The grey alder is showing slender golden-tinted catkins at the junction of Middle Walk and South Walk.
Belonging to the Betulaceae (birch family) the genus Alnus numbers some 30 species of catkin-bearing deciduous trees and shrubs from the northern hemisphere. Members of the genus have alternate, toothed leaves and conspicuous male catkins, and smaller female catkins which develop into woody, cone-like fruits. Many of the species do well when grown beside water, including the grey alder, A. incana, which is broadly conical in habit, and can reach 20m in height. A. incana ‘Aurea’ is a rare selection with a more slender habit than the straight species. It has pale summer leaves which take on yellow hues, and orange-yellow shoots and catkins, from which it takes the name ‘Aurea’, meaning golden-yellow.