By Canopy Team on July 23, 2018
Tree Spotlight Series: Follow along in this series as we learn about the fascinating trees that live among us. This series is in partnership with Rhee Lab in the Plant Biology Department of the Carnegie Institution for Science.
The Chinese tallow tree, or Triadica sebifera, has two origins in the US. The first of its kind were introduced from China to Georgia and South Carolina through Benjamin Franklin in the late 17th to early 18th centuries, while a second group was brought over by federal biologists in the early 19th century from eastern China. Since then, these trees have spread across the US as an invasive species.
While the tree may seem average most of the year, its beauty is brought out during the autumn when its heart-shaped leaves transform into shades of yellows, oranges, purples, and reds This tree also has many applications and qualities that beg further research.
Most of the potential applications of the Chinese tallow tree come from its seeds. The seeds have two parts that can be used: the outer, waxy layer called a tallow, and the inner kernel. The seeds are used as purgatives as well as to heal wounds in Chinese medication, which are uses that arise from the saponin in the seeds. Saponins are lipids decorated with sugars that can dissolve in both oil and water (like soap) and can be both toxic and antimicrobial.
They may also increase the ability of our immune systems to kill cancerous cells. The seed’s tallow can be melted and the wax used for making soap and candles. Perhaps the most exciting application is related to how the seeds are made up of 45% – 60% stillingia oil—the chief components of which are unsaturated oleic, linoleic, and linolenic acids. This oil can be processed into biofuels and used as an alternative fuel source.
The Chinese tallow tree has spread across the world, resulting in some differences between the invasive and native populations. One region the tree has populated is the southeastern US. Due to the lack of their native insect pest in the US, the trees have lost their chemical defense system and devote more of their resources to growth rather than defense. As a result, US trees grow about 30% faster than their Chinese kin.
However, the trees in the US out-compete the native trees even when grown in China, despite the US group’s lack of chemical defense against the pest and subsequent damage, raising some interesting questions about what makes a species competitive and adaptive.
We all prefer some kind of balance in our lives. Nature, too, tends towards balance: organisms need to both grow as well as defend themselves. However, the fact that the defenseless US Chinese tallow trees out-competed the “more balanced” Chinese populations undermines this concept. Most species don’t put all of their energy to growth or defense, and generally have a balance between the two.
Understanding why this norm is contradicted by the Chinese tallow tree in the US will help establish how specific invasive populations of species come to be. And maybe understanding the role of balance in nature might even bring out new ways we ought to balance our own lives in the modern world, where we are rushed to excel at so many different facets of life simultaneously.
Ankush Bharadwaj is a 2018 summer intern at the Rhee Lab in the Plant Biology Department of the Carnegie Institution for Science. He is currently an undergraduate student majoring in Microbiology, Immunology, and Molecular Genetics at the University of California, Los Angeles. His hobbies include being outdoors, where he usually spends his time kayaking, hiking, or simply skateboarding around.