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Iris pseudacorus

Image of Iris pseudacorus

Gerald L. Klingaman

Family

Iridaceae

Botanical Name

Iris pseudacorus

Plant Common Name

Pale Yellow Flag, Pale Yellow Iris

General Description

The fragrant yellow blooms of this aquatic iris are held above substantial clumps of green strap-like foliage. This vigorous perennial is native to Europe and western Asia, though it has naturalized in temperate regions across the world.

Pale yellow flag resides along the water´s edge and forms clumps that spread via fleshy rhizomes. The green to gray-green foliage is slender, tall and lightly ribbed. In the heat of summer, light yellow flowers appear on sturdy stems held above the leaves. The classic iris flowers have three drooping petals, called "falls", with violet-brown markings and three upright petals, called "standards." The flowers are visited by bees. After pollination, elongated, dry, three-chambered fruits appear, which are filled with dark seeds.

Grow pale yellow flag in full to partial sun in any soil that is organic-rich and waterlogged. Often it is grown in still shallow water along water edges, but can also be grown out of water in moist garden soil. The cultivar 'Alba' has nearly white blossoms, with hints of pale butter yellow, and 'Variegata' has foliage with pale green and yellow stripes. Many spectacular hybrids have been developed using pale yellow flag as a parent; however, these cultivars are generally not aquatic in nature.

Pale yellow flag is an aggressive plant that has escaped from cultivation in many regions across the globe. Never plant it in natural marshlands outside of its native distribution. Even controlled garden ponds should be avoided. In cultivation it is best grown in a container but will require regular division.

Characteristics

  • AHS Heat Zone

    8 - 3

  • USDA Hardiness Zone

    4 - 8

  • Sunset Zone

    A2, A3, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 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

    3'-5' / 0.9m - 1.5m

  • Width

    5'-6' / 1.5m - 1.8m

  • Bloom Time

    Late Spring, Early Summer, Summer

  • Native To

    Europe, Eastern Europe, Northern Europe, Southern Europe, Western Europe, Russia/Siberia, Mediterranean, Iraq, Iran, Western Asia

Growing Conditions

  • Soil pH

    Acidic, Neutral

  • Soil Drainage

    Poorly Drained

  • Soil type

    Clay, Loam, Sand

  • Tolerances

    Wet Site

  • Growth Rate

    Fast

  • Water Requirements

    Average Water, Ample Water

  • Habit

    Clump-Forming

  • Seasonal Interest

    Spring, Summer

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    Light Yellow, Chocolate

  • Flower Color Modifier

    Bicolor

  • Fruit Color

    Brown

  • Foliage Color (Spring)

    Green, Gray Green

  • Foliage Color (Summer)

    Gray Green, Dark Green

  • Foliage Color (Fall)

    Gray Green, Dark Green, Yellow Green

  • Fragrant Flowers

    Yes

  • Fragrant Fruit

    No

  • Fragrant Foliage

    No

  • Bark or Stem Fragrant

    No

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    No

  • Edible Fruit

    No

  • Showy Foliage

    Yes

  • Foliage Texture

    Medium

  • Foliage Sheen

    Matte

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Usage

    Bog Garden, Container, Water Gardens

  • Sharp or Has Thorns

    No

  • Invasive

    Yes

  • Self-Sowing

    Yes