of B. lutea and B. alleghaniensis, Merritt Fernald found the latter to be identical to B. lutea, but did confirm the existence of two varieties. Later, the name Betula lutea was determined illegitimate as it was superfluous to the older name that Michaux had listed as a synonym, Betula excelsa Aiton (1789). Additionally, the type specimen of Betula excelsa was found not to be a yellow birch, making Betula alleghaniensis the oldest and correct replacement name for the illegitimate B. lutea. The specific epithet alleghaniensis means "of the Allegheny Mountains". In addition to "yellow" or "golden" birch, B. alleghaniensis has also been called gray birch, silver birch, tall birch, and swamp birch, though it shares several of these names with other Betula species. Varieties Several varieties have been named, but are not recognized as distinct by modern authors: B. a. var. alleghaniensis — scales on the fruiting catkins 5–8 mm B. a. var. macrolepis (Fernald) Brayshaw — scales on the fruiting catkins which measure 8–13 mm B. a. var. fallax (Fassett) Brayshaw — dark brown bark that typically does not exfoliate into shreds or curly flakes at the surface, especially noticeable when the bark is wet Hybrids It hybridizes with Betula pumila to form Betula × purpusii in larch swamps. These hybrids are rather common and shrubby in growth pattern and may have an odor of wintergreen or rusty-hairy twigs. The leaf shape is intermediate between both species. It can also hybridize with Betula papyrifera in northern regions where their ranges overlap. It has seldom been reported but is thought to be more common than realized. In most features it is intermediate between the two parents. Range and climate Its native range extends from Newfoundland to Prince Edward Island, Nova Scotia, New Brunswick, southern Quebec and Ontario, and the southeast corner of Manitoba in Canada, west to Minnesota, and south in the Appalachian Mountains to northern Georgia. While its range extends as far south as Georgia, it is most abundant in the northern part of its range. In southern Pennsylvania, it is rare and generally only found along bodies of water in cool, mature woods, and it only occurs at high elevations from Maryland southward. It grows in USDA zones 3-7. B. alleghaniensis prefers to grow in cooler conditions and is often found on north facing slopes, swamps, stream banks, and rich woods. It does not grow well in dry