1956 年 5 巻 4 号 p. 176-179
The seasonal fluctuation of the growth stage of weeds, the budding stage, the flowering stage and the fruiting stage, was observed(1952-1955)in Shiribeshi district, Hokkaido. Late in May, the kind and quantity of the budding weeds begin to increase suddenly, and reach the maximum period in June. But late in July they begin to decrease gradually and increase again in autumn. As the atomospheric and the underground temperatures here in June and September are almost the same, the temperature in these months is thought to be the most favorable for budding. The average temperature in June and September from 1952 till 1954 is as follows ; [figuie] The kind of the flowering weeds begins to increase early in July and reaches the maximum in the period from the middle of August to the early part of September. But, as the temperature descends, it begins to decrease in October, and early in November, only a few kinds of weeds remain as the remnants of late autumn. The kind of the fruiting weeds gradually increases late in August and most weeds bear seeds in the period between the latter part of August and the early part of October. But late in October, most seeds fall to the ground.