344 • COMPOSITE coreopsis 



BIDENS 



leaves usually all opposite, the lower bipinnately parted or divided, with 

 linear lobes ; the up,per trifoliolate, with entire linear leaflets, or the upper- 

 most linear and entire : heads numerous, in open cymes : bracts of the in- 

 volucre more or less scarious-margined, the outer lanceolate to subulate, 

 about a line long ; the inner broad-ovate and 3-4 lines long : rays 8-10 lines 

 long by half as broad, yellow with brown base, obtusely 3-lobed at the 

 summit; disk-flowers dark purplish-brown: achenes elliptical, distinctly 

 winged, crowned with 2 short subulate often deciduous teeth. Damp 

 meadows along rivers, Oregon to Brit. Columbia. 



45 BIDENS Tourn. L. Gen. n. 932. 



Annual or perennial herbs with opposite lower leaves and mostly 

 large heads of yellow flowers, Involucre campanulate or hemi- 

 spheric, its bracts in 2 series, distinct or united at base, the outer 

 often foliaceous and much larger than the inner. Rece'ptacle flat 

 or nearly so, chaffy, the chaff subtending the disk-flowers Rays 

 when present, neutral, mostly entire. Disk-flowers perfect, fertile, 

 with tubular 5-toothed corollas. Anthers entire or minutely 

 sagittate at base. Style-branches with short or subulate tips. 

 Achenes flat, quadrangular or nearly terete, cuneate, oblong or 

 linear. Pappus of 2-6 teeth or subulate barbed or hispid awns. 



B. frondosa L. Sp. 852. Glabrous or somewhat hairy annual : stems 

 erect, 2-8 feet high, branching: leaves pinnately 3-5-divided into lanceolate 

 or broader sharply serrate and pinnately veiny commonly petiolulate leaf- 

 lets, or the uppermost undivided: heads usually numerous, peduncled, 

 about 6 lines high: involucre campanulate becoming hemispheric, its 

 outer bracts more or lesr« foliaceous, often much exceeding the ovate-lance- 

 olate scarious-margined inner ones : rays none, or rudimentary and incon- 

 spicuous : achenes flat, oval or obovate, ciliate, with 2 slenderdownwardly 

 barbed awns. Moist places mostly along streams, o r egon to Brit. Colum- 

 bia and across the Continent. . 



B. cernua L. Sp. 832. Annual: stems glabrous or setulose-hispid, 1-3 

 feet high : leaves oblong-lanceolate, coarsely and irregularly sharply ser- 

 rate, 3-6 inches long, sessile and commonly somewhat connate-perfoliate 

 at base: heads numerous, 6-8 lines broad, nodding after or during flower- 

 ing : rays 6-12, 3-8 lines long, or more : involucre depressed-hemispheric. 

 its outer bracts commonlv ciliate, often large and foliaceous and much 

 exceeding the broad yellowish-margined membranaceous inner ones: 

 achenes flat, cuneiform, usually 4-awned the margins and awns retrorsely 

 barbed. In wet places, California to Brit. Colunbia and across the Con't. 



B. Beckii Torr. in Spreng. Neue Entdeck. ii, 135. Aquatic perennial; 

 submersed stems much elongated in deep water, simple or little branched: 

 submersed leaves sessile, 1-2 inches long, repeatedly divided into numer- 

 ous capillary segments ; emersed ones few, sessile, opposite or sometimes 

 in 3's, lanceolate or oblong, acute, serrate or laciniate, 6-18 lines long: 

 heads solitary or few, short-peduncled : involucre hemispheric, its bracts 

 oval or oblong, obtusish, glabrous, the outer somewhat shorter than the 

 inner: rays 6-10, obovate or oblong, obtuse, golden yellow: achenes nearly 

 terete, truncate at both ends, half- inch long: pappus of 3-6 rigid persistent 

 awns which are smooth below, the upper part downwardly barbed. In 

 ponds and slow flowing streames, Canada to New Jersey and Missouri: re- 

 ported from Green Lake King Co. Washington by Mr. C. V .Piper, perhaps 

 introduced. 



Subtribe v ) Madiex DC. Ray-flowers Ugulatc and fertile (rarely 



