I’VE BEEN READING a historical biography lately, the subject of which is not a person, but a tree, a species with a life story spanning nearly 250 million years and much of the globe. The main character is the venerable and distinctive ginkgo.
The book from Yale University Press is called “Ginkgo: The Tree That Time Forgot,” and its author—the tree’s biographer, really—is Peter Crane, former director of the Royal Botanic Gardens, Kew, and current dean and professor in the School of Forestry and Environmental Studies at Yale.
He joined me on my public-radio show and podcast to talk about Ginkgo biloba—about why it is “the platypus of the plant world,” how a love poem by Goethe helped popularize the tree, and how there are now more than 200 cultivars with diverse habits, leaf shapes and even leaf color, all stemming from that one remaining ancient species.
Read along as you listen to the Dec. 14, 2015 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
my ginkgo q&a with peter crane
Q. The book, which reads like a biography and history combined, begins with the first ginkgo that made its mark on you, one that stood near your home on the Kew grounds when you were there.
A. This is one of the oldest ginkgos in Europe, certainly one of the oldest ginkgos in England. It dates from the early 1760s. That makes it 250-plus years old. It’s one of the great, legendary trees of Kew.
It’s what we used to call one of the Old Lions—one of original trees that dated from the formation of the Royal Botanic Gardens, Kew, by Princess Augusta in the late 1750s. It was probably obtained from a nurseryman working in East London at the time. Somehow, he was getting plants from the East, probably from China or possibly Japan.
There are a number of trees of the Kew site, of which the ginkgo is one, that came from those early introductions. It’s a magnificent old tree, and one of our most precious trees on the Kew grounds. It was one that we always worried about when there was a big storm or something.
Q. It was astonishing to me that this tree was not only known to you, when you were director there, but it’s a tree that the first director of Kew, William Jackson Hooker, who was there in the 1840s, knew as well.
A. Absolutely. He would have known that tree—all the directors over the years would have. They come and go, and I’m one of the ones that has come and gone. It would have been planted a good 70 or 80 years before Hooker was even appointed—it was planted when it was a royal estate.
Q. Many other esteemed botanists and tree experts and plant explorers have had a ginkgo chapter in their careers, and the book is filled with wonderful tales of them. The supporting cast around this great tree includes men’s names I know not because I knew their individual stories, but that I recognized because they became the specific epithets, or species names, of certain plants I know. Names like Kaempfer, or Siebold, or Thunberg—they were brought to life for me in the story of this ginkgo. [For example, the Japanese larch is Larix kaempferi; the Japanese barberry Berberis thunbergii; the popular sedum, Sedum sieboldii.]
A. Those three in particular were three fascinating characters in the history of plant exploration more broadly, not just in the history of the ginkgo. All three of them were physician-botanists to the Dutch East India Company, based in southern Japan, in Nagasaki harbor, on a small island called Deshima. [Above, the island in a 1669 engraving.]
For several hundred years this location was the only contact that Japan had with the West. These three botanists—Kaempfer, who was there in the 1690s, and Thunberg, who I think was there in the 1790s, and then Siebold, who was there in the 1820s, were kind of close observers of Japanese life as a whole, but close observers of Japanese plant life.
It was Kaempfer who first noticed and described ginkgo, as he transliterated it from the Japanese. But Thunberg saw it, and then Siebold did a magnificent illustration of it when he returned home from Japan, in his “Flora Japonica,” published in the 1820s [below].
Q. The tree is a botanical oddity in many ways—a bit of the “platypus of the plant world,” as you write in the book.
A. Rather like the platypus, the oddity comes in its reproductive system. The platypus is a mammal, but curiously is not giving birth to live young, but is laying eggs. That’s a bit strange for a mammal. What that is, is a holdover from the reptilian ancestors of mammals.
Ginkgo has a kind of similar story. During its reproductive process, the last little phase of it that there are swimming sperm cells produced by the pollen grains. Swimming sperm cells is not something you would see in a normal tree. This is something you would see in a moss, or in a fern. So in a way, just like the platypus, it’s a holdover of an ancestral feature that hasn’t quite changed yet.
When that was discovered—by a Japanese scientist in the last few years of the 19th century—it was an astonishing discovery, because no one really expected it. It contributes to why botanists in particular are interested in this strange, peculiar, isolated tree that’s so different from all the other trees we have.
Q. So that’s one way it’s different. There is a passage in the book that says: “It’s the only member in its genus; the only genus in its family; the only family in its order, which is the only order in its subclass.” It’s a loner. [Laughter.]
A. It’s totally a loner. I always say there are five different groups of seed plants, and one of those groups is ginkgo. [Laughter.] In some of those other groups, among the flowering plants, there are 350,000 species, contrasted to ginkgo, where there is just one species.
Q. So in five groups of seed plants, it’s one of the groups all unto itself.
A. There would only be four if we’d lost ginkgo.
Q. You were speaking a bit about its reproductive habits, and there are separate male and female trees, yes?
A. There are, which is not so unusual. Yew trees also have male and female. But it really kind of matters in the case of ginkgo. I was just looking at some ginkgos this past weekend. The leaves are mostly off the trees now, so you can see the fruits—or the seeds, which is what they are in correct botanical parlance—and some of these trees produce vast quantities of seeds, just on the female of course.
