General: Annual herb from a short taproot and fibrous roots; stems erect or ascending, 5-30 cm tall, simple or branched at the base, glandular-hairy or smooth.
Leaves: Opposite, unstalked or the lowermost tapering to a stalk-like base, narrowly oblong to lanceolate, 0.5-3 cm long, irregularly toothed or entire, usually smooth.
Flowers: Inflorescence a terminal, bracted, elongate, lax raceme of several to many, very short-stalked (0.5-1.5 mm) flowers, the bracts alternate, gradually reduced upward; corollas whitish, inconspicuous, 2-3 mm across, irregularly 4-lobed; calyces short glandular-hairy or smooth, 3-6 mm long, deeply 4-lobed, the lobes lanceolate, unequal; styles very short, 0.1-0.4 mm long; stamens 2.
Fruits: Capsules, 3-4 mm long, flattened, heart-shaped, about as wide as long, broadly notched at the tip, glandular-hairy or smooth; seeds numerous, 0.4-1 mm long.
Notes: Two varieties occur in BC:
1. Plants smooth; rare on Vancouver Island and the lower Fraser Valley..................... var. peregrina
1. Plants short stalked-glandular in the inflorescences and on the capsules; the frequent variety....................... var. xalapensis (H.B.K.) St. John & Warren
Moist to wet roadsides, ditches, streambanks, vernal pools, meadows and clearings; frequent throughout S BC, rare northward (var. xalapensis), and rare (var. peregrina) on Vancouver Island and the lower Fraser Valley, where probably introduced from eastern N America; var. xalapensis - E to PQ and NS and S to NH, PA, FL, AL, AR, TX , NM, AZ, CA and MX.
