Samuel Wells Williams was a well-known missionary, diplomat and sinologist. In his whole life, he never gave up his pursuit on botany, however, there was not much attention to his botanical accomplishment. Williams had a lifelong friendship with Asa Gray, who was the most distinguished American botanist in the 19th century. And because of the contact, Williams related with botany indeed. In order to figure out their friendship and influence, this article is going to use the correspondences between Williams and Gray, besides the related publications. This article first presents Williams\u27 lifelong friendship with Gray, then, accounts for the plants and seeds which Williams gave to Gray. Finally, it will demonstrate the influence of Gray towards Williams\u27 contact with Ko Kun-hua, who was the first professor of Chinese descent at Harvard University.氏名の表記に一部誤記がありましたので訂正していま
