WHEN YOU’RE TALKING plants and not people, how do you figure out who lives where? You can’t send census takers door to door to get a head count, but doing so is a critical step in devising conservation strategies in a changing world, among other key goals. A New York Botanical Garden botanist is coordinating such an effort.

Dr. Robert Naczi is the Arthur J. Cronquist Curator of North American Botany at the New York Botanical Garden, where the classic reference to the plants of all or part of 22 U.S. states and five Canadian provinces is being fully updated, family by family, in a massive ongoing undertaking.

We talked about how things have shifted in nature since the last edition 25 years ago, including the dramatic increase of established invasive plants in the landscape. I learned about native geraniums and orchids, and about various surprising relatives of milkweed (including vinca!).

Read along as you listen to the Nov. 26, 2018 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).

taking stock of our flora, with dr. robert naczi

Q. The title of the manual, “The New Manual of Vascular Plants of Northeastern United States and Adjacent Canada.” Oh boy. [Laughter.]

A. Yes.

Q. It’s a mouthful.

A. It is.

Q. Many users know the reference as “Gleason and Cronquist” for its previous editors, but tell us a little about the history of the book and why it’s so important.

A. Sure. Thank you. This book is in a lineage that began at New York Botanical Garden with our Founding Director, Nathaniel Lord Britton. He had a project when he began the garden and he published the first volume of that, the “Illustrated Flora,” in 1896.

When the garden was founded, he finished with the “Illustrated Flora” and then he got the idea: let’s make a condensed version, a one-volume book handy for field use. He called the “The Manual of the Flora of the Northern States and Canada.” He published that in 1901, and in short order, that book went through several editions.

Then, the next thing really big to happen was Henry Allan Gleason, who was a great botanist here and he got the idea to renew the manual series. He teamed up with the younger botanist also at the garden, Arthur Cronquist. In 1963, they published their updated manual. Then, Gleason and Cronquist published their second edition in 1991, and that book has been in press for a while. As we’ve made many discoveries in botany since 1991, the Garden realized we needed to update that and they actually opened the position of Curator of North American Botany …

Q. And here you are. [Laughter.]

A. … and here I am, with the chief duty of writing this new manual. [Above, left to right: Britton, Gleason and Cronquist; NYBG photos.]

Q. Yes. I want to talk about some of the new things that you’re finding out, but first, how do you even do such a project? I mean, I’m assuming that you don’t literally, on your own alone go out and try to count all the plants. And I know there’s other projects like the New York Flora Atlas, for instance, just to name the one in my state or VASCAN, which I think is the vascular plants of Canada. Do you take in data from elsewhere or is it a collaboration? How does it work a little bit?

A. It’s very much a collaboration. We benefit from those resources and we in turn help them, so it’s an ambitious project. We estimate that we have 5,300 species that grow spontaneously or grow in the wild within the region, the geographic region, covered by the new manual. This is a multi-year project and we depend upon resources like the New York Flora Atlas and VASCAN, the vascular plant database for Canada, and many other similar projects. Then, as we write our treatments for every family, those projects benefit from the updated resources we provide on identification, etc.

Q. It’s kind of a two-way street. That’s great, so it’s iterative and collaborative. Yes.

A. Absolutely.

Q. I know you’re not done by any means, but how significant so far … and you’ve done some plant families, you’ve issued these reports on some of the plant families and you’re working your way through … how significant are the changes from that previous edition, which when you began was about 25 years old, that 1991 edition and what are the factors that are causing the changes, do you think?

A. Well, that’s a great question. It’s one near and dear to my heart. The changes are pretty significant, so I did an analysis of the families that we published our first year, and that was 28 of them. Then, I updated that in my second year. By this point, we have 91 families published through New York Botanical Garden Press and what we found is that on average there’s a 21 percent increase in the number of species recognized in …

Q. Wow.

A. … manual treatments relative to Gleason and Cronquist.

You asked about the causes and that’s a natural question. We find that the reasons for these increases boil down to three. One of them is our increase in understanding of the plants themselves, how to classify them. For example, in the past, sometimes we considered one species that we now recognize to be two or three.

Then, another, which actually is the leading cause for the increase, is the introduction of non-natives. Non-native species that have been brought in intentionally or unintentionally, but most often intentionally for gardening purposes and they have gotten loose, so to speak. They’ve become established in our flora.