And then the seeds drop, and then the seeds smell.
Q. They do. [Laughter.]
A. They have a terrible, putrid odor that they produce, particularly at this time of year as they hit the ground and start to rot. Probably that smell is something to do with the way those seeds are dispersed, or were dispersed in the past. But it’s not the kind of tree you’d like to have growing outside your front door. [Laughter.]
Q. Not a female.
A. Not a female.
Q. Where do we think it began 250 million years ago on the earth?
A. We don’t really know where it began. But what we do know from the fossil record—because the leaves are so distinctive, it’s easy to spot in the fossil record—is that we have it both in the Southern Hemisphere and the Northern Hemisphere, and on all of the continents.
You see it in South America, in Australia, in Antarctica, in India—but you also see it in East Asia, Europe, North America. This was a widespread plant. Between about 200 and 100 million years ago, we know there were multiple types of ginkgo, all with basically the same kind of leaf but some subtle differences, and also subtle differences in the seeds and the way the seeds were borne.
So we know there were different species of ginkgo on the planet, but today we just have the one.
Q. I loved the fossil images in the book, impressions left behind by leaves—and you included examples from Afghanistan, Scotland, North Dakota! Have you gone around the world and visited living trees? Do you go on ginkgo adventures? [Laughter.]
A. I have done some looking at living trees and at fossils. Usually when I see the fossils I’m collecting more broadly than just ginkgos. But I have collected ginkgo in North Dakota, in northern England, in Mongolia—I’ve seen it in a bunch of different places. This was a widespread plant, which is all the more paradoxical in that today we just have this one living species left.
Q. In one timeline diagram I saw on the origin of plants it’s older than conifers but younger than cycads, I believe.
A. Yes, it goes back to about 250 million years, which makes it older than most of the trees we’re familiar with—the flowering-plant trees. It’s a little younger perhaps than the conifer lineage, but older than most of the conifer genera that we know. And around the same age as the cycads, but significantly older than most of the forest trees that we’re familiar with.
Q. I remember many years ago interviewing a botanist at the New York Botanical Garden, the cycad expert Dennis Stevenson, and he pointed and said: “They have motile male gametes.” So what you were talking about before: the swimming sperm of these ancient plants.
A. Exactly. When this was first discovered, it was in ginkgo, by a man called Sakugoro Hirase working at the University of Tokyo in about 1898. Remarkably in the same year another Japanese botanist also working in Tokyo discovered the same phenomenon in cycads. They’re the only two groups that it occurs in; you don’t see it in conifers, or any normal flowering-plant tree. So they’re the same in holding over this primitive, water-reliant mode of reproduction.
Q. It was a watery world, yes?
A. [Laughter.] Yes, indeed.
Q. Another oddity you cite: You say in the book that the ginkgo has, “the most synchronized leaf drop of any tree I know.”
A. It’s lovely, and again at this time of year, in the fall, this is the time when they’re dropping their leaves. It’s not always true but it often is that a large portion of the leaves—which are brimstone yellow in the autumn sunlight—a huge proportion of those leaves come down on one night.
I was back in Chicago recently, and we had a big snowstorm. Then after the storm, it settled and the next night many of the ginkgo—that was their night. You had this wonderful white snow and then this beautiful carpet of yellow leaves under every ginkgo tree. It was stunning. At this time of year those leaves are magnificent, and when they all come down at once, you have this incredible carpet of yellow. [Above, ginkgo in Ueno Park, Japan.]
Q. Mankind has been cultivating the ginkgo for about 1,000 years. It has many places in our human cultures–including some pretty obscure ones that you wrote about, like the way sumo wrestler’s ponytail?
A. This little fan-shaped leaf has been taken up in all kinds of ways, particularly in Japanese culture, but also in Korean and Chinese cultures. The shapes of things that are fan-shaped are often referred back to the ginkgo. I love that one of the old common names for ginkgo in the Chinese literature is duck’s foot—and that again refers to the kind of webbed shape of the leaf, like the webbed foot of the duck. This idea of the ginkgo leaf shape has found its way into many cultures, particularly in the East.
Q. The Arts and Crafts movement, too, yes?
A. Absolutely. You see it decorated on the side of houses, on vases, on prints. It’s such a beautiful and common motif. I think it gained quite a bit of impetus from Goethe’s engagement with the tree, too, which is an interesting story in itself.
Q. Tell me a little bit about that.
A. Goethe quite early—around about 1815—wrote a very famous poem called “Ginkgo biloba.” He wrote this poem to a young lady he was very fond of, and he pasted onto the bottom of his letter two dried ginkgo leaves. He asks in the poem, is this one leaf divided in two or two leaves joined together as one? It’s a very famous poem in Germany, and I think part of the interest particularly in Europe and particularly in the German-speaking world, flows not only from the botanical interest and the beauty of its leaves, but also its association with Goethe.
