General: Perennial herb from a creeping rhizome; stems prostrate or ascending to erect, several, branched, round, smooth or sometimes short spreading-hairy below, 30-120 cm tall/long.
Leaves: Basal leaves few, soon deciduous; stem leaves in whorls of 6-8, sometimes 4 on the smaller branches, linear to oblanceolate, 1-3 cm long, 1-veined, short stiff-hairy on the margins, unstalked.
Flowers: Inflorescence loose terminal clusters of many stalked flowers on branchlets in most upper axils; corollas saucer-shaped, whitish, 2-4 mm wide, 4-lobed; calyces obsolete.
If more than one illustration is
available for a species (e.g., separate illustrations were provided for two
subspecies) then links to the separate images will be provided below.
Note that individual subspecies or varietal illustrations are not always available.
