This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial herbs, with tough rootstocks and glabrous or pubescent foliage. Stems solitary or tufted, topped by several-rayed umbels. Leaves alternate or scattered below the umbels, thence opposite or whorled, entire, more or less leathery, inclined to be revolute. Involucres sessile or peduncled, few and remote, or in rather close clusters and numerous; lobes toothed or fimbriate Glands sessile or stalked, with white, pink or rose petal-like appendages. Capsule exserted, sometimes conspicuously so, often broader than high; lobes rounded. Seeds narrowed upward, more or less conspicuously punctate, without caruncles. [Greek, resembling Tithymahis.]
About 18 species, natives of North America. Type species: Tithymalopsis corolláta (L.) Kl. & Garcke.
Involucres with conspicuous petaloid white or pinkish appendages.
Stems simple below or nearly so, umbellately or paniculately branched above.
Stems tufted or diffusely branched below, dichotomous above.
Leaves linear-lanceolate to linear: rootstock horizontal.
Leaves ovate, oval or oblong; rootstock perpendicular.
Involucres with inconspicuous green appendages.
Euphorbia corollata L. Sp. Pl. 459. 1753. Tithymalopsis corollata Kl. & Garcke, Monatsb.
Akad. Ber. 1859: 249.
Perennial by a long stout rootstock, bright green, glabrous or somewhat pubescent. Stem erect, 10'-3° tall, often spotted, usually simple; umbellately or paniculately branched above; leaves linear, oblong or oblong-spatulate, 10"-20" long, entire, short-petioled or sessile, the lower scattered, those subtending the umbel verticillate; rays of the umbel forked; bracts ovate to linear, green; involucres mostly terminal, less than 1" long, bearing 4 or 5 yellowish green oblong glands subtended by white petallike cuneate or orbicular-cuneate appendages; capsule erect, subglobose, 1"-2" in diameter; seeds ovoid, smooth, sparingly pitted.
In dry soil, Ontario to Massachusetts. Minnesota, Kansas, Florida and Texas. April-Oct. Ascends to 4200 ft. in North Carolina. Apple-, bowman- or purging-root. Picac. Milk- or white purslane. Milk-pusley or-ipecac. Milkweed. Snake-milk. Wild hippo. Naturalized in its northeastern range.
Euphorbia marylandica Greene, Pittonia 3: 345. 1898.
Perennial, with horizontal rootstocks, glabrous, pale green, glaucescent. Stems tri-chotomous near the base, thence bushy, 16' tall or less, the branches dichotomous; leaves linear to linear-lanceolate, 3/4'- 1 1/2' long, acute, opposite above the whorl of 3 at the first fork; involucres hemispheric, nearly 1" high, rather short-peduncled; appendages white, suborbicular to reniform.
Euphorbia arundelana Bartlett, Rhodora 13: 364. 1911.
Perennial, with perpendicular stout rootstocks, glabrous or pubescent, bright green. Stems tufted as in T. Ipeca-cuanhae, stout, 8' tall or less, dichotomous or trichotomous above; leaves scale-like on the lower part of the stems, the upper ones mostly 1' long or less, ovate, oval or oblong, obtuse; involucres hemispheric, about 1" high, those on the lower part of the stem very long-peduncled, the upper ones shorter-peduncled; appendages white or pink, suborbicular.
In sandy places, Anne Arundel County, Maryland. May-June.
Euphorbia Ipecacuanhae L. Sp. Pl. 455. 1753. Tithymalopsis Ipecacuanhae Small, Fl. SE. U. S. 716. 1903
Perennial by a deep perpendicular root, glabrous or pubescent. Stems several or many, slender, spreading, ascending or nearly erect, 4'-10' long, branched; leaves green or red, wonderfully variable in outline from linear to orbicular, 5 '-3' long, mostly opposite, entire, the upper sometimes whorled, the lower often alternate, short-petioled; involucres axillary, mostly hemispheric, nearly 1" long, slender-peduncled; bearing 5 transversely elliptic or oblong green sessile unappendaged glands; capsule 1 1/2" in diameter, nodding; seeds light gray, oblong-ovoid or ovoid, 1 /2" long, pitted, obscurely 4-sided.