Long-leaf starwort is a perennial wildflower with spreading to ascending 4-angled stems up to 60 cm long. It is typically found growing amongst meadow grasses and thus, except for the flowers, difficult to see. The leaves are linear-lanceolate to linear in shape with acute tips. The bases of the leaves are sessile. Individual leaves measure from 1.5-3.5 cm long and are rarely more than 4 mm wide.
The inflorescence is a leafy-bracteate cyme of several to many white flowers. The slender flower pedicels range from 5-20 mm long. The sepals are 3-4 mm long and narrowly elliptic-lanceolate in shape with pointed tips. The 5 petals are about equal to or slightly exceed the sepals in length and each is deeply cleft so that the flower appears to have 10 narrow petals (See the photo above.).
Long-leaf starwort may be found in wet meadows, along grassy streambanks, in ditches, and on poorly drained soils.
Long-leaf starwort may be found from Alaska south to California and east to Newfoundland, New Mexico, and South Carolina.
In the Columbia River Gorge it may be found between the elevations of 800'-2000' between Cape Horn and the hilltops directly west of the Klickitat River.