Meet the Trees: Pin Oak, The Most Important Plant
Quercus palustris or the pin oak is a common oak in the Madison Square Park Urban forest. The pin oak is native to New York City where its range extends south and west along the Mississippi River Basin. This range comprises much of the regional alluvial flood plain and glacial till plain where snow melt is common and glaciers left soil deposits during the last ice age. Because these areas are excessively wet in spring and winter, these trees have adapted to survive flooding during dormancy. Unlike many oaks that have a persistent tap root, pin oaks develop a more fibrous root system that allows them to establish in poor clay soils and to tolerate wet soils. This adaptation allows pin oaks to easily be grown in containers, a challenge for many other oak species. The pin oak has been introduced abroad to Australia, South Africa and Argentina where it thrives in areas that experience periodic floods.
Pin oaks have a very distinctive canopy. The upper branches point upwards and the lower branches droop downwards making them easy to distinguish between other oaks based on habit alone. Young trees often retain their dead leaves throughout the winter, a phenomenon known as marcescence. Scientists are not sure why many oaks exhibit this phenomenon but some theories suggest that the leaves help protect trees from water and temperature stress. Others suggest that these trees hold on to their leaves longer to keep them available for mulch. Many trees including oak that exhibit marcescens have leaves that do not readily decompose in cold temperatures. By holding their leaves until spring, these trees can take advantage of spring decomposing insects who are more likely to create mulch directly under their canopy.
Oaks are the most important plant you can plant for wildlife worldwide. 521 species of caterpillar require oak as part of their diet and 14 bird groups that visit the Park depend on some part of the oak to complete their life cycle. These Park staples generally live for about 120 years and only thrive in bright sunlight. Oaks can commonly be found around the Park perimeters where more light is available. The Pin Oaks demand for sunlight is a challenge for planting successive oaks at Madison Square Park because older specimens will need to create gaps in the canopy to allow adequate light before new specimens are planted.