Silphium confertifolium Small

Blackbelt Rosinweed

Herb

Perennial

Vascular

Blackbelt Rosinweed is a native herbaceous perennial in the Sunflower family (Asteraceae). It can be found in the northern 2/3’s of Alabama. Blackbelt Rosinweed is found on chalk prairies, on cedar glades, on marl outcrops, and on roadside banks. It often occurs in areas with thin soils derived from limestone. It is a perennial with a short rhizome. The stems are 1-3 feet in height, unbranched below the inflorescence, green in color, and glabrous. Leaves are basal and cauline. The basal leaves are large and present at flowering. Basal leaves are petiolate, elliptic to lanceolate in outline, entire, and glabrous except for cilia along the margins. Stem leaves are opposite, sessile, entire, glabrous, and quickly reduced in size upwards. Flowers are produced in heads. The heads are arranged in corymbs. The heads are small for the genus. Each head has 8-13 yellow ray flowers and 35–100 yellow disc flowers. The fruit is an achene. Blackbelt Rosinweed is sometimes treated as a variety of the widespread Starry Rosinweed (Silphium asteriscus Linnaeus var. latifolium (A. Gray) J. A. Clevinger). It differs from that species by its shorter stature, smaller head size, and persistent large basal leaves.--A. Diamond

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Native S3 (State Rank) G2 (Global Rank)

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