Quercus palustris

Quercus palustris, the pin oak or swamp Spanish oak, is an oak in the red oak section (Quercus sect. Lobatae). Pin oak is one of the most commonly used landscaping oaks in its native range due to its ease of transplant, relatively fast growth, and pollution tolerance. Its distinctive shape is considered unique among hardwoods. Q. palustris is mainly distributed in the eastern and central United States from Connecticut west to eastern Kansas, and south to Georgia, west to eastern Oklahoma and Kansas. It is also native in the extreme south of Ontario, Canada. The pin oak is also well adapted to life in Australia (where it has been introduced), and is quite widespread across the Australian continent, especially in the cooler southern States such as Victoria and New South Wales. It is also well adapted to life in South Africa and Argentina, especially in the Río de la Plata region. Pin oaks grow primarily on level or nearly level, poorly drained, alluvial floodplain and river-bottom soils with high clay content. They are usually found on sites that flood intermittently during the dormant season, but do not ordinarily flood during the growing season. They do not grow on the lowest, most poorly drained sites that may be covered with standing water through much of the growing season. However, they do grow extensively on poorly drained upland 'pin oak flats' on the glacial till plains of southwestern Ohio, southern Illinois and Indiana, and northern Missouri. The level topography and presence of a claypan in the soil of these areas cause these sites to be excessively wet in winter and spring. Pin oak is a medium-sized deciduous tree growing to 18–22 m (59–72 ft) tall, with a trunk up to 1 m (3.3 ft) diameter. It has an 8–14 m (26–46 ft) spread. A 10-year-old tree grown in full sun will be about 8 m (26 ft) tall. Young trees have a straight, columnar trunk with smooth bark and a pyramidal canopy. By the time the tree is 40 years old, it develops more rough bark with a loose, spreading canopy. This canopy is considered one of the most distinctive features of the pin oak: the upper branches point upwards, the middle branches are at right angles to the trunk, and the lower branches droop downwards. The leaves are 5–16 cm (2–6 1⁄4 in) long and 5–12 cm (2–4 3⁄4 in) broad, lobed, with five or seven lobes. Each lobe has five to seven bristle-tipped teeth. The sinuses are typically u-shaped and extremely deep cut. In fact, roughly the same amount of sinus area exists as actual leaf area. The leaf is mostly hairless, except for a very characteristic tuft of pale orange-brown down on the lower surface where each lobe vein joins the central vein. Overall autumn leaf coloration is generally bronze, though individual leaves may be red for a time, and is not considered particularly distinctive. The acorns, borne in a shallow, thin cap, are hemispherical, 10–16 mm (13⁄32–5⁄8 in) long and 9–15 mm (11⁄32–19⁄32 in) broad, green maturing pale brown about 18 months after pollination. The acorn is unpalatable because the kernel is very bitter. A fast-growing pioneer or riparian species, pin oak is relatively short-lived, with a maximum lifespan of 120 years against many oaks which can live several centuries. It is naturally a wetland tree, and develops a shallow, fibrous root system, unlike many oaks, which have a strong, deep taproot when young. It is confined to acidic soils, and does not tolerate limestone or sandy Florida soil, and grows at low altitudes from sea level up to 350 m (1,148 ft). The Latin specific epithet palustris means 'of swamps'.