The Native Trees of Colorado,
by S. K. Wier
revision of October 16, 2011
This web site for anyone who is interested in the trees of Colorado. My goal is to offer a guide to identification of Colorado native trees which is easy to use. There is considerably more detailed and particular help here for identifying Colorado trees than you will find in the national-scale tree guide books or in many regional guides. In fact many of those books omit some native trees of Colorado. I also describe something about the trees' habits and the role of the trees in the forests of Colorado. This guide describes every native tree of Colorado.
It is easy to learn to recognize the trees you will see. In one forest location in Colorado you will generally find only five or ten types of trees. There are only some fifty kinds of trees native to all of Colorado, or even less if you do not count those which often grow as large shrubs - low diversity for such a large forested region, some 25,000 square miles, with many habitats.
The easiest features to uniquely identify each tree are explained in detail here, with possible variations. Only the key features used to identify a tree are described. There is little botanical terminology to confuse the non-expert. The descriptions are for trees as they grow in Colorado, rather than for the same trees from other regions with different sizes and appearance. Also check my one-page "Instant Tree Finder," a one page guides for the conifers.
Trees are by far the largest and most numerous large living organisms in North America. Trees are key species in the enviroment in mountain forests and in the surrounding foothills, shrublands, plains, and deserts. They have an important influence on the ecosystems in which they live, and so help determine what other plants and animals can live there. Trees were essential in the early exploration and settlement of America by the native Indians and Europeans.
This guide will also serve for most of the trees of northern New Mexico, eastern Utah, the Black Hills, and much of Wyoming including Grand Teton and Yellowstone National Parks. The forest populations in those regions differ some from Colorado of course, but there is much in common. Those regions have a few kinds of trees not native to Colorado, such as the Whitebark pine and Black cottonwood in Yellowstone National Park, the White spruce and the Burr oak in the Black Hills, and the Arizona alder, gray oak, and alligator juniper in New Mexico.
This guide was started to meet a need I saw for a detailed description of all of the Colorado native trees. When I first worked on this, about 20 years ago, there were many fewer detailed guides for trees. I did not find guides like I needed, partly because I did not know where to look. Most of what was available was too simple, or too detailed, for professional botanists. Now there are a large number of fine books on regional natural history (see my list of books), For Colorado trees, I think this is still useful. And with the internet I can make it easily available.
Table of Contents
Southwestern White Pine
Distinguishing the Pines
The Broadleaf Trees
Canyon or Bigtooth Maple
The Small Broadleaf Trees and some large Woody Shrubs
New Mexico Locust
Single Leaf Ash
Willows: Narrowleaf, Scouler's, Bebb and others
Uncommon Colorado natives coming from adjacent states
Invasive non-native trees: Tamarisk and Russian Olive
Map of Colorado Forests (Colorado State Forest Service). Click for full size.
Instant Tree Finder Chart (conifers)
Books on Trees and Forests of Colorado
The Mountain Pine Beetle and the recent pine beetle epidemic.
Life Zones and Habitats of Colorado by Colorado Native Plant Society. For Life Zones and Habitats, scroll down to bottom of page.
Scientifc names are from the Catalog of the Colorado Flora: A Biodiversity Baseline, William A. Weber and Ronald C. Wittmann. University Press of Colorado, 1992. Electronic version, revised March 11, 2000: http://cumuseum.colorado.edu/Research/Botany/Databases/catalog.html, accessed September 16, 2011.
October 16, 2011 The Native Trees of Colorado: Text Copyright © 1998, 1999, 2002, 2010, 2011 S. K. Wier
Reproduction, retransmission, or redistribution prohibited without prior written consent of the author. Individuals are welcome to print one copy for their own personal use.