Cut-leaved Alder Imperialis A pretty tree for gardens with poor, wet soil, Alnus glutinosa Imperialis is a small to medium-sized, very slow-growing, deciduous tree with an elegant, slender, conical habit. The green leaves are particularly beautiful, deeply cut, giving a delicate, feathery effect, turning yellow in autumn. In early spring, purplish-brown male catkins dangle from the tree; the female flowers are insignificant, and are followed by little brown, cone-like fruits, attractive to birds. Alders are able to produce nitrogens from bacteria in nodules on their roots, and can tolerate wet soil. Alder Imperialis holds the RHS Award of Garden Merit. Site: Tolerates exposureSoil: Moist or wet soil, including fairly poor soils; dislikes chalky soilsPosition: Full sunSeason of interest: Spring to autumnHardiness: Very hardyHeight: 23’ (7m) Spread: 10’ (3m) in 20 years