Perennial from very slender, nearly naked stolons, each ending in a turion from which the stem of the next year arises; stems slender, simple or branched, 1–5(–8) dm, canescently strigose-puberulent in the infl, but the middle and lower part usually more sparsely strigillose-puberulent, often in vertical strips; lvs all opposite, or the upper more often alternate, sessile or nearly so, sometimes with axillary fascicles, broadly linear to more often lanceolate or lance-linear, 2–7 cm × 2–15 mm, entire or nearly so, often revolute, not very hairy, the lower side commonly puberulent along the midrib but otherwise glabrous or nearly so, the upper side glabrous or with a few scattered hairs esp. along the midrib; infl usually nodding in bud, but soon erect; fls short-pedicellate in the upper axils, the pedicels elongating to 0.5–2.5 cm in fr; pet white to pink or lilac, 4–6 mm, evidently notched; 2n=36. Wet low ground; circumboreal, s. in Amer. to Pa., Wis., Colo., and Nev. July, Aug. (E. oliganthum)
A short herb. It may or may not have hairs and forms slender underground runners. It keeps growing from year to year. The stems are erect. The leaves are sword shaped and mostly opposite. They do not have teeth and do not have stalks. The flowers are pale pink or white. They are 8-12 mm across and in lax racemes.