Herbs, annual, from fibrous roots. Stems few or solitary, to 30(-40) cm tall, 4-angled, erect, often regularly divaricately branched, glabrous to scaberulous or hispidulous. Leaves and leaflike stipules at middle stem regions in whorls of 4-8, subsessile; blade drying papery, lanceolate, linear-lanceolate, or spatulate, (7-)12-25(-30) × (1.5-)2-5(-10) mm, glabrous to sparsely hispidulous on lamina and densely scaberulous to antrorsely aculeolate on veins and margins, base acute, apex obtuse to rounded; secondary veins not evident. Inflorescences terminal, capitate to subcapitate; peduncles 1.5-4 cm; involucral bracts leaflike, 1-12 mm, white ciliate at margins. Flowers sessile. Corolla pale to clear purplish blue, salverform, outside densely papillose; tube 8-10 mm, dilated in throat around anthers; lobes 4, elliptic to ovate, 2-3 mm, obtuse. Ovary ovoid, ca. 1 mm, glabrescent. Mericarps 1-1.8 mm, glabrous. Fl. Jun-Jul, fr. Aug-Sep.
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