3. Stachys pilosa Nutt. (woundwort, marsh betony)

S. pilosa var. arenicola (Britton) G.A. Mulligan & D.B. Munro

S. arenicola Britton

S. palustris L. var. arenicola (Britton) Farwell

S. palustris var. homotricha Fernald

S. palustris var. nipigonensis Jenn.

S. palustris var. phaneropoda Weath. ex Fernald

S. palustris var. pilosa (Nutt.) Fernald

S. palustris ssp. pilosa (Nutt.) Epling

Pl. 443 h, i; Map 2002

Stems 30–100 cm long, pubescent on the sides and angles with moderate, shorter or longer, occasionally gland-tipped, downward-angled to loosely spreading hairs, some of these usually pustular-based, often with a denser transverse line of sometimes longer, finer hairs at the nodes. Leaves sessile or short-petiolate, the petioles all less than 7 mm long. Leaf blades 3–10 cm long, lanceolate, oblong-lanceolate, oblong-elliptic, oblong-oblanceolate, or narrowly ovate-triangular, angled to rounded or sometimes shallowly cordate at the base, angled or more commonly tapered to a sharply pointed tip, the upper surface moderately pubescent with short, loosely appressed, sometimes pustular-based hairs, the undersurface sparsely to moderately pubescent with short, fine hairs. Inflorescences interrupted or more commonly loosely continuous spikes, the nodes well-spaced to somewhat crowded. Calyces 6–10 mm long, the tube sparsely to moderately pubescent with fine, sometimes gland-tipped hairs and/or coarser, nonglandular, sometimes pustular-based hairs, the lobes 3.0–4.5 mm long, hairy similar to the tube. Corollas 12–15 mm long. 2n=68. June–September.

Apparently absent from the Unglaciated Plains Division and most of the Ozarks, scattered elsewhere in the state (nearly throughout the U.S. [including Alaska], except some southeastern states; Canada). Bottomland forests, swamps, banks of streams, rivers, and sloughs, margins of ponds and lakes, bottomland prairies, moist swales in upland prairies and sand prairies, marshes, and fens; also ditches, railroads, roadsides, and moist, disturbed areas.

Stachys palustris and its allies form a polyploid complex that is morphologically very complex (Mulligan and Munro, 1983, 1989). True S. palustris is a hexaploid (2n=102) native to Europe that has become introduced sporadically in the northeastern United States and Canada. It differs from the native North American populations (S. pilosa) in a number of subtle features, including light purple (vs. white to light pink) corollas and calyx lobes tapered from near the base (vs. tapered from about the midpoint). Mulligan and Munro (1989) attempted to divide the North American populations into two groups, based primarily on differences in stem pubescence: the northeastern var. arenicola was characterized by stiff, downward-angled hairs; the western and northern var. pilosa was said to differ in softer mostly spreading hairs. The Missouri populations, which fall within the broad region of geographic overlap between these varieties, exhibit bewildering variation in pubescence styles, from stiff, stout, pustular-based hairs to fine, nonpustular hairs, the latter sometimes gland-tipped. Many plants possess both types of hairs, with the density of each dependent upon position on the stems. Thus, it seems impractical to recognize varieties for this species.