leaf margins are very slightly toothed, especially near the apex. The seed cones are ovoid in shape and typically measure in length and in width. The scales are ovate to cuneate in shape and measure in length by in width. The apex is more or less rounded and is often projected outward. Twenty-four diploid chromosomes are present within the trees' DNA. Wood The wood is soft, coarse-grained, and light buff in color. Air-dried, weighs . The lumber is used for general construction and crates. Because of its unusual power of holding spikes, it is also used for railroad ties. Untreated, the wood is not durable if exposed to the elements. As a fuel, it is low in value. The wood is also a source of pulp for paper manufacturing. Distribution and habitat T. canadensis occurs at sea level in the north of its distribution, but is found primarily at elevations of . It ranges from northeastern Minnesota eastward through southern Quebec and into Nova Scotia, and south in the Appalachian Mountains to northern Georgia and Alabama. Disjunct populations occur in the Piedmont region, northern Alabama, western Ohio and into Indiana, as well as western Wisconsin and eastern Minnesota. In Canada, it is present in Ontario and all provinces to the east except Newfoundland and Labrador. Its range completely overlaps that of the closely related Tsuga caroliniana. It is found primarily on rocky ridges, ravines, and hillsides with relatively high levels of moisture. Climate Eastern hemlock is generally confined to areas with highland climates, with cool and humid conditions. Precipitation in the areas where it grows is typically to more than per year. The lower number is more typical of northern forests that receive heavy snowfall; the higher number is common in southerly areas with high summer rainfall. Near the Atlantic coast and in the southern Appalachians where the trees often reach their greatest heights, annual rainfall often exceeds . In the north of its range, the temperatures in January average , while in July they average only . In these areas, the frost-free season can last fewer than 80 days. In contrast, the southern end of the range experiences up to 200 days without frost and January temperatures as high as . Hemlock woolly adelgid The species is currently threatened by the hemlock woolly adelgid (Adelges tsugae), a sap-sucking bug introduced from East Asia to the United States in 1924,