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Ambrosia trifida

Basic information
Scientific name Ambrosia trifida

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オオブタクサ
Common names Giant Ragweed, Great Ragweed, Buffalo Weed, Horse Weed
Higher taxon Asteraceae, Asterales, Magnoliopsida, Magnoliophyta
Natural range North America.
Habitat Farm area, fruit garden, pasture field, riverside, roadside, vacancy, etc.
Invasion information
Range in Japan Almost entire Japan including Okinawa. Range in Japan
Origin Unknown.
Date The first record was in 1952 at Chiba Pref. and Shimizu Port of Shizuoka Pref.
Route Accidental: With agriculture products such as grains or beans.
Impact Actual: Competition with native plant, crop, pasture, etc. Allelopathy. Parasite (insects, fungi). Allergen for hay fever.
Affected organism: Native plants such as Primula sieboldii, crops, pasture, etc. (competition). Human (health damage).
Regulation in Japan No action for prevention, mitigation, control, or eradication.
Introduced range in other countries Europe, Asia
Reference Notes
  • Ecol Soc Jpn (ed) (2002) Handbook of Alien Species in Japan. Chijinshokan, Tokyo (in Jpn)
  • Osada (1976) Colored Illustrations of Naturalized Plants of Japan. Hoikusha, Osaka (in Jpn)
  • Shimizu (ed) (2003) Naturalized Plants of Japan. Heibonsha, Tokyo (in Jpn)
  • etc.
100 of the Japan’s Worst Invasive Alien Species.
South Korea prohibits importation of this species.