Verbena rigida Spreng., veiny vervain. Perennial herb, 1—several–stemmed at base, suberect, in range to 30 cm tall; shoots with only cauline leaves, short–hirsute and with stalked glandular hairs.
Stems 4–sided, to 4 mm diameter, green to purple–red, edges rounded, hairs angled downward.
Leaves opposite decussate, simple, sessile, without stipules; blade oblanceolate (lower leaves) to low–serrate and inrolled (revolute) on margins (upper leaves), pinnately veined with veins sunken on upper surface and raised on lower surface, short–hirsute.
Inflorescence spike, terminal, many–flowered, flowers in whorls of 3, conspicuously bracteate, evenly short–hirsute and with stalked glandular hairs; rachis hidden by flowers and bractlets, with short internodes; bracteate subtending flower leaflike, ovate to triangular, 14—15 mm long, ≤ bractlet, green, revolute on margins with serrate teeth inrolled, appearing acuminate at tip (revolute), short–hirsute and with stalked glandular hairs.
Flower bisexual, bilateral, ± 13 mm across; calyx 2–lipped, 7—9 mm long, short–hirsute with stalked glandular hairs; tube cup–shaped, with sinuses of lips at ± midpoint, sinuses unequal and deeper on lower side, white at base to greenish above; lips 2–lobed, green, lobes ± deltate, 1.5—2 mm long, with inrolled (revolute) margins at tip, short–hairy and with glandular hairs on inner surface; corolla 2–lipped, 14—15 mm long, white; tube + throat bell–shaped, 5—5.5 × 2—2.5 mm, tube portion glabrous, throat with stalked glandular hairs on outer surface; lips with stalked glandular–hairy; upper lip hoodlike, 3—3.5 mm across, blushed lavender, with some hairs on inner surface; lower lip conspicuously 3–lobed, lateral lobes obovate, to 7 mm long, central lobe with floor with 2 upward pleats, semicircular and cupped ± 3 × 3 mm; stamens 4 in 2 pairs, one pair longer than other pair and anthers stacked, attached to corolla throat before sinuses; filaments strongly flattened, 6.5—8.5 × 1—1.2 mm, white but greenish at top, barbed on margins; anthers dorsifixed, dithecal, pale yellow with light purple hairs on inward–facing side, longitudinally dehiscent but almost porelike on end with hairs; pollen pale yellow; nectary covering lower portion of ovary; pistil 1, 13—14 mm long; ovary superior, compressed side–to–side, ca. 2 × 2 × 1 mm, green, villous, 2–chambered, each chamber with 1 ovule; style in hood and curved downward toward the top anthers, white at base to green approaching dark green stigma, stigma at level of upper anthers, triangular with a sterile and fertile lobe.
Fruit not observed in range; schizocarp (microbasarium), of 4 dry, 1–seeded mericarps (nutlets).
A. C. Gibson