The five white petals of stellaria longipes
are deeply divided, almost to the base, giving the appearance of ten petals. Beneath are five green sepals, around half as long - 0.15 inches. Sepals have a prominent midrib and three faint, lengthwise veins. Flowers are produced singly or in open clusters of up to 30, held on stalks of around one inch. Stamens number between five and ten, the styles usually three. Fruits are egg-shaped capsules, around 0.2 inches in length.
Stems are short, slender and square in cross-section. All plant parts are usually hairless, but the leaves, stems and sepals may have a covering of very short, fine hairs. Stems are green, sometimes tinged bluish. Leaves have a central vein, and sometimes a pair of fainter side veins. Leaf tips are pointed.
There are two subspecies: the usual ssp longipes
has dark purple capsules and variable leaf shapes, while ssp arenicola
(Canada only) has light brown capsules and narrowly lanceolate leaves.