One of the studies on the breeding of Alnus species, morphological and cytological observations have been conducted in Alnus hirsuta TURCZ. and Alnus hirsuta var. microphylla KUSAKA. Results obtained will be summarized as follows;
1) Leaf area of A. hirsuta was larger 70 percent than A. h. microphylla in proportion of increases of the length and breadth of leaf blade. One of the noticeable difference was shown in the interval of the secondary vines as shown Table 1.
2) Remarkable differences have been observed on the size of guard cells of stomata and on the number of stomata per unit area as shown in Table 4 and 5.
3) Length of male clusters in A. hirsuta was larger 18 percent than A.h. microphylla and the same result was observed on the size of pollen grains as shown Table 6 and 7.
4) Chromosome number have been observed using root tip cells. Preparation of slides were made by two methods, one is the paraffin method, stained in gentian violet or acid hematoxylin and the other one is the squash method in acetic orcein. Number of chromosome in A. hirsuta was counted 2n=28, this is correspondent with the basic diploid number which had been already reported. In the case of A. h. microphylla 2n=14 was counted, it will be new case in Alnus species. On the basic number of Alnus species will be discuss in the future report.