[1][2] He became interested in botany and undertook a detailed plant survey within a fifty-mile radius of his home, collecting seeds for his garden and building an extensive herbarium.
[1] Based on this effort, Walter completed a manuscript in 1787 containing a summary of all the flowering plant species found in the region.
It was the first comprehensive regional flora set in eastern North America and the first to use Linnaeus' binomial naming conventions.
Today, 88 of these species and one genus (Amsonia) still bear the valid names provided by Walter in his Flora.
His herbarium was taken to England by Fraser and eventually purchased by the British Museum of Natural History where it still exists.