Veronica peregrina L. subsp. xalapensis (Kunth) Penn., purslane speedwell, necklace weed, neckweed. Annual, fibrous–rooted at soil–covered nodes, 1—several–stemmed at base, initially and often unbranched below inflorescence later with unexpanded axillary shoots, erect to ascending, in range 5—37 cm tall (aboveground); shoots with only cauline leaves on 3—5 nodes and leaflike bractlets at flowering nodes, with stalked glandular hairs in inflorescence, the hairs to 0.4 mm long.
Stems cylindric, to 3 mm diameter, green, internodes 15—20(—40) mm long, glandular–hairy.
Leaves opposite decussate (cauline leaves) and helically alternate leaflike bractlets, simple, petiolate to sessile with pair connected by low ledges across node then touching to fused at midpoint of stem node, without stipules; petiole flattish, to 5 mm long at the lowest node, indistinct from blade, mostly absent approaching inflorescence; blade oblanceolate–linear to oblanceolate or elliptic, 3—16 × 0.8—5.5 mm, dull, gradually tapered to rounded at base, low short–serrate on margins or subentire with minute teeth, rounded to obtuse at tip, midrib only conspicuous and raised slightly on lower surface, glabrous, lower surface sometimes with glandular hairs at base.
Inflorescence leafy raceme (panicle of several racemes), terminal, many–flowered, flowers often opposite at the lowest node and helically alternate above, not evenly spaced, bracteate, glandular–hairy; bractlet subtending pedicel leaflike, oblong–elliptic to oblong–oblanceolate, 5—6 × 1.5—2 mm increasing slightly in fruit, entire, rounded at tip, midrib inconspicuous, with glandular hairs below midblade; pedicel < 0.5 mm long.
Flower bisexual, radial, ca. 2.5 mm across; calyx 4–lobed, ± 2 mm long increasing 2× in fruit, glandular–hairy; tube cup–shaped, 0.5 mm long; lobes equal, oblong–oblanceolate, rounded at tip, veins obscure; corolla ± 2–lipped, 4–lobed, in range to 1.9 mm long, pale pinkish white without nectar lines; tube ca. 0.3 mm long; lobes spreading, equal, obovate, 1 mm wide, rounded at tip; stamens 2, fused to base of corolla tube; filaments ± 0.4 mm long, colorless; anther basifixed, dithecal, narrowly heart–shaped, 0.6 mm long, whitish, longitudinally dehiscent; pollen colorless; pistil 1, 1 mm long; ovary superior, compressed–ellipsoid and inconspicuously 2–lobed, green, lobes unequal, 2–chambered, each chamber with many ovules; style 0.1 mm long, whitish; stigma capitate, whitish, conspicuously papillate.
Fruit capsule, dehiscent by 2 valves along top, many–seeded, with 2 divergent, spreading lobes, compressed broadly heart–shaped, 3.6—4.1 × 4—5 mm, keeled, the notch < 0.5 mm deep, straw–colored to brown, not veiny, with several glandular hairs especially near keel and on lobes, not veiny on valves; style persistent in notch, 0.1—0.4 mm long; persistent calyx appearing as 2 deeply lobed lips appressed to the opposite, bulging sides of fruit.
Seed obovate, 0.7—0.9 × 0.5 mm, dull light caramel, flattened top–to–bottom with 1 face flat and the outer face ridged, rounded at tip, minutely sculptured.
A. C. Gibson & B. A. Prigge