The northern limit of the natural distribution of Tilia cordata in Britain is the English Lake District (latitude 54° 30′N). Many populations contain very old trees and in all but three of 150 localities there has been no regeneration from seed for at least a century. Seeds produced are largely infertile. Trees commonly grow in rocky situations which have probably never been entirely cleared by man. Most localities are between sea-level and 160 m, sometimes on level ground but usually on slopes with aspects between 45° and 315°. Populations occur on all the main rock-types and on soils ranging from acid rankers and brown podzolic soils to rendzinas. The climate of the region is characterized by mild winters and cool summers with mean daily maxima of air temperature for July and August not exceeding 19°C.