A notoriously variable species, identification complicated by varying leaf-underside hairiness. Relatively uncommon in north-west Europe, mostly limited to ornamental planting. Known as American Basswood in North America. Introduced 1752.

Native to North America, including central and eastern Canada, eastern USA, and Mexico. Initial collections proved ill-suited; northern sources performing better in north-west Europe, particularly the cooler climes of Britain and Ireland.

Monoecious. Insect-pollinated. Wind-dispersed.

Large (30m or more), conical. Bark brown-grey, maturing with irregular fissures. Twigs often densely hairy, sometimes glabrous; buds alternate, variably downy, with 2(-3) visible scales. Leaves large (15cm), ovate or rounded, dark green above, often densely downy with vein-axil tufts below, regularly sharp-toothed, on a long (20-60mm) petiole. Flowers in a 2-4-branched pendulous cyme of 9-24 yellow-green blooms. Fruits globose or ellipsoid (5-10mm), densely downy without a prominent rib, with a papery bract.