Eupatorium altissimum L.

Tall Thoroughwort

Herb

Perennial

Vascular

Tall Thoroughwort is a native herbaceous perennial in the Sunflower family (Asteraceae). It occurs in central and north Alabama. Tall Thoroughwort grows in prairies, in cedar glades, and in dry, open woods. It is found exclusively on soils derived from limestone. Plants are 1-4 feet tall from a stout rhizome. The stems are pubescent and usually unbranched below the inflorescence. The leaves are opposite, sessile, lanceolate to elliptic in outline, with a few teeth towards the apex. The leaves have 3 main veins, are pubescent on both surfaces, and gland dotted. There are usually several pairs of smaller leaves in the axils of the main stem leaves, the nodes appearing leafy. Flowers are produced in heads. The heads are arranged in a terminal corymb. Each head has 6 white disc flowers. The fruit is an achene. Tall Thoroughwort in Alabama is an apomictic (forming fruit without sexual reproduction, the embryo develops from vegetative cells) polyploid (having three or more pairs of chromosomes per cell). Tall Thoroughwort is available from some wildflower nurseries. It prefers a dry, well-draining, clay soil in full sun. Tall Thoroughwort is drought tolerant and deer resistant.--A. Diamond

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Native

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