Betula pendula var. carelica

Curly birch (Betula pendula var. carelica) is a variant of the plant species silver birch (also known as warty birch, European white birch, or East Asian white birch) with a genetic defect that causes the tree to twist on the stem with curls. The annual rings are oriented incorrectly, which gives the wood a fiery appearance. The variant originally comes from Karelia in Finland and Russia. The curliness is passed on in up to 70% of all trees in the next generation. Common spring birch is also sometimes referred to as masonry birch, but one should only use that term for trees that have the real curliness....read more on Wikipedia.