Sometimes we have plants growing in our garden collections that aren't quite who we thought they were. Usually when we receive a new accession into the living collections, we have information of what the name of the plant is, where it came from (nursery or collection site in nature) and if it is a seed, cutting or plant. Fortunately, 99.9% of the time, the listed name is correct. Unfortunately this 0.1% can create a plant "identity crisis" for us!
Recently this occurred for a tree growing in the Boettcher Memorial Tropical Conservatory. It had been labeled as Garcinia mangostana (mangosteen, a tropical fruiting tree) and in the 8 years that I walked past the tree, mapped it, photographed it in flower and wondered if it would ever fruit, I took it for granted that it was, in fact, Garcinia mangostana. A researcher from Kew Gardens in England contacted me to learn more about the G. mangostana and how it was doing in our conservatory. I proclaimed that it was healthy, about 20 feet tall and had flowered but never fruited. The researcher's excitement at this communication made me wonder what was so special about this plant which I then Googled, took one look at the pictures of the flowers and said "Oh no!" You see, the images were of medium-sized pale pink flowers and our plant's flowers are extremely white and miniscule in size.
So this is when the fun really begins to find the true identity of an unknown plant. I looked up all the inf0rmation I could find about the accession, including the nursery we originally received the plant from. I checked out their online catalog to see which plants they carry that could match our unknown plant. I also e-mailed that nursery and attached a digital image of our tree in flower to see if I could get any further information. But I didn't hear back from them.
During this time I continued to communicate with the researcher, sharing information about the leaf size and shape, bark coloration and any other details I could discern from our currently non-blooming plant. I sent additional images as well. I also took a leaf and stem sample to see if there was any latex in the plant, and if so, what color it was. (It was white.) While waiting for information from her and the herbarium at Kew, I continued to research this plant too.
My first searches in the Helen Fowler Library yielded no help as I didn't know where this tree might be native to. I was limited to titles like Tropical Trees, Tropical Ornamentals and Identification of tropical woody plants in the absence of flowers and fruits. All of these references might have been handy, just not for this particular mystery plant.
Part of the mystery was also verifying that this plant was even still in the same genus or family as the original identity suggested. To do this, I skimmed through Flowering Plants of the World by V.H. Heywood to see what other possible families it might belong to including the Clusiaceae family that was its original identity. My list included about 10 families, including Clusiaceae, that have opposite leaves, latex, lack stipules on the leaves and include woody plants.
As a starting point to my research, I decided to look at what plants in Clusiaceae, starting with the genus Garcinia, are in other botanic gardens since chances were good that this was not the most uncommon plant in the world, just rather uncommon in Denver.
A Web search of a collections sharing site yielded four species in cultivation. Garcinia acuminata, G. brasiliensis and G. tinctoria at The New York Botanical Garden and G. spicata at the Royal Botanic Gardens Edinburgh. Edinburgh also yielded a long list of herbarium specimens from tropical Asia. I decided to start my search with G. spicata, just by chance, and the first image that I saw that was not of a fruit, was an amazing match to our unknown plant. The challenge though was that the Web page I was directed to was in Chinese and I never have quite trusted the Google translate tool to be 100% correct, so I was left questioning if the image was really for the species I had queried.
So where to from here??? My next search was to determine where this species was native to in hopes of finding a key to help me verify a match. For this search I went to a couple of handy online databases that we commonly use to track plant names in our local database, GRIN Taxonomy and Tropicos. Through these sites I learned that the species is native to Sri Lanka and India, so it was back to the library for me.
My initial search in the electronic card catalog taught me that Sri Lanka was once known as Ceylon and from this information I found A Handbook to the Flora of Ceylon and in it a description of G. spicata. From the image you might notice that there are almost handlike structures that are the stamens (the male part). The description from the flora of this structure was the key to this identification,
"Stamens combined into 5 erect, spathulate bundles of 8-10 each."
Ding, ding, ding, we have a winner! Armed with this information, I contacted Fairchild Tropical Botanic Garden with a description of our plant and an image of the flower. The curator of tropical fruit, Richard Campbell, confirmed that yes, it was indeed a match to their G. spicata plants. Mystery solved. To follow up on this new information, the proper name was recorded in our database for this plant and a new label will be ordered for it this spring.
And now I can continue on to find the next mystery plant's true identity.