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Crassocephalum crepidioides is often confused with:
Erechtites hieraciifolius Erechtites hieraciifolia L.
Plants that fill a similar niche:
Celosia argentea Form
Cyperus iria Cyperus iria
Sisymbrium irio Sisymbrium irio

Redflower Ragweed Crassocephalum crepidioides

Phonetic Spelling
kras-oh-SEF-uh-lum krep-pid-dee-OY-deez
Description

Thickhead, a weed in the Asteraceae (daisy) family, is a recently introduced summer annual that is very similar to the more common American burnweed (Erechtites hieraciifolius). It can be found growing in abandoned farm land, pastures, orchards, neighborhood gardens, plantations and wastelands. 

It will not flourish in shaded locations or where the landscape is dry.  Full sun and wet conditions are the optimum for spread.

Seedlings form a rosette of elliptic leaves with toothed margins; midveins are often tinged red. Compared to American burnweed, seedling leaves are thicker and more deeply veined. As plants mature they grow upright to about 4 feet with toothed leaves clasping the stem.

The red thickhead flowers lack petals. Additionally, thickhead flowers droop downward as though the plants were experiencing moisture stress. Seeds are wind-dispersed and can produce multiple generations each growing season.

The ability of each plant to produce up to 29 flowers, and each flower sending off approximately 150 wind-blown seeds, makes this plant difficult to control and highly aggressive.  Under the proper conditions, such as those experiences in southern Florida, it can bloom year round.  

Insects, Diseases, and Other Plant Problems:   Due to its weedy nature, eradication via hand weeding when the plant is small works best.  Removal of the flower heads before they bloom can also help to prevent spread of the seeds.  A layer of mulch between the falling/blowing seeds will prevent the seeds from reaching the underlying soil.  Thickhead is managed by most broad-spectrum herbicides. However, herbicide efficacy rankings for this species are based on limited experimental data.

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#heat tolerant#high maintenance#fast growing#herbaceous#wind dispersed seeds#annual weed#herbaceous annual#humidity tolerant#bee friendly#tropical#tropical annual#shade intolerant#edible#herb#annual#weed
 
Cultivars / Varieties:
Tags:
#heat tolerant#high maintenance#fast growing#herbaceous#wind dispersed seeds#annual weed#herbaceous annual#humidity tolerant#bee friendly#tropical#tropical annual#shade intolerant#edible#herb#annual#weed
  • Attributes:
    Genus:
    Crassocephalum
    Species:
    crepidioides
    Family:
    Asteraceae
    Life Cycle:
    Annual
    Recommended Propagation Strategy:
    Seed
    Country Or Region Of Origin:
    Tropical and Southern Africa and Madagascar
    Distribution:
    Fl, HI
    Wildlife Value:
    The flowers attract Seladonia and Small Carpenter Bees.
    Edibility:
    The entire plant is eaten as a vegetable in its native county.
  • Whole Plant Traits:
    Plant Type:
    Annual
    Weed
    Habit/Form:
    Erect
    Growth Rate:
    Rapid
    Maintenance:
    High
    Texture:
    Medium
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Soil Texture:
    Loam (Silt)
    Sand
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Frequent Standing Water
    Occasionally Wet
    Available Space To Plant:
    12 inches-3 feet
    USDA Plant Hardiness Zone:
    10a, 10b, 11a, 11b, 12a, 12b
  • Fruit:
    Fruit Color:
    Brown/Copper
    Red/Burgundy
    Display/Harvest Time:
    Fall
    Fruit Type:
    Achene
    Fruit Length:
    < 1 inch
    Fruit Width:
    < 1 inch
    Fruit Description:
    Tiny, reddish-brown achenes are attached to hairs that are spread by the wind.
  • Flowers:
    Flower Color:
    Orange
    Pink
    Red/Burgundy
    Flower Inflorescence:
    Cyme
    Flower Value To Gardener:
    Showy
    Flower Bloom Time:
    Fall
    Spring
    Summer
    Winter
    Flower Shape:
    Bell
    Flower Size:
    < 1 inch
    Flower Description:
    Drooping clusters of flowers without petals, ranging from reddish-pink to reddish-orange appear at the apex of the plant.
  • Leaves:
    Leaf Color:
    Gold/Yellow
    Green
    Leaf Feel:
    Fleshy
    Leaf Value To Gardener:
    Edible
    Leaf Type:
    Simple
    Leaf Arrangement:
    Alternate
    Opposite
    Leaf Shape:
    Elliptical
    Spatulate
    Leaf Margin:
    Entire
    Serrate
    Hairs Present:
    No
    Leaf Length:
    > 6 inches
    Leaf Width:
    3-6 inches
    Leaf Description:
    The leaves are light green with veins that are a light red. Newer leaves are alternate and elliptical.
  • Stem:
    Stem Is Aromatic:
    No
    Stem Cross Section:
    Round
    Stem Form:
    Straight
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    The stems are straight, round and ribbed. Thick hairs appear on portions of the stem and along the branches.
  • Landscape:
    Attracts:
    Bees
    Pollinators
    Resistance To Challenges:
    Heat
    Humidity
    Problems:
    Weedy