Erechtites. composite. 433 



Subtribe 8. Senecioneje, Cass., DC. — Heads homogamous or hetero- 

 gamous, never dioecious, discoid or radiate ; the rays ligulate, in a single 

 series. Receptacle scarcely ever chaffy. Anthers not caudate. Pappus 

 capillary. 



CONSPECTUS OF THE GENERA. 



Div. 1. Erechtiteje. — Heads discoid, heterogamous ; the flowers all tubular. 



161. Erechtites. Marginal flowers pistillate, very slender, 2-3-toothed. 



Div. 2. EusenecionejE. — Heads homogamous, or heterogamous and radiate. 



• Scales of the involucre in one or two series. 



+■ Leaves alternate. 



162. Cacalia. Heads discoid, 5-many-flowered. Achenia glabrous. Pappus 



scabrous. Flowers white or whitish. 



163. Senecio. Heads radiate or discoid, many-flowered. Pappusof very slender 



bristles. Receptacle flat or convex. Flowers mosdy yellow. 



164. Tetrauymia. Heads discoid, 4- (rarely 5-9-) flowered. Pappus of copious 



denticulate bristles. Achenia villous with long denticulate hairs. Re- 

 ceptacle small. 



165. Crocidium. Heads radiate, many-flowered. Pappus of the disk-flowers 



barbellate, caducous; of the ray none ! Receptacle conical ! 



+■ -t- Leaves opposite. 



166. Arnica. Heads radiate, many-flowered. Pappus barbellate or strongly 



denticulate, rather rigid. Receptacle flat. 



* * Involucre imbricated. 



167. Lessingia. Heads discoid, many-flowered, homogamous; the marginal 



flowers larger and radiatiform, deeply 5-lobed. Pappus scabrous, rather 

 rigid. Achenia silky-villous. 



Div. 1. Erechtites, DC— Flowers discoid, heterogamous; the 

 marginal flowers tubular, pistillate. 



161. EPvECHTITES. Raf. {fl. Ludov. p. 65.? excl. char.) ; Less. syn. 

 p. 390 ; DC. prodr. 6. p. 294. 



Heads many-flowered, discoid ; the flowers all tubular; the marginal pis- 

 tillate, with a very slender somewhat 2-3-toothed corolla ; the others perfect, 

 with the corolla 4-5-toothed. Scales of the cylindrical involucre in a single 

 series, linear, acute, with a few calyculate bracteoles. Receptacle naked, 

 somewhat papillose. Branches of the style tipped with a pubescent cone. 

 Achenia oblong, striate, somewhat contracted at the apex. Pappus copious, 

 of very fine capillary bristles. — Erect annual herbs (the genuine species 

 American), with alternate simple leaves, and corymbose heads. Flowers 

 whitish or yellowish. 



VOL. II. — 55 



