Windberry

On a nearer examination, he found this beautiful tint to arise from the young shoots of the common windberry (Vaccinium Myrtillus) which grows there in great abundance.

[…]and during the season of its appearance, the windberry pudding has a “prescriptive right” to take the lead at the forester's second course.

It is closely related to blueberries and huckleberries. Windberries are used fresh or in confections, jams and pies.