Flower:

Branching cluster at the top of the plant, with flowers single at branch tips. Flowers are ¼ to 3/8 inch across with 5 white petals that are deeply divided to look like 10. The 5 narrow star-like green sepals behind the petals are as long as or shorter than the petals and are 3-veined, the midvein more prominent then the lateral veins. 5 to 10 stamens surround the center; the stamen tips may be red, yellow or brown, changing color as the plant matures.

Flower stalks are up to 1¼ inches long, slender, mostly straight, smooth or sparsely soft-hairy. At the base of the stalk is a pair of small, papery bracts less than ¼ inch long.

Leaves and stems:

Leaves are opposite, very narrow, lance-linear to narrowly triangular, ½ to 1½ inches long and less than 1/8 inch wide, toothless, hairless, with a long taper to a pointed tip and may have a few hairs around the edge at the stalkless base. Leaves are widest at or near the base.

Stems are branched, slender, square, hairless on the upper plant but sometimes soft-hairy on the lower stem. Depending on conditions, plants may be erect and lanky or short and mat-forming, in either case spreading vegetatively from slender rhizomes.

Fruit:

Fruit is an oval to cone-shaped capsule up to ¼ inch long, usually blackish purple at maturity, rarely straw-colored. Inside are tiny brown round to kidney-shaped seeds.

Notes:

Long-stalk Starwort is a circumboreal species, found in alpine and northern latitudes of North America, Europe and Asia. While it commonly grows in a low, dense mat or clump, our encounter was with the taller, more spindly form. The growth habit, as well as variations in other characteristics such as leaf shape or hairiness, is (according to Flora of North America) apparently influenced by both genetics and environmental factors. Populations also tend to be sterile, perpetuating primarily by vegetative means. According to the DNR, it is currently known only from two Minnesota counties, in brush prairies, river banks and open woodlands, and was listed as a Special Concern species in 1984 due to its rarity.

The taller, more erect form is very similar to the common Long-leaf Starwort (Stellaria longifolia), which is typically more heavily branched with more flowers per branch, stems are hairless though rough along the angles, and leaves are typically widest at or above the middle, though this distinction may be subtle. The non-native Lesser Stitchwort (S. graminea) is also similar, but has proportionately broader leaves, is more heavily branched with more numerous flowers, and is a weed of dry roadsides, trail edges and other disturbed soils. There are two recognized subspecies of S. longipes: subsp. arenicola, limited to Lake Athabasca in northern Canada, has straw-colored capsules and is usually the tall, lanky form; subsp. longipes, present elsewhere, is more often the short, compact form with blackish purple capsules.