Abstract: An intergeneric artificial hybridization was conducted between Cunninghamia R. Br. And Cryptomeria D. Don The results are as follows: 1. A considerable number of hybrid seeds shed from 76 pollinated cones were empty and a total of 628 looks plump. Soft X-ray radiographs showed that, still and all, a majority of the "plump" seeds were embryoless (597, 95.6 % ) whereas some were partially-developed ( 17, 2.7 % ) and only a few were really full ( 14, 2.2 % ). 2. Germination test showed that all of the radiographed hybrid seeds with fully-developed embryos were genninable whereas those with partially-developed embryos were ungenninable. 3. Physiologically, the growth rate of hypocotyl, the date for shedding of seed coat and spreading of cotyledons, the elongation of epicotyl, and the branching of shoot of the 11-month old seedlings showed a tendency to fall behind those of the female parent; morphologically, the l 1-month old hybrid seedlings with linear leaves appeared rather short, slender and weak, whereas the seedlings of the female parents with linear-lanceolate leaves appeared rather tall, stout and strong. 4. It is considered that the hybrid may be true and the crossability reveals a close phylogenetic affinity of Cunninghamia with Cryptomeria.

Key words: Cunninghamia, Cryptomeria, Artificial hybridization, Soft X-ray