4')4 EUPHORBIACE^. (SPURGE FAMILY.) 



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

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

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

 obtusely angled, wrinkled and tubercled (^" long), blackish. (E. hypericifolia 

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



§ 2. ZYGOPHYLLfDIUM. Leaves opposite, on short petioles, not oblique, 

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

 involucres with h 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. PETALOMA. 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. TITH YMAL6PSIS. Only the uppermost leaves whorled 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 umbeUiform. 



12. E. COroUata, 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- 

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

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

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

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



B. Glands of the involucre without petaloid appendages. 



§5. POIXSETTIA. 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), o?«/// the 

 loicest 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^Ua, L. Erect (l-3° high), glabrous; leaves alter- 

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

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



