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Pentanema britannicum

Previously known as:

  • Inula britannica
Phonetic Spelling
pen-ta-nee-ma brit-AN-ee-kum
Description

British yellowhead, in the Asteraceae (daisy) family, is a very recent introduction to North America. A native of Europe, this creeping perennial weed has been introduced to several nurseries in contaminated hostas and daylilies from the Netherlands. Once introduced, the plant spreads aggressively by thick, fleshy roots that produce new shoots.

Plants form rosettes of long, thin leaves that resemble some asters or fleabanes. The leaves also resemble buckhorn plantain leaves except plantain leaves have five distinct parallel veins; Inula leaves have netted veins. Leaves are up to 2 inches inches long and about 1/2 to 1 inch wide. Leaves remain green through the winter. Plants require a chilling period to flower. In the spring plants spread rapidly, then in early to mid-summer flowering stems begin to elongate. Plants produce attractive, typical aster-like flowers, yellow to light orange in color. They are found growing along river and stream margins, marshes, ditches, and wet woods and grasslands. However, it is an adaptable plant to other areas.

It is unclear whether or not the species produces viable seeds in North America. Because the plant primarily reproduces vegetatively, preemergence herbicides commonly used are not effective. It is nearly impossible to remove all of the root pieces; consequently, if a container plant is infested with British yellowhead it should be destroyed before the weed can spread.

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#biennial#perennials#weeds#yellow flowers#weedy#high maintenance#aggressive#creeping#spreading#rhizomes#rhizomatous#lawn weed
 
Cultivars / Varieties:
Tags:
#biennial#perennials#weeds#yellow flowers#weedy#high maintenance#aggressive#creeping#spreading#rhizomes#rhizomatous#lawn weed
  • Attributes:
    Genus:
    Pentanema
    Species:
    britannicum
    Family:
    Asteraceae
    Uses (Ethnobotany):
    Naturalize
    Life Cycle:
    Biennial
    Perennial
    Country Or Region Of Origin:
    Europe to Russian Far East and Himalaya
    Distribution:
    New York, Michigan, Minnesota, and Oregon
    Dimensions:
    Height: 1 ft. 0 in. - 1 ft. 6 in.
    Width: 0 ft. 9 in. - 2 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Perennial
    Weed
    Woody Plant Leaf Characteristics:
    Deciduous
    Habit/Form:
    Creeping
    Growth Rate:
    Rapid
    Maintenance:
    High
    Texture:
    Medium
  • 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 Drainage:
    Moist
    Occasionally Wet
    Available Space To Plant:
    Less than 12 inches
    USDA Plant Hardiness Zone:
    5b, 5a, 6b, 6a, 7b, 7a, 8b, 8a
  • Fruit:
    Fruit Color:
    Brown/Copper
    Gold/Yellow
    Display/Harvest Time:
    Fall
    Fruit Type:
    Achene
    Fruit Length:
    < 1 inch
    Fruit Width:
    < 1 inch
    Fruit Description:
    Yellowish brown bristly achene with a few hairs near the tip
  • Flowers:
    Flower Color:
    Gold/Yellow
    Orange
    Flower Inflorescence:
    Head
    Flower Bloom Time:
    Summer
    Flower Shape:
    Radial
    Flower Petals:
    more than 20 petals/rays
    Flower Description:
    Many yellow ray flowers surround many center disc flowers Blooms July to Aug.
  • Leaves:
    Woody Plant Leaf Characteristics:
    Deciduous
    Leaf Color:
    Green
    Leaf Arrangement:
    Rosulate
    Leaf Shape:
    Elliptical
    Lanceolate
    Leaf Margin:
    Entire
    Serrate
    Hairs Present:
    Yes
    Leaf Length:
    3-6 inches
    Leaf Width:
    < 1 inch
    Leaf Description:
    Narrow lance-shaped leaves up to 2 inches long. They are stalkless and surround the stem at the base. They are often arching with rough hairs on the undersides along the veins. The margins are slightly revolute and entire to toothed.
  • Stem:
    Stem Color:
    Brown/Copper
    Red/Burgundy
    Pith (Split Longitudinally):
    Coninuous diphragmed
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    Erect reddish-brown stems with a few hairs on the lower part only
  • Landscape:
    Problems:
    Weedy