386 COMPOSITiE. Coreopsis. 



2. Coreopsis rosea, Nutt. (Plate LXVII.) Small Rose-colored Coreopsis. 



Smooth ; stem leafy ; leaves opposite, narrowly linear, entire, obscurely 1 -nerved ; heads 

 on rather short peduncles ; scales of the exterior involucre much shorter than the interior ; 

 rays about 8 (rose-color), oblong, slightly 3-toothed ; achenia oblong, wingless, crowned with 

 an obscure truncate coroniform pappus. — Nutt. gen. 2. p. 179 ; Bigel.Jl. Bost. ed. 3. p. 338 ; 

 Bart. Jl. Am. Sept. 1. t. 12; Torr. compend. p. 312 ; Torr. ^ Gr. fl. N. Am. 2. p. 348. 

 Calliopsis rosea. Sprang, syst. 3. p. 611 ; Beck, hot. p. 205. 



Perennial. Stem about a foot high, slender, usually with a few erect branches. Leaves 

 1—2 inches long and scarcely a line wide, slightly ciliate at the connate base ; the axils 

 fasciculate. Heads few, (including the rays) about an inch in diameter. Peduncles 1-2 

 inches long. Disk yellowish. 



Sandy swamps, near Sag-Harbor, Long Island {Mr. S. B. Buckley). August. 



Div. 4. BiDENTiDE^E, Less., DC. Rai/s neutral, strap-shaped, or sometimes wanting. Achenia 

 obcompressed, or often tetragonal or terete and rostrate. Pappus of 2 - A (rarely 5-6) 

 retrorsely barbed or hispid awns. 



27. BIDENS. Linn. ; Endl. gen. 254:1. BUR-MARIGOLD. 



[ From the Latin, bidens, having two teeth ; in allusion to the two awns of the achenia.] 



Heads many-flowered ; the ray-flowers (3 - 8) neutral, often small or wanting ; those of the 

 disk tubular, perfect. Involucre double, often dissimilar ; the exterior frequently large and 

 foliaceous. Receptacle flattisli ; the chaff" deciduous with the fruit. Achenia obcompressed, 

 or slender and somewhat 4-sided, often attenuate or rostrate at the summit, crowned with 

 2-4 (rarely 5-6) downwardly barbed or hispid persistent awns. — Annual or sometimes 

 perennial weed-like herbs, with opposite, serrate, incised or divided leaves. Flow«rs mostly 

 yellow or yellowish. 



^ 1. PLATYCARP.a;A, DC. Achenia flat, oval or cuneiform, 7wt attenuated at the summit ; the 



margins usually ciliate or hispid. 



1. Bidens frondosa, Linn. Common Bur-marigold. Stick-tight. 



Lower leaves pinnately 5-parled, upper ones 3-parted ; the divisions lanceolate, tapering 

 at the base, serrate, the under surface and the petioles often a little hairy ; heads discoid, 

 pedicellate ; scales of the exterior involucre 2-6 times longer than the head, acutish, ciliate 

 towards the base ; achenia obovate-cuneiform, 2-awned, pubescent on the sides. — Linn. sp. 

 (ed. 2.) 2. p. 1166 ; Michx.Jl. 2. p. 136 ; Pursh, Jl. 2. p. 566 ; Ell. sk. 2. p. 431 ; Bigel. 

 Jl. Bost. p. 294 ; Beck, bat. p. 207 ; Hook.Jl. Bor.-Am. l.p. 314 ; Darlingt.Jl. Cest. p. 486 ; 

 DC. prodr. 5. p. 594 ; Torr. <$• Gr. Jl. N. Am. 2. p. 350. 



