Ageratina  

Shrubs or perennial herbs, usually erect. Leaves usually opposite; blade narrowly elliptic to deltate, mostly toothed, lobed, serrate, or crenate. Capitula laxly to densely corymbose. Phyllaries ca. 30, 2- or 3-seriate, distant to weakly subimbricate, mostly subequal; receptacle usually slightly convex, glabrous or with minute scattered hairs. Florets 10-60, often sweetly scented; corollas white or lavender, usually with slender basal tube and campanulate limb (in A. subg. Ageratina and A. subg. Klattiella), others narrowly funnelform; lobes distinctly longer than wide, outer surface smooth, glabrous or glandular, usually with hairs (in A. subg. Ageratina), inner surface densely papillose; antheropodium cylindric, usually elongate; anther appendage large, ovate-oblong, longer than wide; style base usually enlarged [except in A. subg. Apoda]; style branches rarely slightly broadened distally, densely papillose with projecting cells on lateral and outer surfaces. Achenes prismatic or fusiform, usually 5-ribbed, setuliferous or glandular or both; carpopodium distinct (cylindric in A. subg. Ageratina) [in others rounded or broadly stopper-shaped]; pappus setae uniseriate, 5-40, barbellate, often easily deciduous, capillary, often enlarged distally, often with outer series of shorter setulae. x = 17.