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Pin Oak Quercus palustris


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Pin Oak, habit and fall color
credit: Raymond C. Martin, Jr./CCSA

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Family: Fagaceae, Beech view all from this family

Description Quercus palustris, also called Swamp Spanish oak, is a member of red oak section (Quercus sect. Lobatae). It is native to North America, mainly in the eastern United States from Connecticut west to eastern Kansas, and south to Georgia but not Florida, across to eastern Oklahoma; it is also native in the extreme south of Ontario, Canada.

It is a medium-sized deciduous tree growing to 100+ ft tall, with a trunk up to 1 m (3 ft) diameter. It has an 8-14 m (25-45 ft) spread. A 10-year-old tree will be about 8 m (25 ft) tall. The crown is broad conic when young, with numerous small branches radiating out from a central leader. When older, some upper branches become quite large and the central leader is lost, while the lower branches gradually droop downwards.

The leaves are 5-16 cm long and 5-12 cm broad, lobed, with five or seven lobes. Each lobe has 5-7 bristle-tipped teeth. The sinuses are typically u-shaped and extremely deep cut. In fact, there is approximately the same amount of sinus area 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. The acorns, borne in a shallow, thin cap, are hemispherical, 10-16 mm long and 9-15 mm broad, green maturing pale brown about 18 months after pollination. The acorn is unpalatable because the kernel is very bitter.

The species usually lives only 90 to 120 years. 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. The specific name palustris means "of swamps".

A characteristic shared by a few other oak species, and also some beeches and hornbeams, is the retention of leaves through the winter on juvenile tissue. Young trees under 6 m (20 ft) will often be covered with leaves year-round, though the leaves die in the fall, remaining attached to the shoots until the new leaves appear in the spring. As with many other oak species, dead pin oak branches will stay on the tree for many years.

The acorns are small with a thin, shallow cap.

The pin oak is in the red oak subgenus: pointed lobes.

The sinuses are very deeply cut and u-shaped.

The amount of sinus area is approximately equivalent to the amount of actual leaf area.

The upper branches point upwards, the middle branches are perpendicular to trunk, and the lower branches angle down.

Pin oak grows primarily on level or nearly level, poorly drained alluvial floodplain and river bottom soils with high clay content. Pin oak is usually found on sites that flood intermittently during the dormant season but do not ordinarily flood during the growing season. It does not grow on the lowest, most poorly drained sites that may be covered with standing water through much of the growing season. However, it does 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.

Habitat Scrub, shrub & brushlands, Watersides (fresh).

Range New England, Mid-Atlantic, Great Lakes, Plains, Southeast.

Comments One of the faster growing oaks. Tolerates wet feet. Intolerant of alkaline soils. Susceptible to iron chlorosis which causes yellow coloration in the leaves through the summer months and can eventually kill the tree. Somewhat tolerant of city conditions.

Exposure Preference Sun.

Native Distribution Georgia to Oklahoma, n. to Massachusetts, s. Ontario, s. Michigan, Illinois, Iowa & e. Kansas

Site Preference Wet woods; bottomlands

Soil Preference Heavy, poorly drained soils. pH 5.5-6.5.

Wildlife Value Attracts songbirds, water birds, ground birds and mammals.