1. Pycnanthemum albescens Torr. & A. Gray (white mountain mint)
Pl. 439 j, k;
Map 1982
Stems
40–90(–150) cm long, pubescent on the angles and sides with a mixture of
moderate to dense, short, curled hairs and sparser, longer, spreading hairs.
Leaves sessile or short-petiolate, the largest leaves with the petioles 4–12 mm
long. Leaf blades 2.5–7.0 cm long, 15–25 mm wide, ovate to broadly lanceolate
or narrowly elliptic, angled or tapered at the base, the margins often finely
toothed; the upper surface of the lower and median leaves sparsely to densely
short-hairy and usually somewhat grayish, that of the uppermost leaves usually
whitened with dense, short, curled hairs; the undersurface of all of the leaves
pale or whitened with dense, short curled hairs and occasionally with a few
longer, spreading hairs along the veins. Inflorescences relatively open, often
appearing broadly rounded, the branches mostly observable, at least at
fruiting. Bracts leaflike, whitened with dense, short, curled hairs on usually
both surfaces. Bractlets 2–4 mm long, linear to narrowly lanceolate. Calyces
3.5–5.0 mm long, zygomorphic, 2-lipped, densely pubescent with minute,
appressed hairs, lacking longer bristly hairs on the margins or tip, the upper
lip shallowly 3-lobed, the lobes 0.4–0.6 mm long, triangular, bluntly pointed,
the lower lip more deeply 2-lobed, the lobes 1.0–1.5 mm long, ovate to oblong-ovate,
bluntly pointed. Corollas 5–8 mm long, white to pale lavender. Nutlets 1.0–1.4
mm long, hairy toward the tip. 2n=38. July–September.
Scattered mostly
in the Ozark and Mississippi Lowlands divisions (Kansas to Texas east to
Kentucky and Florida). Mesic to dry upland forests, savannas, sand prairies,
ledges of bluffs, and acid seeps; also pastures and old fields.
Where this
species grows in proximity to P. muticum and P. pilosum, rare
putative hybrids have been collected. E. Grant and Epling (1943) noted the
existence of two races within P. albescens, with plants in the Gulf
Coastal portion of the species range having stems with uniformly short, curled
hairs, this pubescence type grading into plants with a mixture of such shorter
hairs and longer, spreading ones. Missouri plants are typical of the latter
race.