Verbena canescens Kunth, gray vervain. Perennial herb, not rosetted, 1—several–stemmed at base, with ascending flowering branches in canopy, ascending or suberect to spreading, in range < 28 cm tall; shoots with only cauline leaves, appearing grayish, with hirsute hairs having blisterlike bases (pustulate).
Stems 6–ridged, somewhat 4–sided, < 2 mm diameter, tough, with a pair of ledges between leaves, on internode the 2 faces descending from midrib convex having a fine central ridge and bounded by a ridge on each edge, the 2 faces descending from ledges and margins of leaves flat, narrow, and somewhat depressed bounded by the pair of ridges.
Leaves opposite decussate, short–lobed, sessile (appearing petiolate) to subsessile (the lowermost pair of leaves), without stipules; blade elliptic to oblong or ± linear in outline, < 15—50 mm long, with inrolled margins so base appearing narrow and petiolate, having to 4 teeth and short lobes per edge on margins, pinnately veined with principal veins sunken on upper surface and raised on lower surface (including “petiole”), hirsute hairs abundant on upper surface and along midrib on lower surface.
Inflorescence spike, terminal, many–flowered, 100+ × 6—7 mm, flowers alternate, closely spaced, bracteate, glandular–hirsute and glandular short–hirsute; rachis strongly ridged, with 3 ridges descending from each bractlet, internodes 2.5—4 mm long; bractlet ± ovate, 3 × 1.5 mm, ± = calyx, green or with purple at tip, with midvein raised on lower surface, with short and long glandular hairs having minute heads but later appearing nonglandular, upper surface nearly glabrous.
Flower bisexual, ± radial, ca. 4 mm across; calyx 4–lobed + 1 less prominent, ± 2.8 × 1.2 mm; tube 5–ribbed but 4–sided with 4 conspicuous angles, green with white furrows, long hairs having blisterlike bases (pustulate) mixed with shorter hairs, with long hairs along ribs and especially on rachis side; lobes at end of 4 ribs, fingerlike, 0.3—0.5 mm, purplish; corolla 2–lipped, 5–lobed, ca. 5 mm long; tube 0.7—0.8 mm long, white, expanded around ovary and slightly stricted above ovary; throat 2–colored, lower portion deep purple and 0.7 mm diameter distinguished internally from upper violet, narrowly funnel–shaped portion by a ring of short, stiff white hairs concealing the stamens, lower throat internally with white strip opposite stamens having short white hairs, upper throat internally with short hairs extending to lower lip; lips darker violet, upper lip 2–lobed, lobes rounded, ca. 1.5 × 1 mm, lower lip 3–lobed, obovate in outline, lateral lobes 1.5 mm long and central lobe to 2 mm long; stamens 4 in 2 pairs, attached to corolla in deep purple lower throat, the lower pair attached at top of corolla tube just above constriction, the upper pair attached just below ring of concealing hairs, subsessile; filaments short, white; anthers dorsifixed, dithecal, 0.25 mm long with wide connective, yellowish, longitudinally dehiscent; pollen whitish; nectary disc obscure, nectar not observed; pistil 1, 1.6—1.8 mm long; ovary superior, 4–lobed, 0.5 × 0.35 mm, green, 4–chambered, each chamber with 1 ovule; style terminal, white at base to green at tip, tip unequally branched with short lateral fork 0.1 mm long and enlarge branched 0.3 mm long.
Fruit schizocarp (microbasarium), of 4 dry, 1–seeded mericarps (nutlets), nutlets oblong–columnar somewhat 3–sided, 1.9—2.1 × 0.5—0.6 mm, brown to dark brown, out–facing side with 4 vertical rows of conspicuous pits, 2 flattish faces with numerous whitish to tan blisterlike papillae, 2 inner faces separated with a fine ridge, having an attachment scar at base of ridge and off to the side.
A. C. Gibson