Dear Reader,
Today I want to talk about a rare and interesting sight: the Double Tree of Casorzo. Before anyone asks, no I am not referring to a DoubleTree hotel in Casorzo. Between Casorzo and Grana in Piemonte, a region in northwest Italy, there is a cherry tree growing healthily on top of a mulberry tree with branches spreading over 5 meters long. This tree, or should I say, these trees, are known as the Double Tree of Casorzo (Bialbero de Casorzo in Italian) or the Grana Double Tree.
Image © Alfio Cioffi
As you may already know, it is not common by any means to see a tree on top of another tree, but somehow, someway, this cherry tree managed to find its home on top of this mulberry tree. It is unclear how exactly this double tree grew to be, but one popular theory is that a bird dropped off a cherry tree seed on top of the mulberry tree. The cherry tree seed then spread its roots down through the hollow trunk of the mulberry tree and found a connection to the soil where it can absorb nutrients. The relationship between the two trees does not appear to be parasitic or harmful to one another. It is fascinating to see that the mulberry and cherry trees are able to share water, sunlight, soil nutrients, and most importantly space without outcompeting one another and growing just fine.
Plants growing non-parasitically on top of other plants are not uncommon and are known as epiphytes. Common examples of epiphytes include some species of ferns, orchids, and bromeliads, which can attach themselves to trees or other plants and absorb some nutrients from rain and air along with any other nearby debris or soil they can access; all while not harming its host. What makes the Double Tree of Casorzo unique is that most epiphytes either are small in size or have a short lifespan due to lack of space and humus. However, as you can see in the photo within this article, this cherry tree is quite tall and healthy!
I talked to ISA Certified Arborist Andy Bartram (Crew Production Manager, Russell Tree Experts) about these trees to get his thoughts and opinions. Without seeing the tree in person, he believes the bird seed theory is plausible and he’s interested to know what the cherry tree’s root system looks like. As mentioned earlier, the cherry tree’s roots could be spreading down through the hollow trunk of the mulberry tree to get its nutrients, but there is also a chance that some grafting between the cherry tree and the mulberry tree’s root system could be occurring. The cherry tree could also be receiving nutrients from any available rain and mulberry leaves. I asked Andy about the tree’s health and longevity. In terms of treatment, if the trees have been growing healthily without any human interference, then they should be left untouched. If needed, watering during dry periods or seasonal fertilization could also aid in their health and growth. On a final note, Andy was curious about the structural rigidity of the Double Tree of Casorzo. With the cherry tree’s root system being higher off the ground (or potentially grafted to the mulberry tree), it may pose a hazard during windy days for visitor safety. If so, the fence surrounding the trees is definitely necessary and may even need to be extended as the trees continue to grow.
So if you ever take a trip to Piemonte, Italy, visit this tree and feel free to share any photos or videos you take! This Double Tree of Casorzo is definitely something you do not see every day!
Enrique Arayata I Media Production Coordinator, Russell Tree Experts
Enrique is a fourth year student at The Ohio State University majoring in moving image production with a double minor in photography and film studies. In his free time, he enjoys running, spending time with his girlfriend and family, photography, and creating YouTube videos.