CLASS XIX. ORDER I. 313 



A frequent and troublesome weed in corn fields, especially 

 where the soil is moist. Stem smooth, three or four feet high. 

 Lower leaves five-pinnate, sometinaes ternate, leafets lanceo- 

 late, serrate. Flowers terminal, erect, flosculous, surrounded 

 by a large, leafy involucrum or outer calyx. Florets small, 

 yellow. Seeds oblong, flat, tipt with two barbed awns, by 

 which they adhere lo the clothes, and to the coats of animals. — 

 August, September. — Annual. 



BiDENS TRIPARTITA. L. Trifid Burr Mart/gold. 



Flowers discoid ; outer calyx longer than the flower; 

 seeds with three awns ; leaves trifid. 



Stem two or three feet high, branching; leaves opposite, 

 mostly three parted with lanceolate, serrate segments; the lower 

 leaves frequently pinnatifid, the upper ones in the American 

 plant generally simple. Calyx short in comparison with the pre- 

 ceding. Seeds resembling those of the last with commonly a 

 third short awn between the other two. — Swamps and ditches. — 

 August. — Annual. 



BiDENS Crysanthemoides. Midi. Large Jlotvered Bidens. 

 Flowers erect, radiate: outer calyx waved, much 

 shorter than the raj;- ; leaves lanceolate, serrate, con- 

 nate. 



The large, golden flowers of this plant are very conspicuous in 

 wet situations in autumn. Its tops are usually eaten off" when 

 accessible to cattle, who appear fond of it. Stem erect, round, 

 smooth. Leaves glabrous, lanceolate, slightly toothed, tapering 

 at both ends, slightly connate at base. Flowers erect. Leaves 

 of the outer calyx oblong, obtuse, waved up and down on the 

 margin ; those of the inner calyx shorter, oval, acute. Ray very 

 large, spreading, yellow. Seeds with commonly four awns, in 

 which circumstance our plant seems to differ from that of Mi- 

 chaux. — September, October. — Annual. 



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