720 EUPHORBIACEAE 



mm. long, sessile, bearing 3—4 crescent-shaped unappendaged glands prolonged into slen- 

 der horns : capsules globose-ovoid, 3 mm. in diameter, glabrous, the lobes rounded : seeds- 

 oblong or globose-oblong, barely 1.5 mm. long, terete, irregularly pitted. [Euphorbia 

 commutata Engelm.] 



On hillsides, chiefly along streams, Pennsylvania to Minnesota, Florida and Missouri. Spring and 

 summer. — A form occurring in Florida, known as T. commutata ericta (Norton) Small [Euphorbia com- 

 mutatayar. erecta Norton], is more erect in habit and has somewhat lanceolate leaf-blades. 



9. Tithymalus austrinus Small. Annual, bright green. Stem erect, 3-4 dm. tall, 

 commonly branched near the base, each branch topped by a several^rayed umbel : rays 

 dichotomous : leaves alternate ; blades linear, 1-5 cm. long, entire, acute : bracts sub- 

 tending the umbel a little broader than the leaf-blades : bracts of the rays opposite, del- 

 toid : involucres 1-1.5 mm. long : glands crescent-shaped, with slender horn-like processes : 

 capsules depressed, .3-3.5 mm. in diameter, glabrous, the lobes blunt: seeds ovoid, about 

 2 mm. long, reticulated. 



In pine woods, western Florida. Summer. 



10. Tithymalus P6plus (L. ) Hill. Annual, bright green, glabrous. Stem erect or 

 assurgent, 1-3 dm. tall, simple or branched from the base or above and topped by a 3-5- 

 rayed umbel : leaves alternate ; blades oblong or obovate, 1-4 cm. long, obtuse or retuse, 

 entire, more or less crisped, narrowed into slender petioles : bracts of the rays opposite, 

 ovate or triangular-ovate, minutely apiculate, sessile : involucres campanulate, almost 

 sessile in the axils of the bracts, 1-1.5 mm. high, bearing 4 crescent-shaped glands pro- 

 duced into subulate horns : capsules globose-ovoid, 2-3 mm. in diameter, slightly nodding, 

 smooth, the 3 lobes 2-keeled on the back : seeds oblong or oblong-ovoid, 1.5 mm. long, 

 whitish, nearly terete, marked with 1-4 series of pits. [Euphorbia Peplus L. ] 



In waste places, southern Canada to western New York, south to New Jersey, Pennsylvania, Ala- 

 bama and in California. Naturalized from Europe. Spring to fall. 



11. Tithymalus Peplidion (Engelm.) Small. Annual, glabrous. Stem simple 

 below or usually branched at the base ; branches erect or ascending, 5-20 cm. long, topped 

 by 3-rayed umbels : leaves alternate ; blades linear-.spatulate or spatulate, 8-25 mm. long, 

 entire, rounded or emarginate at the apex, at least near the base of the stem, narrowed into 

 slender bases : rays forked : bracts of the rays ovate to rhombic-lanceolate, inequilateral : 

 involucres turbinate, barely 1 mm. high, about as long as the peduncles or longer : glands 

 transversely oblong, about 0.5 mm. wide, furnished with 2 horn-like appendages : capsules 

 about 3 mm. broad, barely as high, lobes rounded, glabrous: seeds oblong, 1.3-1.5 mm. 

 long, the faces deeply pitted. [Euphorbia Peplidion Engelm.] 



In sandy and stony soil, Texas. 



12. Tithymalus tetraporus (Engelm.) Small. Annual, glabrous. Stem erect, 

 simple or branched at the base, the branches 1-2 dm. long, topped by 3-rayed umbels and 

 commonly branched below : leaves alternate ; blades spatulate, cuneate or oblong, obtuse 

 or notched at the apex, entire, narrowed into slender petioles or nearly sessile : rays forked : 

 bracts ovate or triangular, apiculate, sessile : involucres campanulate, 1.5 mm. high, nearly 

 sessile : glands transversely oblong, about 1 mm. broad, with 2 horn-like ajjpendages of 

 about the same length : capsules 3-lobed, 2-2.5 mm. broad, barely as high, glabrous, the 

 angles obtuse : seeds broadly oblong, 1.3-1.4 mm. long, minutely pitted, gray. [Euphorbia 

 tetrapora Engelm. ] 



In sandy soil, the Indian Territory to Georgia and Texas. Spring. 



13. Tithymalus trichotomus (PI. B.K.) Kl. & Garcke. Perennial, glabrous. Stem 

 commonly branched at the base, more or less woody at the base, the branches erect or ascend- 

 ing, 1-4 dm. tall, widely forking above : leaves numerous, rather approximate ; blades 

 thickish, cuneate to oblong, obtuse or acutish, 5-12 mm. long, minutely erose at maturity : 

 rays trichotomous : involucres campanulate, 2 mm. high, sessile or nearly so : glands obren- 

 iform, 1 mm. broad, yellow: capsules 3-lobed, 4 mm. wide, about k as high, the lobes 

 rounded : seeds subglobose, fully 1.5 mm. in diameter, white or pale gray, smooth. [Eu- 

 phorbia trichoto'ma H.B.K.] 



In sand, southern peninsular Florida and the Keys. Also in the West Indies and eastern Mexico. 



14. Tithymalus Roemerianus (Scheele) Small. Annual, glabrous. Stem erect, 2- 

 4 dm. tall, terete, simple or branched below, topped by a 3-rayed umbel, the rays forking : 

 leaves alternate, remote ; blades thin, spatulate-obovate or orbicular-spatulate below, 0.5- 

 2 cm. long, slightly emarginate, mucronate, serrulate near the apex, glaucescent beneath : 

 bracts of the rays half-orbicular, crenate to about the middle : bracts subtending the umbel 

 ovate, al)out 1.5-2 cm. long, obtuse: involucres campanulate, 1.5-2 mm. long: glands 

 broad, furnished with 2 incurved horn-like processes : capsules subglobose, 3 mm. broad, 

 smooth; lobes keeled: seeds oblong-ovoid, 1.6-1.8 mm. long, gray, irregularly pitted. 

 [Euphorbia Roemeriana Scheele.] 



In woods, southern Texas. 



