Stellaria longifolia often is confused with forms of S. longipes but differs in having leaves that are widest at or above the middle and in having the angles of the stem and/or the leaf margins minutely papillate-scabrid. The capsules can be either straw colored or black. Plants with black capsules have been named var. atrata.

Hybrids with Stellaria borealis subsp. borealis often occur; see note under that species.