1. Boehmeria cylindrica (L.) Sw. (false nettle)

B. cylindrica var. drummondiana (Wedd.) Wedd.

Pl. 571 a, b; Map 2670

Plants perennial, unarmed, but often with sparse to dense, short, fine, soft or stiff (then roughened to the touch), nonstinging hairs, with rhizomes, the roots fibrous. Stems 40–150 cm long, erect or strongly ascending, unbranched or less commonly few- to several-branched. Leaves opposite or occasionally a few pairs subopposite, short- to long-petiolate, stipulate. Leaf blades 3–15 cm long, sometimes the pair at a node slightly unequal in size, lanceolate to elliptic, broadly elliptic, ovate, or broadly ovate, somewhat asymmetrically angled to rounded at the base, tapered at the tip, the margins sharply toothed, the venation with the 2 basalmost lateral veins more developed than the others; cystoliths rounded. Inflorescences axillary, small dense clusters arranged into short or elongate and interrupted spikes, these sometimes leafy toward the tips, the staminate flowers scattered among the pistillate flowers or in separate spikes (rarely the plants totally dioecious). Bractlets not forming an involucre. Staminate flowers with 4 sepals, these 0.7–1.1 mm long, cupped around the stamens. Stamens 4. Pistillate flowers with 4 sepals fused nearly to the minutely 2- or 4-toothed tip (the calyx appearing more or less flask-shaped, but flattened), 0.6–1.0 mm long, enclosing and fused to the ovary and fruit. Style elongate (exserted from the calyx), the stigmatic region linear. Fruits 0.6–0.8 mm long, remaining enclosed in the persistent calyx, which appears flattened, with a pair of thick wings, the surface with sparse to dense, ascending, sometimes hooked hairs. 2n=28. June–October.

Scattered to common nearly throughout the state, but uncommon or absent from northwesternmost Missouri (eastern U.S. west to Minnesota, Utah, and Arizona; Canada, Mexico, Central America, South America, Caribbean Islands; introduced in California). Bottomland forests, banks of streams, rivers, and spring branches, and fens; also roadsides.

Steyermark (1963) and some other authors have separated this species into two varieties. The typical variety, which is by far the most abundant and widespread of the two in Missouri, has glabrous or sparsely hairy stems; ascending to spreading, relatively long-petiolate leaves; leaf blades that are relatively thin, flat, long-tapered at the tip, only slightly roughened on the upper surface, and glabrous or sparsely hairy on the undersurface; and fruiting calyces that are glabrous or sparsely hairy with straight hairs and lack purple mottling. The var. drummondiana, which in Missouri tends to grow around the margins of some fens and spring branches in the Ozark Division, has been characterized as having moderately to densely hairy stems; drooping, relatively short-petiolate leaves; leaf blades that tend to be relatively thick, folded longitudinally, short-tapered at the tip, strongly roughened on the upper surface, and moderately hairy on the undersurface; and fruiting calyces that are densely hairy with straight and hooked hairs and with purple mottling. Although the extreme forms of the species can appear strikingly different, Wilmot-Dear and Friis (1995) and Boufford (1997b) noted that across the broad distributional range of the species, the characters listed tend to vary independantly and numerous intermediates are known. N. G. Miller (1971) suggested that the morphological differences may be reflections of habitat differences, rather than genetically based variation. The unpublished thesis studies of Stuyvesant (1984) tended to corroborate this.