Slender aquatic herbs, with linear entire verticillate leaves, and solitary (rarely 2-4) discoid peduncled terminal heads of small purplish flowers. Involucre broadly campanulate or hemispheric. Bracts imbricated in about 2 series. Receptacle conic, naked. Corolla regular, its tube short, its limb campanulate, 5-lobed. Anthers obtuse at the base. Style-branches slender, obtuse. Pappus of 5 broad cartilaginous obtuse scales. Achenes 5-angled. [Greek, hard scale, referring to the pappus.]

A monotypic genus of eastern North America.

1. Sclerolepis Uniflora (Walt.) Porter. Sclerolepis

Fig. 4151

Aethulia uniflora Walt. Fl. Car. 195. 1788. Sparganophorus verticillatus Michx. Fl. Bor. Am. 2: 98.

1803. Sclerolepis verticillata Cass. Dict. 48: 155. 1827. Sclerolepis uniflora Porter, Mem. Torr. Club 5: 311.

1894.

Perennial; stem simple, decumbent at the base, erect or ascending, glabrous or slightly pubescent, 1°-2° long, leafy. Leaves sessile, verticillate in 4's-6's, linear, 1-nerved, 4"-12" long, \"-\" wide, or the submerged ones filiform; head about 5" broad; bracts of the involucre linear-oblong, acutish, usually puberulent.

In shallow ponds and streams, New Hampshire to Florida. July-Sept.