COMPOSITE. 55 



the limb of the calyx or pappus. Seed destitute of albumen. Radicle 

 short : cotyledons flat or plano-convex. — Herbs, rarely shrubs or trees 

 (forming about one-tenth of phanerogamous vegetation) ; with alternate 

 or opposite sometimes divided or lobed exstipulate leaves. Branches 

 often corymbose, terminated by the heads, the central ones earliest 

 developed. Flowers in each head expanding successively from the 

 margin (or lower portion) to the centre or apex, either all of the same 

 color (homochromous), or the marginal ones different from those of the 

 disk (heterochromoiis), the latter in this case almost always yellow ; 

 either perfect, polygamous, or diclinous. 



There are several terms nearly peculiar to this order, or employed in a particular 

 sense. The head has been termed by different authors the Calathidmvr , Anthodium, 

 or Cephakinthhim ; the involucre has received the name of Covimon calyr, Pericli- 

 niuvi, <^c. ; and the receptacle has been called the Phoranthhim , Clinanthmm, or 

 Rachis : we have employed none of these tenns. The head is said to be homoga^ 

 rnmts, when all the flowers are perfect ; or hcterogawous^ when the marginal ones are 

 pistillate or neutral, and the others perfect or staminate : it is termed aiscoid, when 

 the corolla is tubular throvighout ; ligvlatc, when all the corollas are ligulate ; radiate, 

 when the marginal ones only are ligulate and the others tubular ; and fa b^dy discoid, 

 when the corollas are all bilabiate : they are monaciovs, when the staminate and pis- 

 tillate flowers occupy the same heads; hetcroccp/ialovs, when they occupy different 

 heads upon the same individual ; dia-ciovs, when in separate heads upon different in- 

 dividuals. The modified leaves of the involucre are called scaks. The receptacle, 

 which is the axis of a contracted or depressed spike (and therefore very properly 

 termed raehis, by Lessing), is said to be j^ckaccoiis or chajfjf, when all the flowers 

 are subtended by chaffy scales {bractcoks, Lessing), similar to the innermost scales 

 of the involucre; semipakaccaiis, when only partly furnished with chaffy scales, and 

 epakaceoKS or naked, when destitute of these scales : it is alreokitc, when each flower 

 is surrounded at the base with a veiy short scaly ring or involucel, so as to present 

 an appearance like honey-comb wlien the achenia are removed ; fimhrilkitc, when 

 the margins of the alveoli are irregularly lacerate or bristly ; areolaie when a slight 

 or obsolete, often pentagonal, border or line surrounds the base of each flower. "1 he 

 anthers are usually more or less prolonged at the summit into a membranous ap- 

 pendage {appr.ndiailate^ ; and sometimes each lobe or cell bears a subulate or seti- 

 form appendage at the base, when they are said to be caudate. The achenia are 

 articulated with the receptacle, either sessile or stipitate : they are sometimes ros- 

 trate, or with the summit prolonged into a beak ; in which case the pappus is often, 

 but incorrectly, said to be stipitate. — For the sake of greater convenience in the study 

 of this vast family, we introduce a synopsis of its leading divisions; and give, at 

 the commencement of each tribe, a conspectus of its subdivisions and genera, so 

 far as they are represented in the flora of North America. This is the more neces- 

 sary, since the student may at first meet with some difficulty in the application of the 

 leading technical characters of the tribes, derived from the form of the styles and 

 stigmas. 



CONSPECTUS OF THE TRIBES. 



Suborder I. TUBULIFLOR.iE.— Corolla of the perfect flowers tubular, and 

 regularly 5- (rarely 3-4-) toothed or lobed. 



Tribe I. Vernoniace.e. Style of the perfect flowers cylindraceous ; the branches 

 usually elongated and subulate, hispid throughout; the stigmatic lines not 

 extending beyond thelv liiiddle. 



Tribe II. EupiToniACEi^. Style of the perfect flowers cylindraceous; the branches 

 elongated, obtuse or clavate, externally puberulent or papillose towards the 

 siunmit ; the stigmatic lines obscure, termmating near their middle. 



