ORDER 70. COMPOSITE. 453 



branching plant, I to 2f high, with a panicle of large, showy, yellow heads. Lvs. 

 mostly opposite, thin, the upper 3-cleft, subsessile. Ach. ' long, awns half as 

 long. JL, Aug. 



21 C. discoidea Torr. & Gr. Glabrous, much branched, erect ; Ivs. ternate, Jong- 

 petiolate ; Ifts. ovate-lanceolate, strongly dentate, hds. discoid on slender pedun- 

 cles; outer involucre 3 5 linear-spatulate, leaf-like bracts; ach. linear-oblong, 

 twice longer than the 2 erect awns which are hispid upwards. (T 1 Ohio to La. 

 Stem and branches purplish. Terminal leaflets 3 5 by !', lateral much 

 smaller. Heads small (3" diam.), about 30-flowered. Jl. Sept. 



58. BIDDEN S, L. BURR-MARIGOLD, (Lat bidens, two-toothed ; the 

 schema have two (or more) barbed teeth.) Involucre double ; scales 

 somewhat similar, or the outer foliaceous; rays 4 to 8 (sometimes 

 none), neutral ; disk-flowers perfect ; receptacle chaffy, flat ; pappus of 

 2 to 4 awns rough backwards; achcnia obcompressed, obscurely quad- 

 rangular. Lvs. opposite, incised. Fis. yellow. 



^ Achcnia linear, somewhat 4-angled, 3 to 4-awncd. Eays few or none No. 1 



Achenia flattened, broadest at top, Eays none or very few Nos. 24 



Eays about 8, showy, regular Nos. 5, 6 



1 B. bipinnata L. SPANISH NEEDLES. Smooth, Ivs. bipinnate, Ifts. lanceo- 

 late, pinnatifid, rays very short or none; outer in vol. the length of the inner; 

 ach. slender, elongated. (I) Grows ia waste places Conn,, N. Y., west to I1L 

 St 2 to 4f high, branching, smooth, Lvs. bipinnately dissected, nearly smooth, 

 lids, of flowers on long peduncles, each with 3 or 4 (or none) obscure, obovate, 

 yellow rays. Jl. Sept. 



2 B. frondosa L. Hds. discoid; outer invoL 6 times as long as the flower, 

 Us leaflets ciliate at base; lower Ivs, pinnate, upper ones ternate, lanceolate, ser- 

 rate; ach,. 2-awned. A common weed, in moist, cultivated fields throughout 

 Can, and U, &, often called Beggar-ticks from the 2-horned achenia which adhere 

 to every passer-by. St. 2f higli, diffusely branched. Lower Ivs. in 2s or 5s. 

 Pis. in clusters at the end of the branches, without rays, yellow, leafy. Aug., 

 Sept 



3 B. connata "Willd, Hds. discoid, smooth; Ivs. lanceolate, serrate, slightly 

 connate at base, lower ones mostly trifid; outer scaks longer than Hie head, leafy ; 

 cch. with 3 awns. (T) In swamps and ditches, Can. N. Eng., to Mo. St 1 to 3f 

 high, smooth and 4-furrowed, with opposite branches. Lvs. thin, taper-pointed, 

 often all undivided. Hds. scarcely ever with a ray, Aug. (B. tripartita, Bw.) 



4 B. cerrma L. Hds. subradiate, cermwus; outer invol. as long as the flower ; Ivs. 

 all simple, lanceolate, subconnate, dentate. In swamps and ditches, Can. to Pa. 

 and Wise. St 1 to 2f liigh, purplish, branched, round at base, striate above. 

 Branches opposite. Lvs. opposite, somewhat connate at base. Fls. yellowish 

 green, finally drooping, generally with small yellow rays about 8 in number. 

 Aug., Oct. 



5 B. chrysanthemoides L. Rays 3 times as long as the nearly equal invol. ; 

 Ivs. oblong, attenuate at each end, connate at base, dentate. (I) A low plant, with 

 large, yellow-rayed flowers, in muddy places, Can. and U. S. ' Stem 6 20' high, 

 round and smooth. Leaves smooth, with few remote teeth, narrow, opposite, 

 vrith narrow, connate bases. Flowers commonly erect, rays about 8, large, 

 spreading. Scarcely distinct from B. cernua. Sept., Oct 



6 B. Beckii Torr. St subsimple; submersed Ivs. capillaceous-multifid ; emersed 

 ones lanceolate, connate, acutely serrate or lanciniate; fls. radiate; rays longer 

 than the involucre. 4 In water, K Y. (Sartwell), Ac. Vt. (Chandler), N. to 

 Can. Stem 2 3f long, simple or with minute, slender branches above. Lower 

 leaves dissected as in Ranunculus aquatilis ; upper 1 2' long, | as wide, deeply 

 serrate. Head solitary, terminal, yellow. July, Aug. 



59. ACMELXA, L. (Gr. a,K\ir\, a point; from the sharp taste of 

 the foliage !) Heads radiate ; involucre shorter than the disk, double, 

 appressed, pubescent; receptacle, conical, chaffy ; pales embracing the 

 flowers; rays about 12, ?, disk $ ; achenia compressed, those of the 



