Ambrosia L.

Herbs or undershrubs, glandular, aromatic. Leaves alternate or opposite, simple to pinnately or palmately lobed or dissected, petiolate or sessile. Inflorescence of distinct staminate and carpellate heads usually on the same plant. Staminate heads in terminal racemose or spicate clusters, sessile or stalked. Carpellate heads in sessile or stalked clusters in axils of leaves. Heads unisexual, staminate heads with involucral bracts laterally connate and saucer-shaped. Receptacle paleaceous. Male florets, few to many; corolla campanulate, hyaline, 5-lobed. Stamens 5, appendaged. Style short, truncate. Involucral bracts in female heads fused to form a hard, vase shaped conceptacle. Corolla and stamens absent. Styles exserted through spine-like beaks, elongate, spreading. Achenes tightly enclosed in the involucre.

Distributed primarily in N. America; ca 30 species, 1 in India.

Literature. PAYNE, W.W. 1964. A re-evaluation of the genus Ambrosia (Compositae). J. Arn. Arb. 45: 401-438.

List of Lower Taxa