EUPHORBIACE^.. (SPURGE FAMILY.) 433 



§ 2. PETALOMA. Uppermost or floral leaves with rompirnous white petal-like 

 margins, whorl ed or opposite, the others scattered: erect annuals, with the leaves 

 equal at the ba^e and entire, and with lanceolate d(ciduous stipules: involucres 

 mostlij ^^-lobid, collected in an umbil-like inflorescence : no caruncle to the seed. 



9. E. jMauginXta, Pursh. Stem stout (2°-3° hiy,h), erect, hairy; leaves 

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

 involucre witW broad white appendages. — Frequently cultivated in gardens for 

 its showy bimdly white-iuargined floral leaves : native of the plains of Kansas 

 and Nebraska. 



§ 3. TITH YM AL6PSIS. Onlij the uppermost or floral leaves whorled or opposite : 

 erect perennials, ivith entire leaves equal at the base : stipules none : involucres 

 mosthi 5-lobed, in thefl)rks of the branches and terminal, in an umbellifl)nn inflo- 

 rescence : seeds without caruncle. 



10. 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-peduncled ; pod 

 slender-pedicelled, smooth ; seeds thick (1" long or more), ash-colored, the surface 

 slightly uneven. — Rich or sandy soil, New York to Wisconsin and southward. 

 July - Oct. — Conspicuous for the showy false lobes of the involucre, which ap- 

 pear like five white petals, the true lobes minute and incurved. . 



B. EXAPPENDICULATJE. Glands of the involucre without petal oid appendacjcs. 



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

 oflen solitarij) cup-shaped (/lands: seed without a caruncle: ours erect annuals, 

 with variable, entire, dentate, or sinuate leaves, all of them or only the upper ones 

 opposite ; the uppermost often colored, especially at the base : stipules small and 

 glandular. 



11. E. dentata, Michx. Erect or ascending, hairy (1° high) ; leaves ovate, 

 lanceolate, or linear, petioled, coarsely toothed (l'-2' long), only the lowest ones 

 alternate, all others opposite, upper ones 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 Illinois and 

 southward. July - Sept. 



12. E. heterophylla, L. Erect (1°- 3° high), glabrous; leaves alternate, 

 petioled, ovatc-ful die-shaped and sinuate-toothed, or lanceolate or linear and en- 

 tire, often only those of the branches linear ; the upper ones usually with a red 

 base ; involucres about the length of the peduncle, with 5 ovate incised lobes 

 and a single or few and almost sessile glands : seeds nearly globular, tubercled. 

 (E. cyathophora, ./ficy.) — Slopes and rocky soil, W. Illinois and southward. 

 July - Sept. 



§ 5. TITHYMALUS. Involucres in a terminal dichotomous or cowmonli/ nmbelli- 

 form inflorescence, !j- or usually A-lobed, with as many flat or convex entire or 

 crescent-shaped glands : seeds mostly carunculate: ours ascending or erect, and 

 glabrous {except No. \5) annuals or perennials ; ivith entire or serrulate leaves, 

 and no stipules. 



♦ Perennials with entire kaves, all or only the upper ones opjwsite : involucres tong- 

 G M 19 



