Quercus bicolor aka Swamp White Oak

Swamp white oak, Quercus bicolor, is a deciduous tree in the beech family, Fagaceae. It grows wild from south-eastern Canada through the central and eastern United States. Its range reaches Ontario and Quebec in the north and Georgia and Arkansas in the south. In the wild it favours low, damp ground. Look for it on floodplains, in valleys, along streams and lakes, and at swamp margins.

In gardens it reaches 50 to 60 feet (15 to 18 m) tall, with a similar spread. Some trees grow larger, and wild specimens can top 75 to 80 feet (23 to 24 m). Young trees have a pyramidal outline. With age they develop a broad, rounded crown on a short trunk, and the lower limbs often persist. Growth is moderate, and a tree can live for about 300 years.

The name bicolor refers to the two-toned leaves. They are glossy dark green on top and felted, silvery white below, so they flash pale in the wind. Each leaf is 3 to 7 inches long and widest toward the tip. Its edge carries shallow, rounded lobes or coarse teeth. Autumn colour varies from yellow to copper, orange or reddish purple. Young bark is smooth. Older bark turns dark grey-brown, thick and deeply furrowed, and it flakes and peels. The peeling bark on the branches is a good field mark.

Flowers appear in spring, mostly around April. Male flowers hang in yellow-green catkins 2 to 4 inches long. Female flowers form short green to reddish spikes. The wind carries the pollen. The brown acorns ripen in September and October. They sit on unusually long stalks, often in pairs, and a scaly cap covers a third to half of each nut. Heavy crops come every three to five years.

Give this oak full sun or light shade and moist to wet, acidic soil. It copes with spring flooding and dry summers, and it tolerates some drought and city conditions. Compacted soil, salt and air pollution cause it trouble. Leaves may yellow between the veins if the soil is too alkaline. Young trees can be hard to move and slow to settle. It is hardy in USDA zones 3 to 8 and rated H6 in the UK. Use it as a shade, lawn or street tree, or near ponds and in rain gardens. Woodpeckers, jays, turkeys, deer, bears and small mammals eat the acorns. The leaves feed the caterpillars of many moths and hairstreak butterflies.

Many pests and diseases can attack it, though few cause serious harm. Problems include anthracnose, cankers, leaf spots, rust, blight and powdery mildew. Insect pests include borers, leaf miners, oak lace bugs, mites and various caterpillars. Oak wilt is a real threat to this species. Raw acorns contain tannins that can upset the stomach and harm pets. Once you leach or boil out the tannins, the acorns are edible. Native peoples and settlers ate them, and roasted acorns served as a coffee substitute. The inner bark once supplied tannin for leather and a yellow dye.