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Weed Alert!

Schinus polygamus (Cav.) Cabrera
(Peruvian peppertree)

Summary: new plant of unknown characters
Native to South America, Schinus polygamus is a spiny, nondescript plant that was once commonly cultivated in California as an ornamental. Even though it is now rarely used as an ornamental, specimens have persisted in abandoned groves, margins of disturbed or cultivated areas, and in slightly moist sites. Like other species in its genus, this plant is demonstrating invasive characteristics. Staff of the botanical garden at the University of California, Riverside consider it one of their worst woody weeds. At present, S. polygamus has been reported from Los Angeles, Riverside, and San Bernardino counties. However, its range is expanding. This plant has the potential to spread to the coast, and then up towards the northern parts of the state.

(Click on thumbnail images for a closer view)

Tree branch


Branch spine

Bolting shoot

Schinus polygamus (Anacardiaceae -- the sumac family) is a slow growing spiny shrub when young, but can mature into a dense, rounded, or twiggy tree up to 9 m tall. The simple leaves are evergreen, leathery, and may be fragrant. The leaf dimensions are variable, but average 6 cm long and 2 cm wide. The leaf is narrowly elliptical or slightly obovate, and the leaf edges do not have teeth. The tree can have both unisexual and bisexual flowers, but a given tree is normally male or female. Flowers are produced in late spring and are small, greenish-white, and abundant. The berries are dull and greyish-purple to black.

Scientific and Common Names:
The genus name, Schinus, is derived from Greek schinos used to describe the mastic tree, Pistacia lenticus, which has similar resin. The species epithet, polygamus, is derived from polygamous, meaning with both single and dual sex flowers on one or different plants. Synonyms for S. polygamus include "Amyris polygama Cav.", "Schinus dependens Ortega", and "S. dependens var. longifolia Fenzl. ex Engler in Martius". The common name, peppertree, is given to the trees in this genus because the seeds were used to adulterate pepper. As its common name implies, this plant occurs in Peru as a native.

Impacts and Considerations:
The impacts of this new invader are unknown. However, the related plants Schinus molle and S. terebinthifolius are well known to be weedy in wildland areas. S. terebinthifolius displaces natives and alters soil composition, and is considered one of the worst weeds in southern Florida. S. molle potentially alters structure and composition in grasslands, woodlands and coastal scrub areas.

The fruit of S. molle and S. terebinthifolius are disseminated by birds. It is likely that the fruit of S. polygamus can be spread in the same manner.

Native Range:
Schinus polygamus is native to Chile, Argentina, Brazil, Uruguay and Peru.

Range As An Invader:
Schinus polygamus may become problematic in northern California and in moister areas near the coast. It has not invaded the drier hillsides near Riverside. S. polygamus appears less adapted to aridity than S. molle. However, Jacobson (1996) reports that it tolerates heat, drought, and frost.

Little information is available on the control of Schinus polygamus. Much of the control suggestions below are extrapolations of methods shown to be effective on the closely related plants Schinus molle and Schinus terebinthifolius.
1) Small S. polygamus plants can be dug or grubbed out (6). If hand pulling, the use of gloves is recommended because of number of species in this family can cause contact dermatitis.
2) Painted stump application with glyphosate concentrate is effective (6). Small plants (3 cm basal diameter) can be cut at ground level. Control of larger plants is said to be more effective if the trunk is cut slightly below ground level. This would be time consuming with large plants, so it might be more efficient to accept the decreased effectiveness of conventional painted stump methods, but treat many more plants. A 2% glyphosate mix can be sprayed on resprout foliage to increase efficacy.
3) Control of S. terebinthifolius with Garlon 3A (50% concentration) and Garlon 4 (10% concentration) has been successful in Florida using the cut stump method with Garlon 3A and basal bark application method with Garlon 4.
4) A Chilean study found that S. polygamus leaves and fruit were palatable to sheep (4).

1) Diggs, Jr., G.M., Lipscomb, B.L., and O'Kennon, R.J. 1999. Anacardiaceae In: Shinners & Mahler's Flora of North Central Texas. Botanical Research Institute of Texas and Austin College, Texas, USA. p. 530.
2) Jacobson, A.L. 1996. Schinus in: North American Landscape Trees. Ten Speed Press, Berkeley, C.A. pp. 589-590.
3) Sanders, A.C. 1996. Noteworthy Collections: California. Madrono 43(4):530.
4) Torres, B.A., Avendano, R.J., Ovalle, M.C., and Paladines, M.O. 1987. Sheep stocking rates on subhumid Mediterranean range in Chile. 4. Food intake and selectivity. Agricultura Tecnica 47(4):313-320.
5) http://mobot.mobot.org/Pick/Search/pick.html
6) Morgan, S. 2000, University of California, Riverside, private communication.

--Tunyalee Martin/Wildland Invasive Species Team; July 2000

Updated January 2005
©The Nature Conservancy, 2000