Silphium glutinosum, commonly known as sticky rosinweed, is a species of flowering plant in the family Asteraceae. It is endemic to Alabama in the southeastern United States, where it is restricted to dolomite glades in Bibb County.
Silphium glutinosum is a perennial herb arising from a short rhizome and typically growing tall. Stems are erect, green, and unbranched below the inflorescence.
Leaves are opposite, lanceolate to ovate, and sessile or with short winged petioles. Leaf margins may be entire or toothed. The stems, leaves, and phyllaries are pubescent and bear stalked, amber-colored glands, giving the plant a sticky, resinous texture.
The inflorescence consists of yellow flower heads arranged in open panicles, with individual plants producing between one and thirty heads. Each head contains both ray and disc florets, with 8âÂÂ16 ray florets per head. The fruit is an achene.
The species was first described in 2001 by James R. Allison based on material collected from Ketona dolomite outcrops in Bibb County, Alabama.
Silphium glutinosum is part of a group of narrowly endemic taxa associated with the Ketona dolomite glade system, a geologically and ecologically distinctive habitat in Bibb County, Alabama.
Silphium glutinosum is known only from Bibb County in west-central Alabama, where it occurs on Ketona dolomite outcrops and adjacent habitats.
It grows in glades and rocky outcrops, as well as along woodland margins and rocky stream edges, particularly near the Cahaba River. These habitats are characterized by calcareous substrates and support a number of endemic plant species.
Flowering occurs from June through September.
Silphium glutinosum is a narrow endemic with a highly restricted range in Bibb County, Alabama. It is ranked as G2 (globally imperiled) and S2 (imperiled within Alabama).
The species has a very limited range extent of less than 100 km<sup>2</sup> and is known from approximately 6âÂÂ20 occurrences, with around 12 extant populations documented.
Although it may be locally abundant at some sites, with populations of hundreds of individuals, its specialized habitat makes it vulnerable to disturbance. Threats include livestock grazing, trash disposal, and incompatible forestry practices.
Several populations occur on protected lands, including sites managed by The Nature Conservancy, which contributes to the species' relative short-term stability.