Annual 0.5-3 dm, simple or branched especially below; main lvs oblong or linear-oblong to oblanceolate, 0.5-3 cm נ1-8 mm, irregularly toothed or entire; infl terminal, elongate, lax; bracts alternate, gradually reduced upwards, often not much different from the lvs, each subtending a single subsessile fl; cor white or whitish, only 2 mm wide; mature pedicels 1-2 mm; fr 3-4 mm, ±obcordate, the notch varying in depth; style very short, 0.1-0.3 mm; seeds numerous, 0.4-0.8 mm; 2n=52. Moist places; temperate N. and S. Amer., and intr. in Europe. Apr.-Sept. Our common form, the var. peregrina, is glabrous. The chiefly western var. xalapensis (Kunth) H. St. John, has the stem and commonly also the sep and frs ±pubescent with short, gland-tipped hairs; it reaches the w. edge of our range, and extends e. to the Atlantic along our n. border.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual native herb; stems simple or branched, erect, ascending, 15-30 cm tall; herbage glandular and pubescent, leaves and bracts often glabrous or the plant wholly glabrous; short taproot. Leaves: Pessile or the lowermost leaves narrowed to a petiolar base, blades 0.5-2.2 mm long, 0.5-5 mm wide, narrowly oblong to oblanceolate, entire or irregular, crenate-serrate. Flowers: Raceme terminal, elongate, glandular-puberulent, bracts foliaceous at the base, gradually reduced upwards, corolla inconspicuous, whitish. Fruits: Capsules 3-4 mm long and slightly wider, obcordate with a broad notch at the top; numerous seeds. Ecology: Usually along streams and washes to 10,000 ft (3050 m); flowers March-September. Distribution: Introduced to N. Amer., in every state in the U.S.; south to S. Amer.; also in Asia, Europe and Australia. Notes: Differs from other species by the terminal raceme, annual habit, fibrous roots or taproot, short pedicels, and whitish corolla. Ethnobotany: Navajo use plant as ceremonial emetic. Chewed plant is blown toward deer for good luck while hunting. Etymology: Veronica is named for Saint Veronica, while peregrina is foreign or exotic, wandering or straggling in growth. Synonyms: None Editor: SBuckley 2010, FSCoburn 2015
From Flora of Indiana (1940) by Charles C. Deam
This is a common and obnoxious weed in cultivated grounds throughout the state except the northern counties where it is rare. When once it becomes well established in gardens, it is difficult to eradicate or to keep in control. [Deam calls plants with glandular-pubescent stems var. xalapensis]. This is a variety rare to infrequent in all parts of the state except in the sandy areas where it is more frequent but I have never seen it entirely displace the species.
Indiana Coefficient of Conservatism: C = null, non-native
Wetland Indicator Status: N/A
Diagnostic Traits: stems and leaves usually glabrous, leaves mostly entire or obscurely toothed; flowers in axils of bracts much smaller than lower foliage leaves; pedicels up to 1 mm.