COMPOSITiE. 18"5 



panicle; involucre scales in 2 rows, the onter linear spatulate; achenia broadly 

 •winged. 



Moist grounds; common. Aug., Sept.— Stem 4 to 8 feet high, slender, smooth be- 

 ~ow. AodlBmall, in a terminal IcafSy corymbose panicle ; rays 4 to 10 irregular, 

 oblanceolate, yellow; disk greenish-yellow. ItecpUiclc globular. 



34. BIDEXS, Linn, Burr Marigold. 



Lat. bidens, having two teeth ; in allusion to the two a'-rns of the achenia. 



Heads many-flowered, the ray-flowers 3 to 8 neutral, 

 often wanting; disk-flowers tubular, perfect. Involucre 

 double, unequal, the outer series often large and leafy. Re- 

 ceptacle iiattish, chaffy, the chaff deciduous with the fruit. 

 Achenia flattened, parallel with the scales of the involucre, 

 or slender and 4-sided, crowned with £ or more rigid and 

 persistent awns which are downwardly barbed. — Annual or 

 perennial herbs, with opposite various leaves, and mostly yellow 

 /lowers. 



* Says ineonspiciMis or none. 



1. B. frondosa, L. Common Beggar-ticks. 



Smooth or somewhat hairy; stem tall and branching; leaves 3 to 5-divided, tho 

 leaflets lanceolat?, pointed, coarsely toothed, •mostly petioled : outer leafy involucre 

 much longer than the head, ciliute below; rays none; achenia wedge-obovate, 

 2-awned, somewhat ciliate on the margin. 



Hi A t waste places ; common. July — Sept. A very troublesome weed 2 to 4 feet 

 high, sending out many spreading branches. Lower leaves pinnate, upper ones ter- 

 mite, lanceolate, serrate. Flowers in clusters at the ends of the branches, without 

 rays, yellow, surrounded by a large and leafy involucre. Achenia 2-awned, and as 

 in the ether species, adhering by their retrorsely barbed awns to the dress, and to 

 4 te fleece of animals. 



2. B. CONNATA, Muhl. Swamp Beggar-tides. 



Smooth; learns lanceolate, serrate, connate at the base; lower ones mostly trifid 

 scales of tin. outer involucre longer than the head, mostly obtuse, scarcely ciliate ; 

 rays none; achenia narrowly wedge-form, S-awned. 



Wet grounds; common. Aug. Annual. Stem 1 to -2 feet high, smooth and' 

 4-fi trowed, with opposite branches. Leaves tapering ink) margined petioles which 

 a e slightly united at the base; the lower often divided : the lateral divisions united 

 at the base and d.current on the petiole. 2- 7cw?\s terminal, solitary, without rays, 

 e .insisting only of the tubular yellow florets, surrounded by a leafy involucre. 



3. B. CERNUA, L. Nodding Burr-Marigold. 



Nearly smooth, low; leaves all undivided, lanceolate, unequally ferrate, scarcely 

 connate; heads discoid or radiate* nodding ; outer involucre longer than the head 

 achenia wedge-obovate, 4-awned, the margins downwardly barbed. 



Swamps and ditches. Annual. Aug. — Oct. Stem! to 2 feet high, purplish, stri- 

 ate above, branched around the base. Branches opposite. Leaves opposite, slightly 

 connate. Flowers yellowish-green, with or without rays. Kays when present, 

 about 8, smaller than B. chrysanth-cmoidts, the leaves irregularly toothed and the 

 outer involucre more leaf-like. 



4. B. bipinnata; L. Spanish Needles. 



Smooth, brandling; leaves petioled bipinnately parted, the segments lanceolate 

 or oblong ovate, mostly wedge-shaped at the base: heads on slender peduncles, with 



A2* 



