Plants to 2.5 dm; roots elongate, fleshily woody. Stems ± erect, simple or sometimes branching. Leaves sessile; blade terete, to 6 cm. Inflorescences cymose, much overtopping leaves; peduncle scapelike, to 15 cm. Flowers: sepals deciduous, ovate, 4 mm; petals pink to magenta, ovate to obovate, sometimes mucronulate, 6.5-8 mm; stamens 12-28; stigmas 3, spreading widely, linear, 1/2-1/3 as long as styles. Capsules subglobose, 4 mm. Seeds without arcuate ridges, 1.2 mm, corrugate-rugulose overall. 2n = 24. Flowering May-Aug. Sand or sandy soils, dunes, mounds, flats, banks, ridges, edges of igneous or metamorphic rock outcrops, along or near watercourses; 0-500 m; Ill., Ind., Iowa, Kans., La., Minn., Nebr., Tex., Wis. Within the overall area of its distribution, Phemeranthus rugospermus is nowhere abundant, its occurrence being everywhere spotty and localized. According to T. S. Cochrane (1993), the disjunctions probably reflect a history of long-distance dispersal from a center in the partially unglaciated Kansas and Nebraska sandhills, the present-day gaps resulting from a paucity of suitable habitats between that area and the others where it is now found. Even so, its discovery in Missouri, Arkansas, and/or Oklahoma would not be surprising.
From Flora of Indiana (1940) by Charles C. Deam
This plant was first reported by Babcock (Lens 1: 23. 1872) as found on the sand hills at Miller and Tolleston in Lake County. On Nov. 22, 1928, Norman C. Fassett wrote me that there were five specimens in the herbarium of the University of Wisconsin collected by L. M. Umbach at Miller on the following dates: July 26, 1895; June 23, 1898; June 27, 1899; July 17, 1906; and August 27, 1909. I have a specimen collected by Umbach on June 27, 1899. Holzinger says the species is perennial and grows in very sandy soil.