Soapberry
A soapberry tree in bloom. (Photo by Cathryn Hoyt)
Soapberries can be used to make a soapy lather. (Photo by Cathryn Hoyt)
Soapberry trees are the main source of nectar for this soapberry hairstreak. (Photo by Cathryn Hoyt)
By Kay Wilde
The Chihuahuan Desert region has plenty of wide open spaces, cacti, grasses and shrubs. But trees, which usually require more rainfall, seem relatively rare. A few manage to take hold in the harshest desert landscapes though, and one of these can even be used to wash your hands. What is this tenacious tree? And how has it been used by desert dwellers?
The hardy soapberry tree is found across Texas and throughout the Chihuahuan Desert. In our region, it’s relatively short, but it can grow to forty feet with adequate water and space. You’ll often find soapberry trees growing in thick groves on the banks of creeks and arroyos.
Soapberry trees are able to form such groves because of how they can propagate themselves. The tree sends out long underground stems, called rhizomes, from which more trees sprout. So when you see a thicket of soapberry trees, you’re often looking at clones of the same tree. Aspens multiply this way too.
In spring, soapberry trees bloom with clusters of creamy white flowers, which drop off for about three weeks in late summer or fall. In their place grow tough-skinned, marble-sized fruits with translucent amber flesh and a large black seed. Though it’s called soapberry, botanists actually call these kinds of fruits drupes. Peaches, cherries, mangoes and olives are also drupes.
Soapberry gets its name from toxic chemical compounds in the drupes, called saponins, which produce a frothy soap. To make these suds, just take a soapberry and rub it in your hands with a little water. Be careful though; some people are sensitive to saponins and may get contact dermatitis.
People in the desert southwest have made laundry detergent and shampoo from soapberry fruits, and in parts of rural Mexico, some still rely on this natural source of soap. In his book Remarkable Plants of Texas, Matt Warnock Turner reported that washing with this lather “left his hands surprisingly clean, supple and smooth.” In Asia, the fruits of related trees are used to wash delicate silk and in medicinal cleansers.
Soapberry has had medicinal applications closer to home as well. Folk traditions here turned to the fruits as a fever remedy and to treat rheumatism and kidney disorders. Kiowa tribes cut into the stems for latex, which they applied to their wounds.
But beware: saponins are considered poisonous, and ingesting soapberry fruits will probably leave you with a very upset stomach. Villagers in Mexico took advantage of this toxicity by throwing soapberry fruits into streams and ponds to stupefy fish, making them easier to catch.
People have found other uses for soapberry. At one time, the wood was cut for ax handles and packsaddle frames and sliced into strips for weaving baskets. The dark seeds were made into beads, jewelry and buttons. And the pulp has even been used to manufacture floor wax.
But humans are not the only desert dwellers who exploit soapberry. Cedar waxwings, bluebirds and robins favor its fruit. And the life of the soapberry hairstreak revolves around it. The caterpillars of this delicately marked, chocolate-colored butterfly only eat leaves from soapberry trees. Then they time their emergence as adults when soapberry blooms. Although the flowers are not very showy to us, they are this butterfly’s main source of nectar.
If you hike in the desert, the penetrating sunshine and dry air will probably have their effect on you. You will then really appreciate finding a soapberry tree, where you can rest and cool off in precious shade. This may be what you treasure most among the soapberry tree’s many virtues.
Volunteer contributor Kay Wilde is a writer and Texas Master Naturalist in Alpine.
Have a question or comment about this episode? Contact Nature Notes Coordinator Megan Wilde at mwilde [at] cdri [dot] org. Or discuss this episode on Nature Notes’ Facebook page.
References & Resources for Educators
- Remarkable Plants of Texas: Uncommon Accounts of Our Common Natives by Matt Warnock Turner (University of Texas Press, 2009)
- Edible and Useful Plants of Texas and the Southwest by Delena Tull (University of Texas Press, 1999)
- Western Soapberry: Lady Bird Johnson Wildflower Center’s Native Plant Database
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Nature Notes is sponsored by the Meadows Foundation and the Dixon Water Foundation and is produced in cooperation with Marfa Public Radio.
