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SENNA hebecarpa

Image of Senna hebecarpa

James H. Schutte

Family

Fabaceae

Botanical Name

SENNA hebecarpa

Plant Common Name

American Senna

General Description

What a midsummer knockout! American senna's tall stature and large panicles of bright golden yellow flowers shine in the bright sun. An herbaceous perennial, this wildflower is native to prairies, old-fields and open woodlands from Ontario south to Wisconsin, Tennessee and Georgia. Fall frosts kill the plant to the roots, but the dry stems and seed pods persist into the winter before collapsing and decaying providing some visual interest.

Rising from the warm soil in mid- to late-spring, America senna quickly grows to become a tall, upright plant with fine, compound leaves. The rich green leaves alternate in a whorl on the stems. Each leaf comprises numerous oblong leaflets. In mid- to late-summer, panicles of five-petaled yellow blossoms appear along the upper stems. Bees pollinate the flowers, resulting in the production of seed pods. Hummingbird visits are also possible. The short pods turn chocolate brown and persist into fall, adding visual color and texture, though they can self-sow prolifically, so it may be wise to remove the pods before they shatter.

Easy-to-grow from seed, American senna is best grown in full sun in nearly any well-drained soil. It grows in average loam to moist sand with a neutral pH. Appreciating moist soil, it tolerates drought once established. Cut back dead stems in late fall to early winter. This senna is ideal for a tall mixed perennial border or in a meadow garden among purple coneflowers, wild bergamot and other prairie wildflowers. Over time, American senna creates a wider clump of many stems. The cloudless sulfur butterfly species lays its eggs on this perennial and the larvae consume it as their chief food source. Once heavily used in American perennial borders in the 19th century, it's rarely planted today.

American senna's leaflets are smaller than and produces more flowers compared to the Maryland senna (Senna marilandica). Both are perennials, but the Maryland senna is native to a larger, more southern range.

Characteristics

  • AHS Heat Zone

    10 - 3

  • USDA Hardiness Zone

    3 - 9

  • Sunset Zone

    A3, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Perennial

  • Sun Exposure

    Full Sun, Partial Sun

  • Height

    4'-5' / 1.2m - 1.5m

  • Width

    3'-3' / 0.9m - 0.9m

  • Bloom Time

    Summer, Late Summer

  • Native To

    Northeastern United States, Mid-Atlantic United States, Southeastern United States, North-Central United States, Canada

Growing Conditions

  • Soil pH

    Neutral

  • Soil Drainage

    Average

  • Soil type

    Loam, Sand

  • Growth Rate

    Medium

  • Water Requirements

    Drought Tolerant, Average Water

  • Habit

    Upright/Erect

  • Seasonal Interest

    Summer, Fall

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    Yellow, Gold

  • Fruit Color

    Brown, Chocolate

  • Foliage Color (Spring)

    Green

  • Foliage Color (Summer)

    Green

  • Foliage Color (Fall)

    Green

  • Fragrant Flowers

    Yes

  • Fragrant Fruit

    No

  • Fragrant Foliage

    No

  • Bark or Stem Fragrant

    No

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    Yes

  • Edible Fruit

    No

  • Showy Foliage

    Yes

  • Foliage Texture

    Coarse

  • Foliage Sheen

    Matte

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Usage

    Cutflower, Feature Plant, Mixed Border, Wildflower

  • Sharp or Has Thorns

    No

  • Invasive

    No

  • Attracts

    Butterflies

  • Self-Sowing

    Yes