Prelim inary Study on Nyssa Spec ies Introduction in Ea stern Pla in of China

Four tree species of the genus N yssa from southern America were introduced. Of them, N. aquatica andN. sy lvatica var. bif lora had been p lanted in p lain sites of Zhejiang, J iangsu, J iangxi, and Shanghai for 3～4 years.Theirmorphological characters, growth, adap tability, and waterlogging tolerance were emphatically investigated incomparison with N. sinensis, which ranges in mountain area of southern China. The sap lings of the two exotic treespecies had good growth in most p laces and had not freeze damage, diseases and insect pests. N. aquatica had betterheight growth than N. sylvatica var. bif lora and N. sinensis. The two foreign species showed high water demand andwaterlogging tolerance, so could be popularized in low, wet p lain. The key for their successful culture is to maintainenough water supp ly, such as to make seeds stratification by sowing, to choose low and wet site for seedling-raisingand p lanting, and to keep from soil aridity.