46 LXX¥V. COMPOSITE. ‘BIDENs. 
10. C. rosea. Nutt. (Calliopsis. Spreng.) Rose-red Tickseed. 
St. branched; lvs. opposite, 1-veined, linear, entire; ped. short; outer 
scales very short; rays obscurely tridentate.—2 A very delicate species, in wet 
grounds, Mass. Dr. Robbins! to N.J. Stem slender, ereet, 8—16’ high. Leaves 
1—2’ long, scarcely 1” wide, clothing the stem. Heads few, small. Rays rose- 
color, Varying to white. Disk light yellow. Jl. Aug. 
46. BIDENS. 
Lat. bidens, two-toothed; the achenia have 2 (ormore) barbed teeth. 
Involucre nearly equal, double, scaly or leafy at the base; rays 
few, neutral; disk perfect ; receptacle chaffy, flat; pappus of 2—4 
awns, rough backwards ; achenia quadrangular.—_Lvs. opposite. Rays 
often wanting. 
* Rays inconspicuous or 0. 
1. B. pronpésa. Leafy Burr-Marigold. 
Fis. discoid ; outer invol. 6 times as long as the flower, its leaflets ciliate 
at base; lower lvs. pinnate, wpper ones ternate, lanceolate, serrate—@ A com- 
mon weed, in moist, cultivated fields throughout Can. and U.%., often called 
beggar ticks, from the 2-horned achenia which adhere to every one who passes 
by it. Stem 2f high, sending out many spreading branches. Lower leaves in 
3s or 5s. Flowers in clusters at the end of the branches, without rays, yellow, 
surrounded by a large and leafy involucre. Aug. Sept. 
2. B. connata. Willd. (B. tripartita. Bw.) Trifid Burr-Marigold. 
Smooth ; dvs. lanceolate, serrate, slightly connate at base, lower ones most- 
ly trifid; outer scales longer than the head, leafy; ach. with 3 awns.—@ In 
swamps and ditches, Can., N. Eng. to Mo. Stem 1—3f high, smooth and 4-fur- 
rowed, with opposite branches. Leaves opposite, smooth, serrate, the lower 
ones often divided into 3 segments, the rest generally entire, lanceolate, sharply 
serrate and somewhat connate. Flowers terminal, solitary, without rays, con- 
sisting only of the tubular, yellow florets, surrounded by aleafy involucre. Aug. 
\3. B. cernus. Water Burr-Marigold. } 
‘Fis. subradiate, cernuous ; owter invol. as long as the flower; dvs. lanceo- 
late, subconnate, dentate——In swamps and ditches, Can. to Penn. Stem 1—2f 
high, purplish, branched, round at base, striate above, branches opposite, leaves 
opposite, somewhat connated at base. Flowers yellowish-green, finally droop- 
ing, generally with yellow rays about 8 in number. Aug.—Oct. 
4. B. prpinnata. Spanish Needles. 
Smooth ; lvs. bipinnate; /fts. lanceolate, pinnatifid; Ads. subradiate ; outer 
invel. the length of the inner—(@ Grows in waste places, N. Y. Sartwell, Conn. 
Robbins. Stem 2—4f high, branching, smooth. Leaves bipinnately dissected, 
nearly smooth. Heads of flowers on long peduncles, each with 3—4 (or 0) ob- 
secure, obovate, yellow rays. Jl.—Sept. 
* * Rays conspicuous. 
5. B. cHRYSANTHEMOIDES. Radiate Burr-Marigold. ’ 
Fis. radiate ; rays 3 times as long as the nearly equal involucre; ls. ob- 
long, attenuate at each end, connate at base, dentate—@) A low plant, with 
Jarge, yellow-rayed flowers, in muddy places, Can. and U. 8. Stem 6—20’ 
high, round and smooth. Leaves smooth, with few remote teeth, narrow, oppo- 
site, with narrow, connate bases. Flowers commonly erect, rays about 8, large, 
spreading. Scarcely distinct from B. cernua. Sept. Oct. 
6. B. Becxn. Torr. Beck's Burr-Marigold. 
St. subsimple ; suhmersed lvs. capillaceous-multifid ; emersed ones lanceo- 
late, connate, acutely serrate or laciniate; fls. radiate; rays. longer than the 
involucre—2-In water, N. Y. Sartwell, &c. Vt. Chandler, N. to Can. Stem 
2—3f long, simple or with minute, slender branches above. Lower leaves dis- 
sected as in Ranunculus aquatilis ; wpper 1—2/ long, 4 as wide, deeply serrate. 
Head solitary, terminal, yellow. July. Aug. 
