Ageratina aromatica (L.) Spach

Intergrades (probable hybrids) between Ageratina aromatica and A. altissima were identified by A. F. Clewell and J. W. Wooten (1971) over a broad area of their sympatry. They also found intergrades between A. aromatica and A. jucunda where their ranges meet.

Perennials, 30–80(–100) cm. Stems erect, villous-puberulent. Leaves opposite; petioles 1–8(–12) mm; blades narrowly to broadly deltate to nearly ovate or lanceolate, 2–7(–9) × 1.5–4 cm, (usually subcoriaceous) bases rounded or truncate to barely cuneate or subcordate, margins usually crenate, sometimes crenate-serrate to dentate or subentire, apices acute to obtuse, faces minutely pilose. Heads clustered. Peduncles 2–9 mm, densely and closely puberulent. Involucres 3.5–5 mm. Phyllaries: apices acute, abaxial faces puberulent to villous-puberulent. Corollas white, lobes sparsely villous. Cypselae usually glabrous or sparsely puberulent (near apices), rarely hirtellous on angles. 2n = 34.

Eupatorium aromaticum Linnaeus, Sp. Pl. 2: 839. 1753; E. latidens Small

Ageratina aromatica, also known as lesser snakeroot and small-leaved white snakeroot, is a North American species of plants in the family Asteraceae. It is widespread and common across much of the eastern and southern United States from Louisiana to Massachusetts, as far inland as Kentucky and Ohio.