Phytologia 19: 222. 1970.
Shrubs [trees], (30–)69–150(–200) cm. Stems erect (brittle), puberulent to glabrous. Leaves persistent, opposite; petioles 3–10(–15) mm; blades deltate to broadly ovate or somewhat hastate, (2–)3–5(–8) × 2–5 cm, bases truncate to cuneate, margins dentate, apices acute, faces glabrous or nearly so, eglandular. Heads clustered. Peduncles 2–14 mm, minutely puberulent. Involucres 4–6 mm. Phyllaries: apices acute, abaxial faces glabrous or nearly so. Corollas white to slightly pinkish, glabrous. Cypselae hispid. 2n = 34.
Phenology: Flowering mainly (Sep–)Oct–Nov(–Dec), also Apr–Jul.
Habitat: Bluffs, limestone outcrops and slopes, ledges along streams, often in oak-juniper woodlands
Elevation: 100–900 m
Tex., Mexico, West Indies (Cuba).
Ageratina havanensis apparently is the only species of the genus in the flora area with evergreen-persistent leaves.