7. Verbena urticifolia L. (white vervain, nettle-leaved vervain)
Pl. 574 d, e;
Map 2690
Plants
perennial. Stems 50–150(–250) cm long, erect or strongly ascending, moderately
to strongly 4-angled, moderately pubescent with nonglandular, straight or
somewhat curved, spreading, sometimes pustular-based hairs, often with shorter,
ascending hairs toward the tip. Leaves short- to moderately petiolate, the petiole
usually winged above the midpoint, the blades (2–)5–12(–20) cm long, at least
those of the largest leaves (10–)20–70(–120) mm wide, broadly lanceolate to
oblong-lanceolate or ovate, rounded or short-tapered to a nonclasping base,
tapered to a sharply pointed tip, unlobed, the margins relatively coarsely and
sometimes doubly toothed, both surfaces glabrous to moderately (rarely densely)
pubescent with spreading to loosely appressed, nonglandular, sometimes
pustular-based hairs. Inflorescences usually panicles of several to numerous
spikes, these 8–50 cm long, relatively open (the flowers not overlapping),
slender, elongating greatly with age. Bracts 0.5–1.5 mm long, shorter than the
calyx, ovate to narrowly ovate. Calyces 1.5–2.5 mm long. Corollas 2–4 mm long,
the outer surface sparsely to moderately hairy, especially toward the tip of
the tube, funnelform, white, the tube relatively slender, the limb 1–2(–3) mm
in diameter. Nutlets 1.5–2.0 mm long, oblong to narrowly oblong or
oblong-elliptic in outline, the inner surface usually slightly pale and smooth
or with sparse to moderate, minute papillae, the outer surface yellowish brown
to reddish brown, smooth or with several longitudinal ridges, these sometimes
with a few cross-ridges toward the tip. 2n=14. May–October.
Scattered nearly
throughout the state (eastern U.S. west to North Dakota and Texas; Canada,
Mexico). Banks of streams and rivers, margins of ponds, and lakes, openings of
bottomland and mesic upland forests, and occasionally savannas; also pastures,
old fields, fencerows, margins of crop fields, railroads, roadsides, and open
disturbed areas.
Plants with the
leaf undersurface densely short-hairy and slightly shorter calyces and nutlets
have been called var. leiocarpa L.M. Perry & Fernald. This variety,
which occurs nearly throughout the species range, seems to intergrade freely
with the less hairy var. urticifolia and thus should not be provided
with formal taxonomic recognition. Steyermark (1963) noted the existence of
such plants elsewhere, but excluded the taxon from the Missouri flora. Moldenke
(1980) reported the variety from Greene and Shannon Counties, but without
supplemental information or citation of a voucher specimen. Thus far, no
specimens have been discovered with this extreme morphology, although a number
of seemingly intermediate specimens from mostly eastern Missouri have been
collected.