Willow oak is also planted extensively as a street tree in New York City and it is sometimes difficult to distinguish native trees from those that were planted.
There are five existing native populations, but except for one population of tens of trees, there are only a few trees in the other populations. There is one historical population on Long Island and one on Staten Island, but there are also many planted trees around the New York City area.
All of the existing populations are small and could be eliminated at any time since none are protected, but currently they seem stable.
This tree was always very rare in New York because of climatic conditions and the number of natural populations has remained very small over time. There are many trees in the New York City area because they have been planted as landscaping trees but are not considered natural populations.
Most populations are threatened by the development of the surrounding habitat by roadwork or residential areas. Increased fragmentation would cause more hybridization with the more abundant red oak.
A natural buffer should be established around natural populations and cutting of trees should be prevented.
Genetic work could be done on existing natural populations to see if they are from local genetic stock or actually progeny from introduced trees.
In New York, Willow Oak has been found in floodplain forests, maritime grasslands, and roadside forests and woodlands (New York Natural Heritage Program 2010). Of bottomland flood plains, also on stream banks, dunes, and terraces, and, occasionally, on poorly drained uplands, from 0 to 400 meters in elevation (FNA 1997). Swamps and moist soil (Gleason & Cronquist 1991). Swamps, bottoms and other low ground, or sandy uplands (Fernald 1970).
This oak is known from a few native localities on Staten Island and Long Island except Nassau County. It is considered extirpated in Suffolk County.
This is a tree of the South-Central and Southeastern United States extending north to Southern Illinois where it is rare and to Eastern Pennsylvania and Long Island where it is also rare. It does not extend south into the peninsula of Florida.
Willow oak is a long-lived overstory tree, growing up to 30m tall. It has tight, gray to blackish bark. The twigs are reddish brown and glabrous, with mature buds also glabrous, ovoid, pointed, and 2 to 4 mm long. The leaves are linear to narrowly elliptic, entire except for a single bristle-tip, generally 1 to 2 centimeters wide, and glabrous or nearly so, and deciduous in autumn. The fruit (acorns) are 1 to 1.5 cm long, 1/4 to 1/2 covered by the light brown, saucer-shaped, pubescent cap (Rhoads and Block 2000, FNA 1997).
Willow oak can be identified, in the appropriate season, from the seedling stage throughout its maturity.
Willow oak's distinct narrow, unlobed, bristle-tipped leaves are unique among New York oak species.
Willow Oak may be identified whenever the leaves are out.
The time of year you would expect to find Willow Oak vegetative and fruiting in New York.
Quercus phellos L.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Flora of North America Editorial Committee. 1997. Flora of North America north of Mexico. Vol. 3. Magnoliophyta: Magnoliidae and Hamamelidae. Oxford Univ. Press, New York. xxiii + 590 pp.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
Little, E.L., Jr. 1979. Checklist of United States trees (native and naturalized). Agriculture Handbook No. 541. U.S. Forest Service, Washington, D.C. 375 pp.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.
Rhoads, Ann F. and Timothy A. Block. 2005. Trees of Pennsylvania. A Complete Reference Guide. University of Pennsylvania Press, Philadelphia, PA.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Information for this guide was last updated on: February 28, 2011
Please cite this page as:
New York Natural Heritage Program. 2023. Online Conservation Guide for Quercus phellos. Available from: https://guides.nynhp.org/willow-oak/. Accessed June 5, 2023.