Summer weed vegetation of road pavement seams in Route 4.
Weed vegetation of road pavement seams was investigated at 68 points on Route 4 (from Adachi, Tokyo to Aomori city, Aomori) in Japan, from 27 to 30 July 2004. A total of 102 weed species belonging to 27 families were observed and 44 naturalized weeds (43%) were involved. The frequency of the occurrence of Digitaria ciliaris, Artemisia princeps, Taraxacum officinale and Setaria viridis were 85.3, 69.1, 61.8 and 60.3%, respectively. In terms of life form, annual, bolochory and monophyte weeds were dominant. These results were similar to those from studies conducted in Utsunomiya City in 2002 and 2003. On the other hand, when weed vegetations in a cool temperature (7 points in Iwate Pref.) and warm temperature regions (7 points in Tochigi Pref, Saitama Pref and Tokyo Met.) were compared, D. ciliaris and Eragrostis multicaulis occurred with similar frequency and coverage at both regions. However, T. officinale and Poa pratensis were abundant especially in the cool temperature region, and S. viridis and Conyza sumatrensis in the warm temperature regions.