Sumac Family Primer for the San Gabriel Mountains


Common and widespread, plants in the sumac family typify our image of southern California hillsides, particularly in the San Gabriel Mountains on the coastal side of the Front Range. Sometimes, in winter, they are the only green plants you see. The sumac family includes large, rounded shrubs, with simple, aromatic, evergreen leaves and smaller, thicket-like shrubs with deciduous and three-parted leaves. A non-native species, the familiar pepper tree, has naturalized around old homesteads.

The sap of the plants in the sumac family is resinous, sometimes milky. All contain skin irritating compounds to a greater or lesser degree. The infamous and irritating poison oak belongs to this family.

The flowers are very small and come in parts of five. They are borne in clusters at the ends of branches or sometimes between branches. The fruit also comes in clusters like small bunches of grapes and is berry-like with a single, hard seed in the middle surrounded by flesh that may be tart. The leaves are alternate.

The number of records is an rough indicator of frequency. You are almost sure to see those with the largest number of observation records.


1. Are the shrubs, large and rounded, and the leaves, simple (not divided into smaller leaflets) and evergreen (not dropping off in winter)? 3. Are the plants treelike with evergreen, drooping, compound leaves having about 15 leaflets? 4. Are there three leaflets and a stalk on the middle terminal leaflet?


Malosma laurina, Rhus laurina

Rhus integrifolia

Rhus ovata

Rhus trilobata

Schinus molle

Toxicodendron diversilobum, Rhus diversilobum

Sources and Other Web Information

CalFlora Occurrence Database Observation records for the San Gabriel Mountains.

Current Bug, Snake and Varmint Reports in the San Gabriel Mountains: Other Pests

Family Secret Cashew (sumac) family members have an unpleasant chemical in common. From the Orange County Register

Let's Talk about "Poison Oak" From Palo Alto Troop 5...Pacific Skyline Council...Boy Scouts of America

Online Key to Local Species has more information on the differences between poison oak and squawbush

A California Flora by Philip A. Munz. University of California Press, 1968.

Flowering Plants, the Santa Monica Mountains, Coastal and Chaparral Regions of Southern California by Nancy Dale. Capra Press, 1986.

The Jepson Manual Higher Plants of California edited by James C. Hickman. University of California Press, 1993.

Native Shrubs of Southern California by Peter H. Raven. University of California Press, 1966.

A Natural History of California by Allan A. Schoenherr. University of California Press, 1995.

Roadside Plants of Southern California by Thomas J. Belzer. Mountain Press Publishing Company, 1984.

Sierra Nevada Natural History by Tracy I. Storer and Robert L. Usinger. University of California Press, 1963.

Go to: Keys to Identifying Selected Plant Groups in the SGM

Copyright © 2000 by Jane Strong and Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Jane Strong | Tom Chester
Updated May 6, 2000.