Curly birch (Betula pendula var. carelica)
The first thing to say is that Curly birch is not a particular species of the birch tree. Curly birch is a variant of silver birch. It originates from Karelia in Finland and Russia, and is also known as Karelian birch.
It was once thought that the distinctive pattern was caused by beetle larvae boring into the tree, but it has now been shown to be a genetic anomaly (we prefer to use anomaly rather than defect - Mother Nature knows what she is doing!). The annual rings are oriented incorrectly, which gives the characteristic "flames" of the curly birch grain.
Beautiful, we're sure you agree, but this is no fragile beauty. In Scandinavia, Curly birch has been used to make knife handles since ancient times. Not because it looks nice (although this is important too) but because it is a very durable material.
Cared for in the proper manner, a Curly birch-handled knife will last for a very long time - passed from one generation to another.