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Mountain Mint Pycnanthemum flexuosum

Previously known as:

  • Brachystemum muticum
Phonetic Spelling
pik-NAN-thee-mum fleks-yoo-OH-sum
Description

Mountain mint is a NC native perennial in the Lamiaceae (mint) family found primarily in the coastal and Piedmont areas of the state. The genus name Pycnanthemum comes from the Greek word  pyknos means dense and anthos which means flower referring to the clustered tufts of white flowers that adorn the plant in the late summer.   The speices name flexuosum is Latin for pliant and is likely in reference to its bendable square stems.

Mountain mint prefers rich loamy moist soil with good drainage in full sun to partial shade. Wihle it grows on a variety of soils types and pH conditions, in its native habitat, it is found growing on alkaline soil.  It will tolerate drier conditions once established.  Unlike other members of the mint family, mountain mint grows slowly by underground rhizomes. It forms a clumping pattern on erect stems with fragrant narrow green foliage 2 to 3 feet tall and 1 to 3 feet wide.  Plants can be easily divided to propagate and should be every other year to maintain the best appearance.

In late summer it is topped by rounded clusters of white to lavender tubular flowers. The flowers attract pollinators including bees, butterflies and wasps. The dried capsule fruits provide interest in the winter landscape.  It is resistant to browsing by rabbits and deer.

Plant in the middle of a border in a sensory, pollinator, or native garden and enjoy all the wildlife it will bring to the landscape.  They work well along a woodland margin, in a rain garden or to help prevent erosion along a slope.  Or mass plant it in a meadow or other naturalized area or near a pond or streambank.  The light green leaves contrast nicely with purple leaved plants. Because of its strong upright appearance plan to plant shorter plants in front.

Insects, Diseases, and Other Plant Problems:  No serious problems.

See this plant in the following landscapes:
Native Plant Demonstration Garden All Saints' Episcopal Church
Cultivars / Varieties:
Tags:
#rain garden#perennials#white flowers#wildlife plant#moths#fragrant leaves#native perennials#nectar plant#low maintenance#winter interest#slopes#swallowtail butterflies#rabbit resistant#erosion control#stream banks#pond margins#NC native#deer resistant#native garden#pollinator plant#larval host plant#NC Native Pollinator Plant#flowers late summer#sensory garden#border middle#dry soils tolerant#butterfly friendly#nectar plant late summer#host plant#winter fruits#meadows#woodland garden#wavy-lined emerald butterfly#erect
 
Cultivars / Varieties:
Tags:
#rain garden#perennials#white flowers#wildlife plant#moths#fragrant leaves#native perennials#nectar plant#low maintenance#winter interest#slopes#swallowtail butterflies#rabbit resistant#erosion control#stream banks#pond margins#NC native#deer resistant#native garden#pollinator plant#larval host plant#NC Native Pollinator Plant#flowers late summer#sensory garden#border middle#dry soils tolerant#butterfly friendly#nectar plant late summer#host plant#winter fruits#meadows#woodland garden#wavy-lined emerald butterfly#erect
  • Attributes:
    Genus:
    Pycnanthemum
    Species:
    flexuosum
    Family:
    Lamiaceae
    Uses (Ethnobotany):
    Used in herbal medicine
    Life Cycle:
    Perennial
    Country Or Region Of Origin:
    Southeastern U.S.A
    Distribution:
    AL, FL, GA, MS, NC, SC, VA
    Wildlife Value:
    Attracts pollinators including bees, butterflies, moths, and wasps. Swallowtail butterflies nectar at the flowers. A larval host plant for the Gray Hairstreak butterfly and Wavy-lined Emerald (Synchlora aerata).
    Dimensions:
    Height: 2 ft. 0 in. - 3 ft. 0 in.
    Width: 1 ft. 0 in. - 3 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Native Plant
    Perennial
    Habit/Form:
    Clumping
    Erect
    Spreading
    Growth Rate:
    Slow
    Maintenance:
    Low
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Partial Shade (Direct sunlight only part of the day, 2-6 hours)
    Soil Texture:
    Clay
    High Organic Matter
    Loam (Silt)
    Sand
    Shallow Rocky
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Good Drainage
    Moist
    Occasionally Dry
    NC Region:
    Coastal
    Mountains
    Piedmont
    USDA Plant Hardiness Zone:
    5b, 5a, 6b, 6a, 7b, 7a, 8b, 8a
  • Fruit:
    Display/Harvest Time:
    Winter
    Fruit Type:
    Capsule
    Fruit Description:
    Capsules are dry, attractive in the winter
  • Flowers:
    Flower Color:
    Purple/Lavender
    White
    Flower Inflorescence:
    Cyme
    Flower Value To Gardener:
    Fragrant
    Flower Bloom Time:
    Summer
    Flower Shape:
    Tubular
    Flower Size:
    < 1 inch
    Flower Description:
    Terminal dense globular clusters which are 1 1/2" across of tiny 1/4" white to lavender tubular flowers with purple spots. Each flower has a calyx composed of 5 off-white sepals that protects the flower bud and then supports the flower. Once the flowers fade the sepals remain and give the globular head a fuzzy appearance. Blooms late summer. for about 2 months.
  • Leaves:
    Leaf Color:
    Green
    Leaf Value To Gardener:
    Fragrant
    Deciduous Leaf Fall Color:
    Red/Burgundy
    Leaf Type:
    Simple
    Leaf Arrangement:
    Opposite
    Leaf Shape:
    Elliptical
    Lanceolate
    Leaf Margin:
    Crenate
    Hairs Present:
    No
    Leaf Length:
    1-3 inches
    Leaf Description:
    Thick oval to lance-shaped green leaves 2-2 1/2 inches long with short petioles, toothed margins are red-tinged in fall. The fragrance is reminiscent of spearmint.
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
    Stem Cross Section:
    Square
    Stem Description:
    Branched green square stems
  • Landscape:
    Landscape Location:
    Meadow
    Naturalized Area
    Pond
    Slope/Bank
    Woodland
    Landscape Theme:
    Butterfly Garden
    Garden for the Blind
    Native Garden
    Pollinator Garden
    Rain Garden
    Winter Garden
    Design Feature:
    Border
    Attracts:
    Butterflies
    Moths
    Pollinators
    Predatory Insects
    Resistance To Challenges:
    Deer
    Dry Soil
    Erosion
    Rabbits