Then, the third reason is that even though our region is relatively well-known botanically, we still continue to make discoveries in our native flora within this region. That also adds to that total of, as I say, an average of 21 percent increase in number of species.

Q. It seems there’s an increase in our understanding and especially of how to classify, and then there is this infusion/invasion of different plants that just weren’t there 25 years ago or hadn’t taken hold in … become wild. They were maybe still in gardens. If they did exist at all, they were still in gardens. They weren’t a problem.

A. Some were and then actually some have been introduced very recently, since 1991, and taken off …

Q. Really quick.

A. … very quickly.

Q. Really quickly, yes.

A. You’re right, some of them have become invasive, not all, but some of them have become invasive. One of the criteria for inclusion of a species in the new manual is that it must be established in the flora. In other words, …

Q. Right, that’s the word you used, established.

A. Yes. Let’s say one of these species got loose from a garden and was growing 100 away from someone’s property and that’s the only place we know if it and there are only two plants growing there, that’s not really reason for including it because it’s not completely established, it’s not something that an average botanist is likely to run across.

Q. O.K., I see. You mention, of course, a lot of your answer was about invasive plants, but you also mentioned things we didn’t used to know so well. And one of the things we gardeners love to blame you botanists for [laughter]… for everything. No.

A. Right. I’m used to that.

Q. Actually, you can blame us. You can blame us for things like some of the lust after some of the plants that proved invasive, but we can in turn blame you for reclassifying plants and confusing the heck out of us.

A. Right.

Q. That’s that sort of molecular, systematics or whatever, where taxonomists, because they’re able to observe plants at that tiny little level, at the gene level, they can figure out who is really related to who, so they rename them. Can you tell me a little bit about that?

A. Oh, sure. I’d be happy to. Don’t worry, I have a thick skin when it comes to blame for all sorts of things, especially name changes.

Very briefly on that, we botanists see it from a very different perspective, and I like to use a quote from one of the great botanists of this past century, Lincoln Constance from University of California. He called our field of plant systematics “an unending synthesis,” so we continue to bring in data, we continue to learn, we continue to discover and what are we aiming for?

We bring all of this knowledge to bear on improving our classification system. By doing that, it’s necessary to refine what came before.

We botanists see it as a way to improve upon what we’ve been doing all along, but unfortunately, it does mean for the average person, the general public, that there are some changes. There are a lot of name changes recently because with molecular systematics, we’ve been making so many discoveries.

Let’s take an example of some of these discoveries. If you were to look in the 1991 edition of Gleason and Cronquist, you would see two families. The dogbane family, Apocynaceae, and the milkweed family, the Asclepiadaceae. But in the new manual, we’ve actually combined those two families and the name is Apocynaceae when we combine them, so at least it’s one of the names that was out there.

Q. Right.

A. In this case, we’re actually lumping things. We have fewer families, we have one family instead of two. Why do we do that? Because we discovered in our efforts to reflect a long-term change, the phylogeny, the long-term or evolutionary history of plants—in our effort to do that and make a natural classification, that it’s actually more reflective of what happened if we do have the one family, because it is all of the descendants of a common ancestor based on our present analyses. That’s what we’re aiming to do with our modern methods.

That’s one example of a change. Then, we have other examples where the snapdragon family, as recognized in 1991, is now eight or nine families, so it can go both directions.

Q. [Laughter.] Yes, it can. I think it’s harder for me when you make more new ones that I’ve never heard the name of before than when you lump. Then I’m more apt to get it.

A. Well, that’s why I thought I’d start with the lumping.

Q. Right. Tell me the good news first, Rob, right?

A. Exactly, yes.

Q. Well, it’s interesting that you bring up the dogbane family, because when I was reading some of the reports that you have published so far, some of the family reports that you’ve published so far in this effort, and you said you’ve done 91 so far. How many are there going to be total, by the way? [Above, native Apocynum cannabinum; image from Wikimedia Commons.]

