COMPOSIT.E. (cOilPOSlTE FAMILY.) 2G1 



42. BIDENS, L. BrR-MAUiGOLD. 



Ilotitls manj-'flowcrcd ; the rays wlicn present 3-8, neutral. Involucre (lonl)Ie, 

 the outer commonly large and foliaccous. IJcccptaclc flattish ; the cliall' decidu- 

 ous with tiic fruit. Achenia flattened parallel with the scales of the involucre, 

 or slender and 4-sided, crowned with 2 or more rigid and persistent awns which 

 arc downwardly barbed. — Annual or perennial licrbs, with opposite various 

 leaves, and mostly yellow flowers. (Latin, bidens, two-toothed.) 



* Achenia flat, not tapering at the summit. {All annuals ?) 



1. B. frondbsa, L. (Common Beggar-ticks.) Smooth or rather hairy, 

 tall (^o-G" high) and branching; leaves 3-^<licid('d ; the leaflets mosllj stal/ced, 

 lanceolate, pointed, coarsely toothed ; outer leafy involucre much longer than 

 the head, ciliatc below ; rays none or few and very small ; achenia tvedye-oliovate, 

 2-awned, the vtan/ins ciliate with upwardlij-tnnied bristles, except near the summit. 

 — Moist waste places : a coarse troublesome weed, the achenia, as in the other 

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

 of animals. July - Oct. 



2. B. COnnita, Muhl. (Swamp Bicggar-ticks.) Smooth (l°-2° high) ; 

 leaces lanceoiite or oblong-lanceolate, jiointcd, sharply serrate, tapering into mar- 

 gined piitioles which are slightly united at the base ; the tower oflen 3-dirided, their 

 lateral divisions united at tlf. base and decnrrent on the petiole ; scales of the outer 

 involucre longer than the head, few, mostly obtuse; raj/s none; achenia narrowli/ 

 wed(je.-form, 3- (2-4-) awiwd, the mnnjiits minntelij retrors'ly ciliate. (B. tripartita, 

 Bigel.) — A thin-leaved more jjetioled form is B. petiolata, Nutt. — E. 2\'ew Eng- 

 land to Illinois, and southward. — V'ar. comosa is stouter, the leaves commonly 

 all simple, upper ones nearly sessile, the heads larger and with more numerous 

 and leafy bracts. — Illinois, Kentucky, and westward. Aug. -Oct. 



3. B. c6rnua, L. (Smaller Bur-Marigold.) Nearly smooth (5'- 10' 

 high); leaves (dl undivided, lancobite, uneqwdti/ serrate, scarcely connate; heads 

 nodding, otV/i or without (light yellow) rays: outer involucre longer than the 

 head; achenia wedgc-obovate, 4-awned, the margins downwardly barbed. — 

 Wet places, Virginia to Wisconsin, and northward. Julv - Scj)t. — Kavs, when 

 present, smaller than in the next, the leaves irregularly toothed, and the outer 

 involucre more leaf-like. (En.) 



4. B. Chrysanthemoidas, Michx. (Larger Bur-Marigold.) Smooth, 

 erect, or reclining at the i)as;; ((-,'-30' high) ; leaves lanceolate, tapering at both 

 ends, more or less connate, regularly serrate: outer involucre mostly sliorter than 

 the sho'vy ,/o!den-yello,v {V long) rays; achenia wedge-sliai>ed. with almost prickly 

 downwardly barbed m irgins ; awns 2,3, or 4. — Swamps : common. Aug. - 

 Oct. — Northward it runs into No. 3. 



* * Arhenin linear or airl-shaped, A-sided, slender, tapering at the summit. 



5. B. B6Gkii, ToiT. (Watkr Marigold.) .Ir/w///-. perhaps perennial, 

 smooth ; stems long and slender, bearinu: crowded immersed lemv.s mnn>/ times dis- 

 sected into flne capillary divisions ; the few emerging leaves lanceolate, slightly 

 connate, toothed ; heads single, short-jiedimelcfl ; involucre much shorter than the 

 shou-y {gofden yellow) rays: achenia linear, thickish, .smooth (V Icmg), be:irin<r 4- 

 6 stout divergent awns which are an inch long and barbed only towards the 



