False Fennel

Perennials, 50–200 cm. Stems (from short caudices) single, branched distally, glabrous throughout, gland-dotted. Leaves opposite (proximal) or alternate (nodes often appearing leafy by development of leaves on lateral buds without axis elongation); petiolate or sessile; blades (usually pinnately or ternately lobed) or lobes 1-nerved or pinnately nerved, linear, 20–100 × 0.2–0.5(–1) mm, bases slightly expanded, margins entire, apices rounded to acute, faces sparsely puberulent to glabrate, gland-dotted. Heads in paniculiform arrays (branches supporting heads recurved, secund). Phyllaries 6–10 in 1–2 series, lanceolate, 1.5–3 × 0.5–0.7 mm, apices acuminate, mucronate, abaxial faces glabrous or glabrate (not gland-dotted). Florets 5; corollas 2–2.5 mm. Cypselae 1–1.5 mm; pappi of 15–30 bristles 2–2.5 mm. 2n = 20.

Eupatorium capillifolium (Lamarck) Small var. leptophyllum (de Candolle) H. E. Ahles

Eupatorium leptophyllum, commonly called false fennel, is a herbaceous perennial plant in the family Asteraceae native to the southeastern United States from Mississippi to the Carolinas. Like other members of the genus Eupatorium, it is about one to two meters (40-80 inches) tall and has inflorescences containing a large number of tiny white flower heads, each with 5 disc florets but no ray florets. E. leptophyllum grows in wet areas and can grow in shallow water, often at the edges of ponds.