Chamaecyparis

There are six species in the genus, two of which occur in Japan. One, ‘Hinoki’ (Cha-maecyparis obtusa) produces one of the best quality woods in Japan, a very durable wood which has been used traditionally for poles and foundations of Japanese houses. C. obtusa is thus as important in Japanese forestry as Cryptomeria japonica. A large quantity of seeds is required each year to meet the demand for planting stock. Methods of promoting flowering, such as root pruning and ringing, have been used traditionally for this purpose. However, in 1958 treatment with gibberellin A₃ (GA₃) was found to promote flowering of C. obtusa. ^{6 , 66} Since then, much research has been carried out to establish practical methods of using GA₃ in the promotion of flowering. However, the flowering response of C. obtusa to GA₃ is much less pronounced than that of Cryptomeria. Thus, many attempts have been made to improve flowering in C. obtusa by combinations of GA₃ with other growth-regulating substances, and/or with ringing or girdling. Generally, however, these combination treatments are effective mostly with precocious and profusely flowering clones, but not with the recalcitrant clones, where flowering is sporadic or occurs late in the life of the tree.