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Description: Schweinitz's sunflower is a rhizomatous, perennial herb producing solitary stems, up to 1 to 2 m in height from a cluster of carrot-like tuberous roots. The stem branches only at or above mid-stem, with the branches departing from the stem at about a 45-degree angle. The stem is usually pubescent but can be nearly glabrous; it is often purple in color. Schweinitz's sunflower produces opposite leaves on the lower section of the stem, transitioning to alternate leaves above. The leaves are variable in shape, lanceolate, and typically wider near the base, typically larger in size near the base of the plant and gradually reduced upwards. Lower stem leaves are approximately 1.5 to 2.5 cm in width and approximately 10 to 20 cm in length and approximately 5 to 10 times as long as wide. The upper stem leaves below the inflorescence branches, are approximately 1 cm in width by 5 cm in length. All leaf margins are entire or may have a few obscure serrations and tend to be somewhat revolute. The leaf texture is somewhat thick and stiff. The upper leaf surface is rough to the touch with broad based spinose hairs pointing toward the tip of the leaf. The lower surface is more or less pubescent having soft white hairs, which obscures the leaf surface (USFWS 1992). Schweinitz's sunflower produces small yellow flower heads in September to October. The fruit is a glabrous nutlet 3.3 to 3.5 mm in length with rounded tips. "The following combination of characters separates H. schweinitzii from all other eastern North American species in the genus: heads small (the involucre less than 1 centimeter across), stems at least sparsely strigose or hirsute below the inflorescence, leaves sessile to short-petiolate (petiole less than 1.5 cm in length), very rarely to lanceolate, broadest near base, 5 to 10 times as long as wide" (USFWS 1992).
Habitat:
Schweinitz's sunflower inhabits clearings in, and edges of, upland oak-pine-hickory woods on moist to dryish clays, clay-loams, or sandy clay-loams that often have a high gravel content and are moderately podzolized. The underlying rock types are highly weatherable, generally contain low amounts of resistant minerals such as quartz, and generally weather to fine-textured soils. Requires the full to partial sun of an open habitat, which was formerly maintained over the species' range by wildfires and grazing by herds of bison and elk. Now most occurrences are confined to roadsides (USFWS 1992 and Weakley 2002). Schweinitz's sunflower habitat tends to be dominated by members of the Asteraceae, Fabaceae, and Poaceae families. This association emphases an affinity of the habitats to both longleaf pine-dominated sandhills and savannas of the southeastern coastal plain and to glades, barrens, and prairies of the Midwest and Plains.
Range:
Schweinitz's sunflower is endemic to the piedmont of North and South Carolina. There are 53 extant occurrences known, most of them along roadsides where they are difficult to protect. The species has lost much of its native habitat to forest succession due to the elimination of natural disturbances, and to conversion to pine plantations, and urbanization (NatureServe 2005). The North Carolina populations are located in Union, Stanly, Cabarrus, Mecklenburg, and Rowan Counties. The species has been extirpated from Stokes and Montgomery Counties in North Carolina. All the extant and historic sites for the species in South Carolina are in York County. Thirty-eight percent of the historically extant populations have been destroyed. Most of the remaining populations are small, with four of them containing less than 4O individuals each (USFWS 1992).
References
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