Ambrosia trifida

Basic information
Scientific name	Ambrosia trifida	Click to magnify
Major synonym	Ambrosia trifida var. integrifolia
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.
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. Native organism(s) affected: 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.