树木在长期系统发育过程中,受自然环境和人工栽培的影响,会产生变异,在繁殖过程中,常发现有不同类型的苗木出现。1975年秋,我们在观察水杉生长和落叶情况时,发现有的叶变色早,有的变色迟;有的树冠较大,有的较小;有的羽叶较短,有的较长。总之,个体之间的差异较大。为了进一步研究和利用优良类型,我们对苗木个体差 Trees in the long-term phylogenetic process, under the influence of the natural environment and artificial cultivation, will produce variation in the breeding process, often found in different types of seedlings appear. In the autumn of 1975, when we observed the growth and deciduous leaves of Metasequoia, we found that some of the leaves discolored earlier and some had discolored later; some had larger canopies and some were smaller; others had shorter ones and longer ones. In short, the difference between individuals is larger. In order to further research and use of good type, we are poor individual seedlings