Characteristics of orchardgrass populations collected in 7 regions in Japan were studied for a period of 5 years. Populations from the Kanto region showed the best performance, indicating a high adaptation to the region. Factors which had contributed to the differentiation of ecotype populations in Kanto were discussed. Characters of several introduced subspecies of Dactylis glomerata L. were evaluated in relation to their native habitats. Subsp. marina from the sub-tropical coastal region differed from the others by the high degree of greenness in winter. Subspecies himalayensis was very late in heading. Subsp. lusitanica from Portugal showed good growth under short daylength. Populations of the subspecies of Dactylis glomerata L. collected in Morocco and Portugal were evaluated at NGRI, Japan. Fresh weight was low throughout the year in the populations from Morocco and high in those from Portugal. Many populations from Portugal displayed better growth in late autumn. Examination of the characteristics of populations in relation to the local climatic conditions indicated that fresh weight and leaf size increased in accordance to the increase of rainfall in the collection districts.