344 OOMPOSlTiE coreopsis 



I I DENS 



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

 linear lobes ; the upper trifoliolate, witli entire linear leaflets, or the upper- 

 moat 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 2-4 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. In damp 

 meabows 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. Receptacle flat 

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

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

 with tubular 5-tbothed 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. Pp. 852. Glabrous or somewhat hairy annual: stems 

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

 or broader sharply serrdte 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 less foliaceous, often much exceeding the ovate-lance- 

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

 spicucus : achenes flar, OYal or obovate, ciliate, with 2 slender downwardly 

 barbed awns. Moist places mostly along streams, Oiegon to Brit. Colum- 

 bia and across the Continent. 



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

 feet high : leaves oblong-lanceolate, coarsely and irregulBrly 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 commonly ciliate, often large and foliaceous and much ex- 

 ceeding the broad yellowish-margined membranaceous inner ones: achenes 

 flat, cuneiform, usually 4-awned, the margins aud awns retrorsely barbed. 

 In wet places, California to Brit. Columbia and across the Continent. 



B. Beckii Torr. in Spreng. Neue Entdeci. 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*8, lanceolate or oblong, acute, serrate or laciniate, 6-18 lines long; 

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

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

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

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

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

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

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

 introduced. 



Subtribe v, Madieas DC. Ray-flowers ligulate and fertile, (rarely 



