564 226. COMPOSITAE 



Fruits not very hard, 3-angled, usually tubercled. Herbs or under- 

 shrubs. Heads solitary 206 



206. Involucral bracts in one row or in two indistinct rows. (See 124.) 



Dimorphotheca Moench 

 Involucral bracts in several rows. Ray-flowers blue or white. Leaves 

 pinnately divided. — Species 6. South Africa. Some are used medi- 

 cinally Garuleum Cass. 



207. (201.) Receptacle covered with chaffy scales 208 



Receptacle glabrous or hairy, without scales between the flowers. . . 213 



208. Heads with the inner flowers male (apparently hermaphrodite), the 



outer female and provided with a more or less strap-shaped, rarely a 



thread-shaped corolla 209 



Heads unisexual, some with all the flowers male (apparently hermaphrod- 

 ite), the others with all the flowers female and provided with a tubular 

 corolla or without a corolla 211 



209. Involucral bracts in one row, united below when young. Outer fruits 



hairy, without a pappus, the inner with a pappus of numerous one- 

 ranked bearded bristles. Heads soHtary. Shrubs. — Species i. 

 South Africa. (Under Eriocephalus L.) . . . . Lasiocoma Bolus 

 Involucral bracts in two or more rows. Pappus of 2 — 3 bristles or want- 

 ing 210 



210. Involucral bracts all alike. Corolla of the female flowers 2-toothed. 



Pappus of the outer fruits of 2 — 3 bristles. Heads in panicles. — 

 Species i. Naturalized in tropical and South Africa. Used medicinally. 



Parthenium L. 



Involucral bracts of two kinds, the inner united below. Corolla of the 



female flowers entire or 3-toothed. Pappus none. Heads in racemes 



or umbels, or solitary. — Species 20. South Africa to Damaraland. 



Some are used medicinally Eriocephalus L. 



211. Heads dioecious, many-flowered. Involucral bracts in 3 rows. Corolla 



4-toothed, yellow. Anthers cohering, auricled at the base. Style cleft. 

 Fruits hairy. Pappus of 2 — 3 bristles. Trees. Leaves opposite. 

 Heads in leafy panicles. — Species 2. Island of St. Helena. 



Petrobium R. Br. 

 Heads monoecious, the male many-flowered with a 5-toothed corolla, 

 the female i — 2-flowered with an involucre of partly united bracts» and 

 without a corolla. Anthers free or slightly cohering, entire at the base. 

 Style of the male flowers undivided. Pappus none. Herbs or under- 

 shrubs. [Tribe HELIANTHEAE, subtribe ambrosinae.] . . 212 



212. Involucral bracts of the male heads free. Filaments united. Female heads 



2-flowered. Heads solitary or in glomerules in the axils of the leaves. — 

 Species 4. North and Central Africa and Mascarene Islands ; natural- 

 ized in South Africa. They yield dyes and medicaments and are noxious 

 to pasturing cattle Xanthium L. 



