EUPHORBIACEAE. 235 



repand-dentate, compressed on the margin; spines short, thick, divergent, 4-6 

 mm. long. 



Widely established in many places, often forming dense thickets, New Provi- 

 dence, Cat Island, Watling's, Long Island and Inagua : Florida ; West Indies ; 

 Mexico. Naturalized from India and the Moluccas. Referred by Hitchcock and 

 Mrs. Northrop to Euphorbia antiquorum L. MOTTLED SPURGE. 



27. ARTHROTHAMNTJS Kl. & Gke. Monats. Akad. Berlin 1859: 251. 1859. 



Leafless, shrubby plants with jointed branches. Involucres not subtended 

 by dilated bractlets. Leaves reduced to opposite sessile scales glandular on 

 both surfaces; stipules none. Involucres minute, terminal, campanulate, dioe- 

 cious, minutely bibracteate at the base. Glands transverse, thick, orbicular or 

 semiorbicular, spreading, plane, entire. Bracteoles plumose. Styles 3, bifid, 

 revolute. Seeds ovate-tetragonal, scrobiculate. [Greek, jointed bush.] About 

 10 species, of tropical America and southern Africa. Type species: Euphorbia 

 Tirucalli L. 



1. Arthrothamnus cassythoides (Boiss.) Millsp. Field Mus. Bot. 2: 306. 1909. 

 Euphorbia cassythoides Boiss. Cent. Euph. 20. 1860. 



Plant 1-2 m. high, the branches white-barked, verticillate below, dichotomous 

 above; branches with internodes 8-15 cm. long and 6-7-angled, the nodes 

 gummy. Cymes terminal, dichotomous; involucres produced between small 

 thick triangular bracelets; tube short-campanulate, glabrous within; lobes 

 triangular-ovate, 4-5-dentate, hairy; glands fleshy; styles short, hairy, bilobate 

 at the apex; capsule ovoid; cocci subcarinate; seeds white, each facet 2-3- 

 foveolate. 



Sandy soil near Deep and Fresh Creeks, Andros : Cuba. LEAFLESS CUBAN 

 SPURGE. 



28. TITHYMALUS [Tourn.] Adans. Tarn. 2: 355. 1763. 



Annual or perennial milky herbs or shrubby plants with simple or branched 

 stems topped by several-rayed cyme-like umbels. Leaves below the umbel 

 scattered or alternate, estipulate, often broadened upward; bracts of the umbel 

 quite different from the stem-leaves, entire or toothed. Involucres sessile or 

 peduncled, the lobes often toothed; glands 4, transversely oblong and appearing 

 reniform by the cornuate extremities or appendages. Capsule smooth or 

 tuberculate; cocci rounded or more or less carinate. Seeds variously pitted, 

 often carunculate. [Greek, referring to the milky juice.] About 250 species, 

 of wide geographic distribution.,. Type species: Euphorbia dendroides L. 



1. Tithymalus trichotomus (H.B.K.) Kl. & Gke. Monats. Akad. Berlin 1860: 

 81. 1860. 



Euphorbia trichotoma H.B.K Nov. Gen. 2: 60. 1817. 



Perennial, glabrous. Stem commonly branched and more or less woody at 

 the base, the branches erect or ascending, 1-4 dm. tall, widely forking above. 

 Leaves numerous, rather approximate, small, thickish, cuneate to oblong, obtuse 

 or acutish, 5-12 mm. long, minutely erose when mature; inflorescence trich- 

 otomous; involucres campanulate, sessile or nearly so, 2 mm. long; glands 

 reniform, 1 mm. long, yellow; capsule tricoccous, the cocci rounded; seeds 

 white, globose, 2 mm. in diameter, smooth; caruncle thin, circular. 



Coastal sands. Allen's Cay, Great Bahama and Andros : Florida ; Cuba ; the 

 Cayman Islands. FORKING SPURGE. 



