Pycnanthemum pilosum Nutt. - Hairy Mountain Mint

Pycnanthemum pilosum plant

Family - Lamiaceae

Stems - From fibrous roots and short, woody rhizomes, to +1m tall, erect, herbaceous but stout, 4-angled, villous, solid, single to multiple from the base, branching mostly in the inflorescence, entire plant fragrant.

Pycnanthemum pilosum stem

Leaves - Opposite, decussate, short-petiolate below, sessile above, lanceolate, with 2-4shallow teeth per margin, villous, to +/-5cm long, +/-1.5cm broad, light green, with numerous glandular punctations abaxially (use a lens to see).

Pycnanthemum pilosum leaves

Inflorescence - Terminal corymbiform cyme of many subglobose flower clusters. Each cluster subtended by an involucre of small linear-oblong bracts. Bracts acute to acuminate, tomentoulose, whitish-green, to +/-4mm long, 1.5mm broad, many. Each involucre usually immediately subtended by two reduced foliaceous bracts. Bracts spreading, opposite. Branches of inflorescence decussate, villous, each division of inflorescence with a pair of foliaceous opposite bracts. Total inflorescence to +/-25cm long (tall). Flowers sessile, +/-40 per head.

Flowers - Corolla zygomorphic, bilabiate, white to pink with purple spots internally. Corolla tube 4mm long, glabrous basally, villous apically, villous internally, 4-lobed. Upper lip single-lobed. Lobe +/-3mm long, +/-1.5mm broad, glabrous internally. Lower lip 3-lobed. Central lobe longer than the lateral lobes, to 4mm long, 1.4mm broad, rounded at the apex, with a slightly wavy apical margin. Lateral lobes 2mm long, 1.5mm broad. Lower lip bearded internally. Style 1, exserted from between the ovaries and from under the upper lip, glabrous, white, +/-9mm long. Stigmas unequal. Ovary green, 4-parted to about 1/3 or 1/2 its length, 1mm long (total) in flower, glabrous basally, with long erect white hairs apically. Each division of the ovary about .2mm long. The base of the ovary a green nectary. Stamens 4, didynamous, adnate at the apex of the corolla tube, partially exserted. Filaments white, glabrous, to -2mm long. Anthers yellow to pink when fresh, quickly drying to brownish-red, .3mm long.

Pycnanthemum pilosum flowers

Flowering - June- September.

Habitat - Prairies, open dry woodland, thickets, railroads.

Origin - Native to U.S.

Other info. - This attractive species can be found throughout Missouri. The plant is fairly easy to identify becasue of its lanceolate, opposite leaves, villous, 4-angled stems, and dense terminal clusters of flowers. Like the other members of this genus, the plant has a strong fragrance and can be made into a tea.

Photographs taken near Big Spring Park, MO., 7-8-04.


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