' long), only the 

 lowest alternate, the upper often paler at base ; involucres almost sessile, with 

 5 oblong dentate lobes, and one or sometimes more short-stalked glands ; 

 seeds ovate-globular, slightly tubercled. Rich soil, Penn. to Tenn., Iowa. 

 E. Kan., and southward. July -Sept. 



14. E. heteroph^lla, L. Erect (1-3 high), glabrous; leaves alter- 

 nate, petioled, ovate-fiddle-shaped and sinuate-toothed, or lanceolate or linear 

 and entire, often only those of the branches linear ; the upper usually with a 