A. About 230.

Q. O.K. I was reading some of them, and I don’t have the training, the expertise, the education in this. I’m an advanced beginner or a beginning intermediate kind of person, so I recognize some of it. But what I did get as I read through from family to family was that, that family, the dogbane family, was a good example of also the sort of invasive story. Like, the species that you counted in more than one family report published so far tell the story of this increasing pressure and presence of invasive plants, but that one, the dogbane family, it was like there were some … like Vinca was in it and now …

A. Oh, sure.

Q. … the dreaded swallowwort [Vincetoxicum], which is a …

A. Yes.

Q. … newer, or I don’t know how much newer, but it’s a different type of a situation; it’s not like a garden groundcover. It was an interesting group, and there are also popular plants that we covet and we haven’t been told they’re not a good thing. In fact, some natives, like Amsonia is in there, too.

A. Amsonia, the bluestar, sure.

Q. Isn’t it interesting that in one family they are …? Milkweed is something, of course, all the gardeners want because …

A. The butterflies.

Q. Exactly.

A. Monarch butterflies.

Q. Exactly.

Q. It’s such an interesting family. Now, does Amsonia have that complicated chemistry like the dogbane and the milkweeds?

A. I have to be honest and say I don’t know much about their chemistry.

Q. Yes, I don’t either. It never struck me that way.

A. I’ve not heard about any of our butterflies feeding on them, but I imagine there are insects because most of our plants do support a whole suite of insects, some that are generalists and some very specific.

But Amsonia illustrates, and in some of these others, like Vinca especially, illustrate how plants, we bring them in, they become popular for a while, many of them fortunately remain popular, but then others, like Vinca, they fall out of favor as we discover they have these aggressive tendencies.

Many of our plants that are non-native, we grow them for a while and they seem well-behaved, and they’re going through what we call … what we scientists call a lag phase. They’re building up their numbers, their seeds, in the environment. And then all of a sudden, it seems like they explode in multiple places and become invasive. We have some tools of predicting which species will become invasive.

Q. Oh.

A. We have discovered, we who study invasive plants, have discovered that the leading cause, and I’m sorry I have to break the news to you, the leading cause of introduction of invasives is actually horticulture.

Q. Yes.

A. It’s gardening, because most of these invasives are attractive to us and that is a good thing. They’re beautiful plants, but we should admit it, that’s also the problem. We want them because they’re beautiful, they’re easy to grow, they’re aggressive, they seed easily, but some of those same characteristics are what make them invasive.

Q. Right. As we used to say, we used to call them “doers.” Do you know what I mean?

A. Yes.

Q.  A plant or I would call them confidence-builders, you know, plants that …

A. [Laughter.] Right.

Q. … oops!

A. For those of us that do not have the greenest of thumbs.

Q.  Right and sure enough, that can turn on you and it can turn out it’s a thug, and it can be even worse than that and be something that then invades natural areas, beyond your garden.

A. You’re right, Margaret. This family, the Apocynaceae, the dogbane family, well illustrates what a mix we can have because within the family, especially in the genus Asclepias, the milkweeds, we have a tremendous number of rare species. In nature, many of these plants have very low numbers in each population, yet they’ve supported themselves through the eons. This is just a different strategy for them for living in their populations.

It’s not like the one, the common milkweed, which tends to be weedy and form dense populations, the vast majority of them you’ll find only a handful of plants in the population. Many of them are very, very habitat specific, and they’re incredibly beautiful plants and I hope that they will catch on even more for horticulture. [Above, A. syriaca, common milkweed; photo by Robert Naczi.]

Q. Yes. I was actually surprised. I didn’t know that Vinca and Amsonia were even related, so that was, even again with my relatively limited ability to grasp everything in one of the reports, I learned a lot from reading that report.

A. Well, that’s wonderful. I don’t agree with you that it’s your limited ability, I think it’s just that there is so much to learn. We have so much to learn about our native flora, and every person who has the will to do so, with the manual can really start at any given point. They can jump in on any family.

Q. Well, and there were two other reports that caught my eye. One was the geraniums, the Geraniaceae. I think a lot of people who are gardeners think, oh, perennial geraniums, those are Geranium macrorrhizum or whatever, geraniums that are not from the United States and are not naturalized probably here. But we have in our region, we have a number of both non-native and native species that are in your report, for instance. [Above, G. maculatum from Wikimedia Commons.]

A. Absolutely. In fact, I remember this treatment of the Geraniaceae. We had a number of species that were not in Gleason and Cronquist, like we’d been saying that were non-natives. Then, some others that we’ve learned more about, some natives about which we’ve learned more since the publications of the ‘91 Gleason and Cronquist. You’re right, it’s another good example.

