864 LXV. C0MP0SITJ3. [Cosmos. 



1. C. bipinnatus (twice-pinnate), Cav.- Ic. 1. 14. Leaves divided into narrow 

 linear, almost filiform lobes. Heads very showy, the rays often more than Im. 

 long. Achenes smooth with abrupt beak ; awns 1 to 8, very short or wanting. 



Hab.: Often met with as a stray from gardens. 



62. BIDENS, Linn. 



(The achenes having two or more teeth-like bristles.) 



Involucral bracts few, in about 2 or 3 rows, the outer ones herbaceous, the 

 inner ones usually bordered with a thin whitish margin. Eeceptacle chaffy. 

 Eay-florets neuter, sterile, ligulate or sometimes wanting ; disk-florets tubular, 

 hermaphrodite, 5-toothed. Anther.=i obtuse at the base. Style-branches with an 

 acute or subulate' point. Achenes broad and flattened or slender and 4-angled, 

 often produced into a short beak. Pappus of 2 to 4 rigid retrorsely hispid 

 persistent awns. — Herbs with opposite leaves. Flower-heads or terminal 

 peduncles, the ray yellow or white. 



Of the 2 sections of the genus, one, Platycarpaia, belongs chiefly to the temperate regions of 

 the northern hemisphere, the Australian species being identical with one of the common northern 

 ones ; the other, Fdlocaj-pcea, is entirely American with the exception of the 2 Australian 

 species, which are common weeds in all warm countries. — Benth. 



Section I. Platycarpeeai — Achenes flat and rather broad. 



Leaves divided into 3 lanceolate serrate segments . 1. B. tripartita. 



Section II. Psilocarpaea. — Achenes slender, i-angkd. 



Leaves mostly pinnate, with 3 or 5 segments. Eay white 2.7?. pilosa. 



Leaves mostly bipinnate; Eay yellow B. B. bipinnata. 



1. B. tripartita (leaves 8-partite), Linn.; DC. Prod. v. 594 ; Benth. Fl. 

 Austr. iii. 548. A rather stout erect glabrous annual 1 to 2ft. high. Leaves 

 deeply cut into 3 lanceolate serrate segments. Flower-heads on terminal 

 peduncles, erect or somewhat drooping. Involucre hemispherical, J to lin. 

 diameter, the outer bracts, sometimes nearly lin. long, leaf-like and spreading, 

 the inner ones short, broad, often shining and yellow on their edge. Florets 

 either all tubular without any ray or with a few outer ligulate yellow florets. 

 Achenes flat, crowned by 2 or 3, very rarely 4 awns. — B. repens, Don.; DC. Prod. 

 V. 595. 



Hab.: Southern localities. 



The species is widely spread over the temperate regions of the northern hemisphere.— BcntA. 



2. B. pilosa (pilose), Linn. ; DC. Prod. v. 597 ; Benth. Fl. Austr. 543. An 

 erect glabrous or slightly hairy annual, 1 to 2ft. high. Branches angular. Leaves 

 thin, pinnately divided, or the lower ones sometimes simple ; segments 3 or 

 sometimes 5, petiolulate, ovate or ovate-lanceolate, 1 to 2in. long, serrate or 

 rarely lobed. Flower-heads few, terminal, rather small, on slender peduncles. 

 Involucral bracts 2 to 8 lines long. Ray-florets white, few and short or some- 

 times wholly wanting. Achenes slender, 4-angled, the inner ones often 6 to 7 

 lines long, the outer ones shorter. — Benth. Fl. Hongk. 183, with the synonyms 

 adduced. 



Hab.: Brisbane Eiver, Moreton Bay, F. v. Mueller. A very common weed, 



The species is very common as a weed over most warm countries both in the New and the 

 Old World. 



