Bidens

Tutin, T.G., Heywood, V.H., Burges, N.A., Moore, D.M., Valentine, D.H., Walters, S.M. & Webb, D.A. 1976: Flora Europaea 4
but modified
1Pinnae unlobed; achenes about equalling the inner involucral bracts, rarely longer
1'Pinnae lobed almost to the midrib; achenes longer than the inner involucral bracts
2Leaf-lobes rhombic to broadly lanceolate; pappus-bristles 2-4 mm long, erecto-patent at maturity; outer achenes 8-10 mm long
2'Leaf-lobes mostly linear-lanceolate; pappus-bristles 1-2.5 mm long, erect at maturity; outer achenes 6-8 mm long