I took my copy when I went to New Place in April. There, my guide at the Shakespeare Birthplace Trust confirmed he was an expert amateur botanist. They even had a copy of Gerard's Herbal on display at the time to illustrate the texts he studied.
John Hall, Shakespeare's son-in-law, was a physician and his garden at Hall's Croft is filled with the plants he would have used in his remedies. Perhaps his knowledge also enhanced Shakespeare's, as they were known to be close. I look forward to viewing this garden alongside my Botanical Shakespeare when I return to Stratford later this year.
For those of you who aren't members of the Herb Society, you can read the pdf version of my review here.