Tree Guide

This guide initially displays common trees of all shapes. Use the selectors below to view particular shapes, include rare species, or search by name.

Growth of trees in the Southwest largely depends on temperature and moisture. In general, temperature is lower at higher altitudes, moisture is greater. As altitude affects temperature and moisture, it largely determines the distribution of tree species in this area.

Los Alamos County and surrounding areas include three main vegetation zones. The Pinyon-Juniper Woodland (4500 – 7500 ft; 1375 – 2300 m) is characterized by pinyon pine, one-seed juniper, alligator juniper and Rocky Mountain juniper. The Ponderosa Pine Forest (5500 – 8500 ft; 1700 – 2600 m) consists mainly of ponderosa pine. The Spruce-Fir Forest (8000 – 12000 ft; 2500 – 3650 m) includes Douglas fir, white fir, quaking aspen, limber pine, and, at higher altitudes, Engelmann spruce and subalpine fir. Little (Southwestern Trees: A Guide to Native Species in New Mexico and Arizona [PDF]) describes these zones in more detail.

Two recent catastrophic wildfires (Cerro Grande Fire in 2000, Las Conchas Fire in 2011) burned large areas of Los Alamos County. The burned areas now support fast-growing pioneer species rather than the slow-growing trees that characterize the vegetation zones. What was Pinyon-Juniper Woodland is now largely grassland; what was Ponderosa Pine Forest is now largely grass, Gambel oak, and quaking aspen; what was Spruce-Fir Forest is now largely grass and quaking aspen. Vegetation in these areas will change as succession proceeds.

This guide describes many of the native species of trees in and around Los Alamos County. It also includes a few introduced species that are often seen in the wild. More detailed information can be found in Plants of the Jemez Mountains Volume 1, which is available in the PEEC gift shop.

Tree References

American Trees – Big Trees Project
Arbor Day Foundation
Kershner, B, Mathews, D, Nelson, G, Spellenberg, R, 2008
National Wildlife Federation Field Guide to Trees of North America.
Sterling Publishing Company
Sibley. D.A., 2009 The Sibley Guide to Trees. Alfred A. Knopf, Inc.
Flora of North America
Encyclopedia of Life
Lady Bird Johnson Wildflower Center
Spellenberg, R., Earle, C.J., Nelson, G., 2014 Trees of Western North America.
Princeton University Press
Southwestern Trees: A Guide to Native Species in New Mexico and Arizona, 1968
Agriculture Handbook No. 9, United States Department of Agriculture [PDF]
Foxx, T., Martin, C., and Hoard, D., 2016 Plants of the Jemez Mountains Volume 1:
Tree, Shrubs, Vines, Ferns, and Horsetails.
All Seasons Publishing
US Department of Agriculture National Resources Conservation Services

Subject Area Experts (all guides)

Steve Cary (butterflies)
Beth Cortright (insects)
Terry Foxx (invasive plants)
Leslie Hansen (mammals)
Richard Hansen (fish, mammals)
Dorothy Hoard (butterflies, trees)
Chick Keller (flowers, herbarium)
Shari Kelley (geology)
Kirt Kempter (geology)
Garth Tietjen (reptiles)
David Yeamans (birds)

Web Development and Content Management

Pat Bacha
Jennifer Macke
Graham Mark
Akkana Peck


Please contact us for local nature questions and sightings. We welcome comments, corrections, and additions to our guides.

For more information about local nature, please visit our Nature Blog or subscribe to PEEC This Week.

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Showing 1 of 34 trees.
New Mexican Locust

Photo: Charlie McDonald - USDA Forest Service

New Mexican Locust

Photo: Chick Keller

New Mexican Locust, Mescal Bean

RONE (Robinia neomexicana)

Family: Fabaceae (Peas)
Size: up to 25 ft (10 m)
Growth: shrub, tree; perennial

Status: native; common
Habitat: deserts, mesa, canyons, and conifer forests at elevations of 4,500 to 8,000 ft (1,200 to 2,600 m)

Spiny shrub or small tree that often forms thickets. The bark is slightly gray with furrowed scaly ridges. Showy flowers appear in spring and early summer in large, drooping clusters. The fruits are brown bean-like pods with bristles. It is among the first woody plants to grow after wildfires but is soon shaded out by taller trees. Like many members of the pea family, New Mexico Locust has a symbiotic relationship with nitrogen-fixing bacteria that live in nodules in the plant’s roots.

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