5. Verbena simplex Lehm. (narrow-leaved vervain)

V. angustifolia Michx., an illegitimate name

Pl. 574 a–c; Map 2688

Plants perennial. Stems 10–70 cm long, erect or strongly ascending, moderately to strongly 4-angled, sparsely to moderately pubescent with nonglandular, straight, strongly ascending, occasionally pustular-based hairs. Leaves sessile or with a winged petiole, the blades 2–8(–10) cm long, 1–10(–15) mm wide, narrowly lanceolate to oblanceolate or linear, tapered to a slender, nonclasping base, mostly angled to a bluntly or sharply pointed tip, unlobed, the margins relatively finely toothed, both surfaces sparsely pubescent with appressed, nonglandular, occasionally pustular-based hairs, especially along the veins, the upper surface sometimes nearly glabrous. Inflorescences usually solitary spikes, 4–25 cm long, moderately dense (the flowers strongly overlapping except sometimes the lowermost ones), slender, elongating greatly with age. Bracts 3–5 mm long, slightly shorter than to slightly longer than the calyx, lanceolate. Calyces (2–)3–4 mm long. Corollas 4–6 mm long, the outer surface sparsely hairy toward the tip of the tube, funnelform to somewhat trumpet-shaped, dark lavender or purple to white or bluish-tinged, the tube relatively slender, the limb 4–6 mm in diameter. Nutlets 2–3 mm long, narrowly oblong to narrowly oblong-elliptic in outline, the inner surface usually slightly pale and smooth or with sparse to moderate, minute papillae, the outer surface greenish brown to reddish brown, with several longitudinal ridges, these with several cross-ridges above the midpoint. 2n=14. May–September.

Scattered nearly throughout the state, but apparently absent from the Mississippi Lowlands Division and uncommon in the northernmost counties (eastern U.S. west to Minnesota and Texas; Canada). Glades, tops of bluffs, upland prairies, and banks of streams and rivers; also pastures, old fields, railroads, roadsides, and open disturbed areas.

The name V. angustifolia Michx., which was applied to this taxon in some of the older botanical literature, is a later homonym of V. angustifolia Mill., a different species that is widespread in the Neotropics and is now called Stachytarpheta angustifolia (Mill.) Vahl by most botanists. Some authors (O’Leary et al., 2010) segregate populations of Verbena simplex from Baja California, Mexico with more spreading hairs on the foliage and somewhat glandular calyces as var. orcuttiana (L.M. Perry) N. O’Leary.