3. Physostegia virginiana (L.) Benth. (false dragonhead, obedient plant, Virginia lionsheart)

Pl. 439 e, f; Map 1980

Plants often with rhizomes. Stems 40–150 cm long, with 10–34 nodes below the inflorescence. Leaves progressively shorter toward the stem tip, the foliage leaves grading into the inflorescence bracts, the inflorescences appearing sessile or elevated from the foliage, then with 1 to several pairs of short or rarely elongate, closely to widely spaced (3–50 mm apart), empty bracts. Blades of main foliage leaves 2–18 cm long, (3–)10–40 mm wide, thin and flexible to thick and stiff, lanceolate to oblanceolate, oblong-lanceolate, often narrowly so, those of the lowermost leaves sometimes narrowly ovate, those of the median and upper leaves sometimes linear, sometimes with small basal auricles that clasp the stem, more commonly angled to a truncate or abruptly rounded base as wide as or slightly wider than the stem node, the margins sharply but sometimes finely toothed, sometimes mainly toward the blade tip. Axes of the inflorescences with uniform, dense, very minute hairs. Bracts 2–8 mm long (except sometimes the empty basal bracts longer), mostly shorter than the calyces at flowering, lanceolate to ovate. Calyces mostly somewhat overlapping along the inflorescence axis, 3–9 mm long at flowering, becoming enlarged to 4–11 mm at fruiting, the outer surface densely pubescent with very minute hairs. Corollas 8–35 mm long, white to lavender, pink. or pinkish purple. Nutlets 2–4 mm long. 2n=38. May–October.

Scattered nearly throughout the state, but uncommon in the Glaciated Plains and Mississippi Lowlands Divisions (eastern U.S. west to Montana, Utah, and New Mexico; Canada, Mexico). Glades, upland prairies, savannas, tops of bluffs, upland prairies, bottomland prairies, banks of streams, rivers, and spring branches, mesic upland forests, bottomland forests, swamps, acid seeps, and fens; also old fields, ditches, railroads, roadsides, and disturbed areas.

Physostegia virginiana is the most widespread and morphologically variable species in the genus. The Missouri plants (as keyed and described above) represent only a small portion of this variation. Cantino (1982) evaluated the several infraspecific taxa and segregate species accepted by some earlier authors and concluded that only two subspecies should be recognized. These equate roughly to southern and northern taxa, but there is a broad zone of geographic overlap (including Missouri). Steyermark (1963) segregated small-flowered plants as P. formosior, but Cantino (1982) indicated that these plants are part of a complex pattern of morphological variation within the species and that there exists no sharp discontinuities for corollas size within the species. Even restricting the infraspecific taxonomy to just a pair of subspecies, there are still a number of intermediate specimens. Complicating the issue is the existence of escapes from gardens. These often do not key well to subspecies. Occasional plants of P. virginiana growing in fens are reduced and take on the appearance of P. angustifolia. Such individuals with narrow leaves and apparently well-elevated inflorescences still have the pubescence of the inflorescence axis characteristic of P. virginiana.