"Near the river, which is named the Guoy, apples are found upon Ash trees in a sloping woodland [or pass], at the mouth of the river."1
These marvellous trees apparently grew somewhere near the mouth of the River Wye (the Gwy2). Marc Hampton has suggested, plausibly, that this is the True Service Tree*3, which does, indeed, have leaves like the related Mountain Ash, and bears Apple-like fruits (sorbs)4. In the past these have been used to make a cider-like drink*.
The tree still grows in this area5, but is rare. Notably, it seems that the tree is competed-out of normal woodland, and only thrives on very steep limestone slopes* where other trees have difficulties.
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