Not all botanists agree on the origin of this annual plant. Many believe it was introduced from Eurasia; others think it is native. Its stems may be erect (A,B,C) or sprawling. Lance-shaped stalkless or short-stalked leaves emerge from papery sheaths (ocrea) which have long, straight bristles on their margins (D). Stalks hold loosely arranged flowers originating either from the tips of branched stems (B,C) or the leaf axils (D). The tiny 1/8 inch flowers have 5, sometimes 4, tepals (petals and sepals that look alike). Tepals are white or greenish-white when open (F), but the outer portions of the budlike, unopened tepals may be tinged with pink (D,F). The outer surface of the tepals is also pitted with tiny glands (E) (a hand lens may be needed to see them).

The pitted outer surface of the flower buds separate this member of the Persicaria genus (Smartweeds) from all others except for P. punctatum (Dotted Smartweed). Separating these 2 can be a challenge and that magnifying lens you used to ID the pitted tepals will be helpful!  Only Water Pepper will have flower stalks arising from the under the sheath at the base of the leaf (axil).  Also, some Water Pepper plants may have flowers with 4 petals or pinkish unopened flower buds (tepals), helpful features when present. Water Pepper’s tiny seeds are also pitted and duller than the shiny black seeds of Dotted Smartweed.