分布在美国东北部广阔地区的黑胡桃的姐妹树种灰桃树过去虽未遍布,但毕竟比现在分布范围广。目前,一种由真菌引起的溃疡病正在逐步地毁灭灰胡桃树,其前景令人担忧。除了在西弗吉尼亚和威斯康星能发现一些无病的灰胡桃树外,在北卡罗来纳西部已找不出一棵无病的灰胡桃树,其它各地的情况几乎与它相同。 Distributed in the vast north-eastern region of the black walnut sister species of peach trees in the past though not yet widespread, but after all, a wide range of distribution than now. Currently, a fungal-caused ulcer disease is gradually destroying the walnut tree, its prospects are alarming. Except for some disease-free gray walnut trees found in West Virginia and Wisconsin, a disease-free honeysuckle tree has been found in western North Carolina, almost the same elsewhere.