By Teague Dilgen
The meticulously curated grounds at Rockefeller’s sixteen acre oasis host a wide variety of flora. As listed on the university’s tree map, the campus boasts a whopping forty-seven species of trees. Upon taking a role as a research assistant at Rockefeller, I was astounded to see such a verdant island in the middle of our concrete sea. Being an avid botany enthusiast and the child of an NYC Park Ranger, naturally, I spent my first week touring the grounds with the university’s tree map in hand to familiarize myself with some of the species with which I was less acquainted. In the recent years of my time as a plant-nerd in NYC, it has been a challenge to find spaces and time within which to observe such a dense diversity of flora as that hosted by Rockefeller. While I am fortunate enough to frequent our botanical gardens and vast parks on the occasional weekend and holiday, I find it most convenient to be surrounded by a Zen Garden at the workplace. During my inspections of the campus gardens, I noticed some of the more common street trees I had seen growing up in NYC: the London plane tree, the much contested Callery pear, and the honey locust.
It was particularly delightful to see so many types of dogwoods and crabapples but, above all, I was thrilled to see the Ginkgo biloba right outside of the Rockefeller Research Building. The Ginkgo may be familiar to some for its extract, often marketed as a treatment for blood disorders and memory issues1. In addition, it’s used as a symbol in many Asian countries. For example, the Ginkgo leaf can be found as the Symbol of the Tokyo Metropolis. While these virtues alone are enough to arouse my fondness for the Ginkgo, I’ve recently developed a deeper appreciation for this species due to its status as an evolutionary unicorn.
Roughly 300 million years ago during the Mesozoic era, the seed-bearing Ginkgoaceae family gave rise to an estimated sixteen genera2. These genera were spread over the entirety of the world. The genus which contains the Ginkgo biloba we know and love today is believed to have evolved sometime around 170 million years ago. Most interestingly, it has remained largely unchanged since then. By around 2.5 million years ago in the middle of the Pleistocene epoch, cycles of extreme glaciation and deglaciation forced all Ginkgos to the brink of extinction2. Only a few populations remained of a single species within the genus of Ginkgo. Impressively, the species is also the only remaining genus in the Ginkgoaceae family, the only family in its Ginkgoales order, and the only order in its Ginkgoopsida class. To put the Ginkgo’s uniqueness into perspective, it may be helpful to think about another division of spermatophytes, the clade to which contains almost all seed producing plants. Conifers, or pinophyta, are one such example. Pinophyta contains six living families and an estimated 630 living species, whereas Ginkgophyta contains only one living family and one living species3. This stark contrast between just these two clades of living, seed-bearing plants is staggering and further emphasizes the remarkable individuality of the Ginkgo.
Like many Ginkgo fanatics I’ve encountered over the years, I was brought up on a highly romanticized story which told of Buddhist or Taoist monks who saved the Ginkgo from near extinction. It is said that the monks recognized the tree for its distinctiveness and bold yellow leaves and thus safeguarded the species at their monasteries for millennia. While it is true that there are great populations of Ginkgo surrounding human settlements in China (which is likely the basis for this tale), it has been well agreed upon since the 1920s by geneticists, botanists, and anthropologists alike that this story is false, as evidenced by the presence of native populations of the trees outside of monasteries4. Anthropologists suggest that these older monastic trees (some between 1000-3500 years in age) are found near settlements because of their ability to produce their famous butyric acid-filled fruit5. Despite their smell–that reminds many of the scent of vomit–and the presence of a compound like urushiol, responsible for poison ivy rash, and other toxins, ginkgo nuts are quite a delicacy when prepared properly6.
While it is unknown how many singular Ginkgo trees existed prior to their adoption as an ornamental and fruiting tree, it may be said with great confidence that the Ginkgo’s population has greatly increased because of their association with humans. It is my opinion that the monk fable does not stretch the truth too far and, in many ways, humans have saved the Ginkgo. It has transitioned from a species found only in remote mountain ranges of China to one of the most well-known trees in the world. The success of the revitalization of the Ginkgo can be seen wherever you look. One estimate predicts there are tens of millions of Ginkgos on the continent of Asia alone. This is also exemplified right here at home in NYC. As of 2018, the five boroughs housed an estimated 60,000 Ginkgos, and that number is only growing5. Whether through glaciation or habitat destruction, Ginkgo could have easily “gone the way of the dodo,” but thanks to safeguarding by human societies, it is thriving around the globe.
Despite the rejuvenation of this “living fossil,” the Ginkgo has been designated as endangered on the International Union for Conservation of Nature (IUCN) Red List since 1998, an appointment which likely needs updating7. The IUCN Red List (which tracks global biodiversity and designates different species on a scale depending on their proximity to extinction) recognizes 44,000 species at risk of extinction. As this figure grows yearly, it may be helpful for us to use the story of the Ginkgo as a framework upon which to build our future. With this model in mind, we may be able to maintain what is left of our biodiversity by nurturing threatened species. But this is not enough. To quote a 2019 article from Peter Crane who inspired this piece through his book Ginkgo: The tree that time forgot, “Ginkgo reminds us that conservation through cultivation is an important means of protecting threatened plants… [but] must not cause us to forget the conservation of natural habitats.”5 While legislation must be put into place to hold corporations accountable for the terror they inflict upon the natural world, there is still much that individuals may do to help. To discover ways in which you can help right here in our city, check out the New York Restoration Project at www.nyrp.org and the City Parks Foundation at https://cityparksfoundation.org/volunteer-its-my-park.
