Pycnanthemum albescens T. & G. - Mountain Mint

Pycnanthemum albescens plant

Family - Lamiaceae

Stems - From fibrous roots, multiple from the base, rooting at the lowest nodes, branching, herbaceous, 4-angled, fragrant, hollow, pubescent with both long and short and long hairs, to +1m tall, erect.

Pycnanthemum albescens stemStem at a node.

Leaves - Opposite, decussate, short-petiolate. Petioles to 6mm long, pubescent as the stem. Blades to +9cm long, -4cm broad, lanceolate to ovate-lanceolate, serrate (the tips of the serrations often white), green adaxially, whitish-green abaxially, punctate, pubescent (more so below).

Pycnanthemum albescens leaves

Inflorescence - Axillary and lateral capitate clusters of bractiate cymes. Pedicels +/-1mm long. Bracts subtending the inflorescence with a whitish bloom. Each division of the cyme subtended by a gradually reduced bract.

Pycnanthemum albescens inflorescence

Flowers - Corolla white, 6mm long, bilabiate. Corolla tube glabrous externally, pubescent internally. Lobes glandular and pubescent externally. Lower lip single-lobed. Lobe 4mm long, 1.5mm broad, white. Upper lip 3-lobed, 4-5mm broad. Lobes deflexed, spotted with purple internally. Central lobe bent forward at the apex. Lateral lobes shorter than the central. Stamens 4, subequal, exserted, adnate at the apex of the corolla tube, alternating with the corolla lobes. Filaments 4-5mm long, white, glabrous. Anthers .8mm long, orange. Style white, glabrous, exserted, 7-8mm long. Stigma unequally 2-lobed. Ovary 4-lobed, green. Lobes pubescent at the apex, +/-.5mm long. Calyx 5-lobed, weakly bilabiate, 4mm long, glandular punctate, covered by a dense whitish pubescence. Calyx tube glabrous internally. Upper lip 2-lobed. Lobes acute, to +1mm long. Lower lip shallowly 3-lobed or notched at the apex. Lobes pubescent internally.

Pycnanthemum albescens flowers

Flowering - July - September.

Habitat - Rocky open woods, grassy slopes, clearings over rocky substrates.

Origin - Native to U.S.

Other info. - This species can be found in the southern 1/4 of Missouri. It is common in the habitats mentioned above. The plant is easily identified by its whitish bracts. Like most species of this genus, the plant has a characteristic minty smell.
"albescens" means "becoming white" for the bracts of the inflorescence.

Photographs taken at the Peck Ranch Wildlife Refuge, Carter County, MO., 7-19-01, and near Stegal Mountain, Shannon County, MO., 8-10-03.


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