photo by Alan Cressler, obtained from Lady Bird Johnson Wildflower Center (wildflower.org), described as an unrestricted image (educational and scientific use)
Recently discovered in a far-northern Mississippi County, this extremely rare (S1, G1) sunflower species was previously known only in Georgia, Alabama, and Tennessee. Whorled sunflower is considered a narrow habitat specialist occurring in wet prairies and calcareous barrens.
From the USFWS Species Profile (ECOS Environmental Conservation Online System) Whorled sunflower is found in moist-soiled sites where little to no overstory canopy is present. Habitat quality ranges from remnant prairie or woodland sites to degraded sites along roadsides, railroad tracks, and agricultural fields. Despite their commonly degraded condition, associated plant species in these habitats indicates a community with strong prairie affinities
Distribution map from Biota of North America Program:
Photos by Darrell Brandon:
Description from Matthews, J.R., J.R. Allison, R.T. Ware, and C. Nordman. 2002. Helianthus verticillatus Small (Asteraceae) rediscovered and redescribed. Castenea 67 no. 1: 13-24.
Perennial from horizontal tuberous-thickened roots, with slender rhizomes up to 25 cm long. Stem slender, erect, 1-2 (rarely to 4+) m high, glaucous, pale green becoming reddish brown with age, unbranched below but with short axillary branches above, smooth and glabrous below, often sparsely strigillose medially, becoming strigillose-hispidulous in the infloresence. Leaves of the mid-stem mostly verticillate, 3s or 4s (-6), often opposite below and alternate or sometimes opposite in the inflorescence, linear-lanceolate, only the mid-vein prominent, narrowly acute to acuminate, gradually narrowed to a sessile base or a short petiole, 7.5-18.5 cm long, 0.7-2.0 cm wide, usually with a 10:1 ratio, entire or remotely toothed, ciliate proximally when young, revolute, firm in texture and brittle when dried, upper surface dark and slightly bluish-green, scabrous from pustular-based strigillose hairs, lower surface with sparse antrorse-strigose or ascending hairs, particularly at the base of the leaf and along the veins, paler than the upper surface and resin-dotted. Inflorescence of (1-) 3-7(-20) cymosely arranged heads, the branches closely ascending; involucre campanulate, 1 cm high and 1.5 cm wide, the bracts about 1 cm long, narrowly lanceolate, acuminate, strongly ciliate, the cilia becoming shorter distally, often medially sparsely strigillose, but mostly glabrous, slightly longer than the disk, very loose, spreading with only slightly reflexed tips; ray flowers mostly 13, (1-) 2 cm long, deep yellow (yellow tinged with orange); disk usually (1.0-) 1.5 cm broad, disk florets yellow, narrowly campanulate, 5-7 mm long, chaff oblanceolate or oblong, keeled, varying in a single head from short-acuminate to 2- or 3-cuspidate, papus of 2 broadly lanceolate, appressed-pubescent and lacerate awns, less than half the length of the disk corollas; achene 4-5 mm long, oblanceolate, light brown or mottled with dark brown speckles. Flowering late August-October.