9. Veronica peregrina L. (neckweed, purslane speedwell)

V. peregrina var. xalapensis (Kunth) Pennell

V. peregrina ssp. xalapensis (Kunth) Pennell

Pl. 491 d–f; Map 2240

Plants annual, with fibrous roots or slender taproots. Stems 5–20(–30) cm long, erect to loosely ascending, sometimes from a spreading base (then usually not rooting at the lower nodes), glabrous to moderately pubescent with short, glandular hairs. Leaves mostly sessile, the lowermost leaves sometimes short-petiolate. Leaf blades 0.5–2.2 cm long, 1–4 times as long as wide, mostly relatively thick, narrowly oblong to oblong-oblanceolate, those of the petiolate leaves often lanceolate to ovate, broadest below to above the midpoint, mostly rounded or broadly and bluntly pointed at the tip, angled or short-tapered to rounded, or occasionally nearly truncate at the base, not clasping the stems, the margins unlobed, flat, entire or shallowly and irregularly scalloped or bluntly toothed, the surfaces glabrous or sparsely to moderately pubescent with short, glandular hairs. Inflorescences terminal, elongate, open, spikelike racemes, but (because the bracts are unreduced and the inflorescence frequently extends nearly to the stem base) appearing as flowers solitary in the leaf axils, with 6–20(–30) flowers, the axis visible between the flowers, the bracts 4–10 mm long, similar to the adjacent foliage leaves and only slightly reduced toward the axis tip, narrowly oblong to narrowly oblanceolate, the uppermost bracts sometimes linear. Flower stalks absent or to 1 mm long at flowering (to 1.5 mm at fruiting), shorter than the calyces, when present more or less ascending at flowering and fruiting. Calyces 3–6 mm long, the lobes subequal, deeply 4-lobed, the lobes narrowly elliptic to lanceolate, glabrous or glandular-hairy. Corollas 2.0–2.5 mm wide (2.5–3.0 mm long), white or occasionally pale yellow, lacking darker veins, the throat white or sometimes light greenish-tinged, the tube appearing relatively broad, wider than long, the lobes curved outward. Style 0.1–0.4 mm long at fruiting. Fruits 3–4 mm long, about as long as wide, heart-shaped in profile, flattened, the notch relatively broad and moderately deep (0.2–0.5 mm), the surfaces and/or margins glabrous or glandular-hairy, dehiscing along the sutures into 2 valves. Seeds numerous, 0.5–1.0 mm long, strongly flattened on both sides, but with a slender longitudinal ridge on one side, the surfaces appearing smooth or slightly pebbled, light brown to yellowish brown. 2n=52. April–August.

Scattered nearly throughout the state (nearly throughout the U.S. [including Alaska]; Canada, Mexico, Central America, South America, Caribbean Islands; introduced in Hawaii, Europe, Asia). Bottomland forests, margins of sinkhole ponds, banks of rivers, bases of bluffs, and disturbed marshes and fens; also crop fields, fallow fields, old fields, lawns, pastures, ditches, railroads, roadsides, and open, disturbed areas.

Most botanists have divided this species into two weakly distinct varieties. Typically, plants of var. peregrina are glabrous, whereas those of var. xalapensis have at least the stems and fruits glandular-hairy. However, especially the populations east of the Rocky Mountains appear to exhibit a great deal of variation in the abundance and distribution of the pubescence. Plants are encountered that are totally glabrous or with varying densities of pubescence occurring on only the stems or also on various combinations of the stems, leaves, inflorescence axes, calyces, and fruits. Even Pennell (1935) noted that intergradation between the two morphotypes was extensive during his early studies. In Missouri, glabrous plants are currently more common and have a broader distribution, whereas plants that are variously glandular-hairy are concentrated in counties bordering the Missouri and upper Mississippi Rivers. Comparing the overall North American ranges circumscribed by Pennell (1935) and Gleason and Cronquist (1991) it appears that the mostly western and southern var. xalapensis has been expanding its range into the eastern United States. It seems likely that the two varieties have come into broader contact in recent decades and the distinctions between them have become even more blurred. Thus, in the present work no attempt has been made to segregate infraspecific taxa.