Q. As you note in the book, ginkgo is “a plant of parks, gardens or city streets…all human-created habitats.” But even though this was this relatively small gene pool left to draw upon, we’ve managed to come up with more than 200 cultivars today. Are there really that many?
What’s the generic ginkgo like, versus these cultivars? If I’m going to make room for a tree, let’s talk about the different ones as plants for the landscape.
A. There are various things that you can focus on when you are thinking about a ginkgo cultivar. One is the overall shape of the tree: What do want the shape to be like?
There are tall, thin ones that are kind of appropriate for narrow spaces. One of these that is often planted in cities is called ‘Princeton Sentry.’ But there are others that are kind of short and more shrubby, and others that are more spreading. There are a range of different habit types to suit different situations, and then there are also different leaf types.
There are variegated ginkgos, and cutleaf ginkgos—like you might have a cutleaf oak. There are ginkgos where the leaf is not properly unrolled, and they look like little trumpets. There is also some variation not only in the habit, but also in the leaf form. These are all basically vegetatively reproduced selections from mutations that have been picked up in seedlings.
Across the street from my office there us a female tree, and there are lots of little ginkgo seedlings coming up beneath the tree. A certain proportion of them have slightly different leaves, so the way these varieties have been propagated and brought into the trade is by selecting those mutants.
Q. How big can a ginkgo get? How big are some of the old-timers? [Above, a tree at Tokyo’s oldest temple, Senso-Ji.]
A. When you see these big trees in Japan, they can be very large indeed, well over 100 feet tall, and even much bigger than that, and big, spreading trees. They can reach an enormous size.
We think that they are quite long-lived also. They can become an absolutely massive tree. Even ones that are planted here in gardens can become, in the right situation, a pretty good-sized tree. They’re not a slow-growing tree, or an especially fast-growing tree—they’re kind of middle-of-the-road, but they put on a lot of growth and over time can become quite sizeable.
You often see both in Japan and also in New York that they sometimes need a lot of pruning and even pollarding to keep them under control. Which is why in the streets they prefer something like these tall, thin ones that don’t spread too much.
Q. Like the ‘Princeton Sentry’ you mentioned. As a street tree those are more desirable.
A. Particularly if you’ve not got a lot of space for it to expand. In Japan you often see them pollarded really severely—cut right back. It’s an incredibly resilient tree and will produce new growth each year, which will need cutting back.
Q. I wanted to hear more about what you describe in the book as the trees, as they age, having almost stalactite-like growth. I have never seen a very old one such as you have been privileged to. What is that?
A. As far as we know, these are pretty much like normal branches, but instead of growing upwards they grow downwards. When they hit the ground they send up sucker shoots. In a way you can think of it as a form of vegetative reproduction. It’s a way that new suckers are propagated.
You don’t tend to see it very much in North American trees—I have seen it occasionally in North American trees, but it tends to be a phenomenon of much older trees. I don’t see it, for example, on that Kew tree, which is 250 years old, but you see its greatest expression in some of these big old trees in Japan and China. And there, the development of these stalactite-like down growths is really a pretty striking feature of the tree.
Q. Is ginkgo just a tree of the temperate zone?
A. I think it’s very much a tree of the temperate zone. At least the ginkgo that survives today needs a kind of cold winter, but it also need a warm summer to grow really well. It’s perfectly adapted to the middle of the U.S. It starts to not feel cold enough for it, I think, in central and southern Florida.
And even looking at the difference between, say, Houston and Dallas—and how cold the winters are normally there. Ginkgo struggles a bit in Houston, but does better in Dallas. Obviously it depends on exactly where the tree is growing, but in general, you need a kind of nice, cold, good hard winter.
It finds Chicago just fine, for example. Of course even ginkgo has its limits, and while it will grow in Toronto, there are limits to how far north in Canada it will grow. It needs a good growing season to put on a good amount of growth, and it needs water, too, of course.
enter to win the book
I’LL BUY A COPY of “Ginkgo: The Tree That Time Forgot,” for a lucky reader. All you have to do to enter is answer this question in the comments box below, all the way at the very bottom of the page:
Is there a ginkgo in your garden, or are ginkgos a feature of your town’s main streets, perhaps? What surprised you about the ginkgo after reading or listening to this interview?
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looking for unusual ginkgos?
PLANTSMAN TONY AVENT of Plant Delights Nursery doesn’t sell ginkgos, but he introduced me last year to the Nichols brothers, Matt and Tim, who offer male plants of more than 50 ginkgo cultivars from their North Carolina nursery and by mail. (Their other obsession: Japanese maples, a plantmania they inherited from their father.) If you want to see how ginkgo obsession looks, browse their collection of cultivars, including variegated-leaved ones (above).
prefer the podcast version of the show?
MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the Dec. 14, 2015 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(Photos from “Ginkgo: The Tree That Time Forgot” Facebook page; fossil of G. cordilobata from Naturhistoriska riksmuseet; Deshima island engraving from Wikimedia; Goethe poem image from Wikipedia; Siebold plate from “Flora Japonica” from The Ginkgo Pages. Variegated leaf silhouette from Mr. Ginkgo online catalog. Disclosure: Purchases from Amazon affiliate links yield a commission.)