I saw these in the NP Hoge Veluwe and thought WOW! how on earth did this happen? I thought it was natural.
But I was looking through a book my husband bought about the Sculpture garden in the NPHV and there were these tree's. Although they aren't anywhere near the garden they are actually a bit of art!
The Dennenwal (Pine wall) was created by Sjoerd Buisman in 1985. The pines are in a line that run 55m and were planted at a 45° angle on either side of a yoke, the tips of the tree's leaning against the yoke at a height of just under 2m. As a result the growth process has corrected itself from the yolk in a vertical manner. This started immediately after planting and continued to grow vertically at an angle so that over the years a twist in the bare root stock becomes visible.