1983 年 33 巻 2 号 p. 149-160
In Aomori prefecture, northen part of Japan, three indigenous and one naturalized Plantago species are distributed severally in particular habitats that have distinctly different substratums, especially in respect to physical compositions and consequently to the water status in the soil layer to which the Plantago roots distribute. P. japonica habitats are restricted to very wet depressions along the seaside, accumulated with sandy loam, where the water content in the root layer always retains much higher levels than field capacity due to the inflow of fresh water from the neighbourhood. P. asiatica lives on compact loam soil of which the available water content remains nearly constant at relative high values above 75 mm throughout the growing season. The habitats of P. lanceolata, a naturalized species, is confined to well drained waste grounds where the soil layer contains much sand, much gravel, or both. Accordingly, the available water content remains at values lower than 50 mm throughout the main growing period. Among habitats of P. camtschatica, the physical composition of the soil was largely different, such as compact loam soil at a very disturbed pathway, sandy loam at a moderately disturbed slope, and sandy gravel soil at a moderately disturbed seaside. Therefore, the water contents of three habitats of P. camtschatica ranged from 100 to 148,50 to 90,and 15 to 48 mm, respectively.