Could it be so happy because it offers hope for cancer treatments? The Xi Shu (translated as "Happy Tree"), Camptotheca acuminata, is native to warm, humid stream banks south of the Yangtse River in China and Tibet. Though it is not a new introduction to the Western Hemisphere, it is apparently not often grown outside of China. It is rare enough, in fact, that our Dave's Garden Plant Files had no record of it!
(Editor's Note: This article was originally published on November 5, 2007. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
Some plants that I desperately seek come to my garden only after considerable effort, or sometimes not at all. The "Blue Shrimp Plant" (Cerinthe major) has been on my "wish list" for several years, but it still eludes me. No one locally that I know is growing it (which is usually a good indication that it probably won't grow in my climate, but that won't stop me from trying!). I've not yet been able to work out a plant swap nor accrued the cash and the gumption together at the same time to order a Cerinthe major from a nursery. Perhaps I like the idea of my garden being not quite complete, and I enjoy the promise of knowing there are new plants I must grow before I give up gardening and lay down my hoe?
On the other hand, some fascinating plants show up as a pleasant surprise without much work on my part. That was the case with my acquisition of a healthy six-foot sapling of Camptotheca acuminata -- called Xi Shu ("Happy Tree") in China where it is a native plant. My coworkers were recently clearing out the plant nursery at the Jacksonville (Florida) Zoo and Gardens where I work part-time in the Horticulture Department. Space was needed for daily tractor-trailer truckload deliveries of hundreds of potted plants for our new garden. Several C. acuminata trees had been languishing in the nursery for a year or more without ever finding an appropriate spot in the zoo gardens. These young trees were offered up as freebies to the zoo staff along with some other unique plants to make room in the nursery for the new arrivals.
I didn't precisely know what I was getting when I hauled home one of the orphaned trees, but it was something new to add to my "one-of-everything subtropical cottage garden." I rarely pass up the opportunity for a plant that I don't already have. The tree came only with its botanical identification and some Internet information that it is known as the "Happy Tree" or "Tree of Joy" in China. It is used as a street tree in some cities in China and has also been used effectively in Chinese medicine for many centuries.
When I want to find information about a plant, my first resource is the Dave's Garden (DG) Plant Files. I rely upon the Plant Files to provide data for the optimum growing conditions for plants. Our Plant Files seem now to be the "standard of the industry" for plant information. I know that my local Agricultural Extension Office personnel look up plants on Dave's Garden, as do other horticultural professionals and gardeners I've met and with whom I have discussed the Plant Files. I especially gain insight from the comments in the Plant Files that other DG subscribers have shared by reporting their personal experiences with growing a particular species or cultivar.
I was astonished when I could find no information in the Plant Files when searching the botanical name of Camptotheca acuminata or the common name of "Happy Tree."
Only once before have I come upon a plant that didn't have a page in the Plant Files. Upon buying my current property about six years ago, I was thrilled to find an unusual single-leaved fern-like plant spreading a few yards from the base of an oak tree. My investigation and research revealed that I had a well established stand of a native plant, Southern Grapefern, Botrychium biternatum (neither rare nor endangered in Florida, but infrequently seen). It was amazing that the delicate Grapefern had somehow survived the decades of mowing to which the previous owners of the property must have subjected it. I was a neophyte on Dave's Garden at that time. I wasn't sure why I couldn't find any information on B. biternatum on DG. As it turns out, no one had yet input any data or photos for the plant. I, therefore, got to do the honors of recording the information for this diminutive forest beauty. The experience of creating the Plant Files page for the Southern Grapefern was probably not as exciting as the "Eureka!" moment a botanist might feel upon discovering a plant previously unknown to anyone, but plugging in the photos and information for B. biternatum did instill in me some semblance of a sense of discovery. Dave's Garden truly is "For Gardeners, By Gardeners," as the website motto states. We all get to play our part in building a unique database of botanical and horticultural statistics as well as relaying our down-home, practical, common sense methods and wisdom gained by experience that have worked for us in cultivating our personal gardens.
In the case of the "Happy Tree," there was not even an entry for the Camptotheca genus in the DG Plant Files. That part of the data input had to be done by the friendly administrative folks that maintain the site. Once the page for the Camptotheca genus was available, it was up to me to find out as much as I could about the plant and then input the correct information. I could proceed with some confidence because, fortunately, there are those amongst us (myself included) that are nitpickers about the Plant Files. If incorrect information is provided in the details on a page, the mistakes can be reported and corrected by clicking on the "Report Errors" button at the top of each page.
My research for Camptotheca acuminata turned up some intriguing factoids:
The plant grows quickly to about 75 feet high and can make a canopy about 40 feet wide! Fortunately, it can be pruned back without damage. It is a deciduous tree in the Tupelo family (Nyssaceae). Its branches are reported to grow only near the top of the tree. From my own observations of my C. acuminata, its reddish-green leaves seem to resemble those of an avocado tree (Persea americana), but with heavier, pleated veining.
