Burr wood

BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries. A guide to the use of urban timber (FB 50) was written by Geoff Cooper and published by BRE on 31 July 2012.

The guide suggests that.

Burr is an irregular-shaped swelling or excrescence found most often on the lower main trunk, but also on branches and rootstocks of a range of tree species. A burr can take on several forms: it may consist of clusters of expanding slow-growing epicormic buds or be formed from a distinct series of irregular contorted swirls.

Birds-eye figure can be easily mistaken for the burr figure that is created by epicormic growth due to a similarity in appearance. However, birds-eye figure is caused by irregularities in the growth rings in the form of depressions or dimples which, once formed, are perpetuated through the stem. These elements run in various directions more or less at right angles to the stem surface. The irregularities of the growth rings will show on tangentially cut surfaces as (a) highly ornamental mass of circular ‘eyes’.

--BRE Group