EUPHORBIACE^E. (SPURGE FAMILY.) 433 



§2. PETALOMA. Uppermost or floral haves with conspicuous white petal-like 

 margins, ichor led or opposite, the others scattered: erect annuals, with the leaves 

 equal at the ba>e and entire, and with lanceolate deciduous stipules : involucres 

 mostly 5-lobed, collected in an umbel-like inflorescence : no caruncle to the seed. 



9. E. mabginAta, 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. — Frequently cultivated in gardens for 



ts showy broadly white-margined floral leaves : native of the plains of Kansas 



and Nebraska. 



§ 3. TITH YMALOPSIS. Only the uppermost or floral leaves whorled or opposite : 

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

 mostly 5-lobed, in the forks of the branches and terminal, in an umbelliform inflo- 

 rescence : seeds without caruncle. 



10. E. COrollata, L. Glabrous or sometimes sparingly hairy (2° -3° high) ; 

 leaves ovate, lanceolate, or lineai', entire, obtuse ; umbel 5- (3 - T-) 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 

 siightly 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. EX APPEND ICULAT^E. Glands of the involucre without petaloid appendages. 



§4. POINSETTIA. Involucrps in terminal clusters, 4 - b-Lobed, with few (or 

 often solitary) cup-shaped glands: 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. ovate-fiddle-shaped and sinuate-toothed, or lanceolate or linear and en- 

 tire, often only those of the branches linear ; the upper ones usually Avith 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, Jacq.) — Slopes and rocky soil, W. Illinois and southward. 

 July - Sept. 



§ 5. TITHYMALUS. Involucres in a terminal dichotomous or commonly umbelli- 

 form inflorescence, 5- or usually <±-lobed, with as many flat or convex entire or 

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

 glabrous (except No. 15) annuals or perennials; with entire or serrulate leaves, 

 ana no stipules. 



* Perennials with entire leaves, all or only the upper ones opposite : involucres cany- 



GM 19 