The genus name, "Camptotheca," may be translated from the Greek as "curved sheath." It probably refers to the small, banana-like pods emanating from a central point to form a round cluster that is the fruit of Camptotheca acuminata.
Parts of the "Happy Tree" have been used from times of antiquity to the present day in traditional Chinese medicine to provide treatments for ailments as diverse as psoriasis, liver and stomach ailments, and common colds. It is also used to treat leukemia. This latter use led to scientific study to determine if there actually was an anti-cancer compound in C. acuminata. The cancer-fighting properties were first verified in 1958 by Dr. Monroe E. Wall of the USDA and Jonathon Hartwell of the National Cancer Institute in the United States.
The active ingredient in the plant was found to be Camptothecin (a pentacyclic quinoline alkaloid). The stem bark, root bark, and seeds can yield trace amounts of Camptothecin, but the highest concentrations may be in the tender young leaves. Camptothecin and its analog compounds can inhibit the nuclear DNA topoisomerase I enzyme and has the effect of interrupting the replication and transcription of cancer cells.
Camptothecin is not water-soluble and can be highly toxic, making it difficult to administer as a medicine.
After decades of extensive trials, several relatively safe and effective water-soluble semi-synthetic analogs of Camptothecin have been developed. These include the brand names Camptosar by Pharmacia, Hycamtin by GlaxoSmithKline, and CPT11 by Aventis. Worldwide sales of these drugs have collectively reached about $1 billion annually. The raw material for these drugs is still only available from the C. acuminata trees.
The harvesting of C. acuminata for the pharmaceutical industry has decimated the population of the endemic trees in China. The tree may now be considered as "Endangered" by the government of China and export is severely restricted. It is estimated that less than 4,000 of the trees remain in the wild in China.
In June 2000, an abstract discussing efforts to grow C. acuminata in Louisiana as a silviculture crop to supply raw materials to the pharmaceutical industry was presented at the U.S. Forest Product Society's 54th Annual Meeting. It is not known if the plan to commercially cultivate C. acuminata was implemented.
One source stated that all the C. acuminata trees in the United States came from the seed of two trees imported by the USDA in the 1900's (making my tree an "heirloom!")
Despite all my online research, however, I couldn't find any explanation as to why the C. acuminata had been given the common name of "Happy Tree" in China. There was neither a myth nor fable I could locate to explain the tree's connection with happiness. Since we are an international community on DG, I decided to contact a subscriber in China to see if there was any folklore associated with the C. acuminata that would explain why it is the "Happy Tree." The response I got from Jianhua in Shangshui, Henan, China, was poetic:
"The tree is tall (20 -- 30 meters) and straight upwards, which looks like a handsome man. And the leaves, light green and bright, a huge canopy on top of the tree. Once you see the tree, you cannot help being happy. That might be why it is called Xi (happy) Shu (tree). The above is a summary of a Chinese online blog. In my opinion, the tree is so called for another reason. In the 1770s, Chinese herbalists found its medicinal functions -- to treat cancers, the excitement you can imagine. They think surely the tree can bring people happiness, and thus they name the tree as 'happy tree'. As a matter of fact, till then people had regarded the trees as just trees: they cut them down as burning wood or make into paper. Many people even did not know the name of the tree. And there was not a formal name for it. The only recorded name about the tree in an ancient plant book was in Mr. Wu's 'Zhi Wu Ming Shi Tu Kao' (Studies of Plant Names with Illustrations). It is called 'Han Lian' - Han means dry, and lian means lotus, if explained in English, it is a plant which grows on land and has lotus-like seedpods."
Regardless of the etymology of its common name, having spent so much time becoming familiar with the history, growing conditions, and contemporary uses of Camptotheca acuminata, I cannot now look upon it without a smile and a warm and fuzzy feeling, such as I might experience with any close personal friend. So, it is certainly, for me, my Happy Tree!
I would be very interested in knowing if anyone else is growing C. acuminata. Your comments and questions are welcome. Please post a note below.
About Jeremy Wayne Lucas
Jeremy (JaxFlaGardener) is a frequent contributor to the Florida Forum and other forums on Dave's Garden. In an ideal world, he would spend nearly every waking moment gardening, oil painting, and writing. Lacking such a Utopia, he currently works part-time in the Horticulture Department at the Jacksonville (Florida) Zoo and Gardens. His own half-acre garden is a hodgepodge of just about everything that will grow in Zone 8b/9a, with a homemade greenhouse for his orchids. He is a Master Gardener who esteems digging in the dirt more than book learning, but greatly enjoys research about plants and botanical nomenclature. He is pictured here with one of his large paintings, "The Healer's Leaves," based on a wonderful photo by DGer GardenWife of Ricinus communis (Castor Oil Plant) used by permission.