Eupatorium album L.

White Thoroughwort

Herb

Perennial

Vascular

White Thoroughwort is a native herbaceous perennial in the Sunflower family (Asteraceae). It occurs throughout Alabama in dry pine or mixed pine-hardwood forests, in sand hills, and on roadside banks. It is a perennial with a caudex (the slightly enlarged hardened basal portion of the stem from which new growth emerges) or short rhizome. The roots are thick and cord-like. The stems are usually unbranched below the inflorescence, green in color, and pubescent. Leaves are opposite, sessile, elliptic to lanceolate in outline, with serrate margins. The leaves are pubescent and gland dotted, and often folded. Flowers are produced in heads. The heads are arranged in corymbiform arrays. The phyllaries are long acuminate or attenuate, pubescent, and gland dotted. The apices and margins of the phyllaries are white. Each head has 5 white disc flowers. The fruit is an achene. Two varieties occur in Alabama. Eupatorium album Linnaeus var. album occurs throughout the state. It has smaller leaves that are pubescent and have obtuse to rounded apices. Eupatorium album Linnaeus var. vaseyi (Porter) Cronquist is found in northern Alabama. It has larger leaves that are pubescent or glabrous and have acute apices. Molecular data suggest that this variety arose through hybridization between var. album and Eupatorium sessilifolium. White Thoroughwort is available from some wildflower nurseries. It prefers a well-draining sandy soil in full sun.--A. Diamond

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Native G5T5 (Global Rank)

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