204. Flaveria Jussieu, Gen. Pl. 186. 1789.
黄顶菊属 huang ding ju shu
Annuals, perennials, or subshrubs. Stems erect or decumbent, branched. Leaves cauline, opposite, petiolate or sessile; blade oblong-ovate to lanceolate or linear, both surfaces glabrous or shortly pubescent, margin entire or serrate, or spinulose-serrate. Synflorescences of lax or dense aggregations of capitula in corymbose panicles or glomerules. Capitula radiate or discoid; involucres oblong, urceolate, cylindric, or turbinate, 0.5-2 mm in diam.; phyllaries persistent, 2-6(-9), 1-seriate; receptacle small, convex, epaleate. Ray florets 0 or 1(or 2), female, fertile, when present external to clusters of capitula; corollas yellow or whitish. Disk florets 1-15, bisexual, fertile; corollas yellow, tubes shorter than to ± equaling funnelform to campanulate throats, lobes 5, ± deltate. Achenes black, weakly compressed, narrowly oblanceolate or linear-oblong, ribbed, glabrous; pappus usually absent, or sometimes persistent, of 2-4 hyaline scales, or coroniform, or of connate scales. x = 18.
About 21 species: India, Mexico, United States; Africa, Australia, Caribbean, Central and South America; one species (introduced) in China.
See the revision of Flaveria by Powell (Ann. Missouri Bot. Gard. 65: 590-636. 1978).