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Western soapberry (Sapindus saponaria L. var. drummondii (Hook. & Arn.) L. D.
Benson) is a member of the Sapindaceae, which has approximately1450 species worldwide and
is mainly tropical in distribution. The genus name translates to “soap of the Indian” because of
the Native American use of the fruit for making soap. The species name also refers to soap and
the variety (a taxonomic dividing up of a variable species) is in honor of Thomas Drummond, a
Scottish botanist. The species was named by Linnaues (L.) and the varieties were first named by
two botanists (Hook. & Arn.) but this was later changed by L. D, Benson as he discovered new
evidence for dividing up the species. Anytime one sees parentheses in an authority, it indicates
that those original taxonomists have had their scientific work changed by the botanist outside the
parentheses. Enough about taxonomy and taxonomists!
Western soapberry is a small tree, usually up to 10 m, that I find growing in groups
within river bottomlands (See top photograph), although it can also occur on forest margins or at
disturbed sites. It occurs in small clusters or groves because it has underground stems called
rhizomes that produce new stems that grow into trees. It has compound leaves (middle
photograph), and small white flowers with the male ones containing 8-10 stamens (bottom
photograph). It is dioecious with male and female flowers occurring on separate trees. The
female flowers, upon pollination and fertilization, develop the globose, amber or yellow,
translucent fruits for which the plant is named. The fruits contain chemicals called saponins that
foam and remove dirt from surfaces and have been used as a soap substitute. However, they are
also considered poisonous and can cause contact dermatitis in some individuals when handling
the fruits. The crushed fruits have been used to poison fish by native peoples harvesting fish.
The Kiowas cut the stems and harvested the liquid that oozes out called latex and used it
to treat wounds. The round, shiny, black seeds under the saponin-containing flesh were used as
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beads by Native Americans. Other than fuel, the wood was used but little in minor applications
such as stakes and coarse baskets. The fruits are also the source of a yellow dye.
In the ecosystem, the fruits are eaten by many birds including bluebirds, cedar waxwings,
and robins. The fruits are eaten by few other animals and the flower nectar is believed to be
poisonous. Its rhizomatous growth and groves may help stabilize bottomland soils near the river
edge.
Sources:
Cox, P., & P. Leslie. 1988 Texas Trees: A Friendly Guide. Corona Publishing Company.
San Antonio, Texas.
Diggs, G. M., B. L. Lipscomb, & R. J. O’Kennon. 1999. Shinners & Mahler’s
Illustrated Flora of North Central Texas. Botanical Research Institute of Texas. Fort Worth,
Texas.
Simpson, B. F. 1988. A Field Guide to Texas Trees. Gulf Publishing Company.
Houston, Texas.
Tull, D. 2013. Edible and useful plants of the southwest: TX, NM and AZ. Austin:
University of Texas Press.
Turner, M. W. 2009. Remarkable Plants of Texas: Uncommon Accounts of Our
Common Natives. University of Texas Press. Austin, Texas.
Wrede, J. 2010. Trees, Shrubs, and Vines of the Texas Hill Country. Texas A&M
University Press. College Station, Texas.
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