| Parthenium hysterophorus L. |
| ASTERACEAE |
| ragweed parthenium, parthenium weed, ragweed, Santa Maria feverfew, bitter weed, carrot grass, congress grass, false ragweed, ragweed parthenium, whitetop, demoina weed |
| indodengaziwa |
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Invasive, Major problem species |
| Origin: Tropical America, Caribbean |
| Growth Form: Herb |
| Plant Description: Plant: Annual herb, 0.3–1.5 m high, with an erect, longitudinally grooved stem and deep tap-root; stems and leaves shortly hairy; regular contact with the plant causes allergenic dermatitis and asthma.
Leaves: Pale green with some of the hairs containing allergens; rosette and lower stem leaves deeply pinnately lobed, 80–200 mm long; upper stem leaves shorter, less divided.
Flowers: White, bisexual, in small compact heads, about 3 mm across, on slender peduncles in a terminal, open panicle, September–May.
Fruit: Achenes; seeds black, 2 mm long. |
| Key Features: |
| Control: |
| Comments: |
More information:
Weeds & Invasive Plants Home Page
NRCS Plants Database
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Illustration
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada.
Photo - plant
Larry Allain @ USDA-NRCS PLANTS Database
Photo - plant
K Braun, Swaziland's Alien Plants Database
Photo - plants
Rob Mackenzie, Swaziland's Alien Plants Database
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| KEY |
 Confirmed (herbarium specimen) |
 Visual record |
 Suspected |
| Click on map grid square to view record information for each grid square. |
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