Q. Where I garden, when I first came to the place, there were two. And they were not in anywhere near the same spot and I’ve never … there’s sort of two buildings at my house and separated by a little bit of a distance. In one area grows Geranium maculatum, I think would be the  …

A. That’s what we call wild geranium.

Q. …wild geranium and then, in another area far away from it, Geranium robertianum [below, from Wikimedia Commons].

A. Of course.

Q. They don’t seem to want to be in the same spot, but they’re both geraniums. I guess, now having read the report that you’ve done on geraniums, I learned that maybe there’s some dispute about whether robertianum is actually native back all the way in time.

A. Right. For the longest time, we considered it an introduction from Europe and then, more recent evidence has been accumulating that maybe it had been here all along. Either way, if it is an introduction, it was very, very early, but even its name reveals what a link it has had with our human civilization. It’s named for Saint Robert.

Q. Yes.

A. Most of our plants we give descriptive names to, whether it be some aspect of their appearance or their geography, but in this case, Geranium robertianum. And I had to chuckle because it’s herb-Robert.

Q. [Laughter.] I know, herb-Robert. I know, but you weren’t around when it was named.

A. Definitely not. Thank goodness for that.

Q. Yes. I want to take a couple of minutes to talk about orchids, because again, for a lot of gardeners, they know orchids as a houseplant. Maybe they know [the lady’s slipper] Cypripedium, or maybe they’ve heard of or seen it in a native plant garden one or two examples of native orchids, but really, they don’t know about it. There were a lot of orchids in this report.

A. Oh, very much so. North America and especially the Northeast, the region covered by the new manual has a very rich orchid flora and many genera. And I’m especially excited by this treatment that we just published this year, because we have two lead authors.

The new manual is a collaborative effort, and we collaborate because we benefit from the expertise of people throughout the world. We’ve brought two of the world’s experts on the orchid family, Matthew Pace, who is here at New York Botanical Garden, and John Freudenstein of Ohio State University. They teamed up. And another exciting thing about this treatment is in the last few years, each one of them has been describing new species of orchids. Each one of them has one of the species that they described in this treatment, that grows in the Northeast.

Q. Oh, that’s nice; huh.

A. Yes, it is very nice, so John Freudenstein had a coralroot, Corallorhiza bentleyi, and Matthew Pace had a Lady’s tresses, Spiranthes arcisepala.

Another thing about this treatment is, because of the great interest in orchids, so much has been done on studying the Orchidaceae, the orchid family, that we’ve made all these great advances and this is a treatment that especially reflects that increase in botanical knowledge. Whether it be in the recent discoveries in the field or whether it be in the new names we have for them, whether it be in the new classifications for them, all of those aspects are reflected. Then, there’s a lot of conservation concern, especially as we see many of our native orchids decline.

Then, another thing I like about this treatment is the vast majority, actually all but one, of the species from this treatment are native to the area.

Q. That was what I was overwhelmed by. I didn’t know there were so many. Yes.

A. Oh, it’s wonderful. I really recommend this treatment to everyone.

Q. It was an eye-opener for me definitely. I wanted to ask you about something not related to the manual or the work, the treatments. I know you were a professor for many years.

A. Yes.

Q. So did you ever teach Taxonomy 101 or Plant Systematics 101, beginner botany?

A. I did. I taught Systematic Botany.

Q. I’m a gardener. What a good place for gardeners, my listeners and readers, to start? I mean, are there books or whatever? I know, I see the New York Botanical Garden Adult Education Division is going to offer in the winter its Botanical Latin course again, but are there books, website? Where do we start? Any recommendations or tips?

A. Well, I love your question and being a professor, I love to turn people on to studying, especially plant systematics. If your listeners have a botanical garden nearby that has a public education outreach, almost certainly there will be courses in plant identification, plant systematics, plant diversity. I would recommend those.

If not a garden, then a botanical society or a wildflower society. There are many, many such societies, fortunately, and many of them do have courses.

There are also some wonderful books out there, and some of them can be advanced and some are beginner level, so jump in whatever level’s appropriate. But one that I would recommend as especially excellent is called “Plant Systematics: A Phylogenetic Approach,” and it’s by Walter Judd and his colleagues. Then there are a lot of websites on plant identification, basic principles of classification, and I would enter words like taxonomy, systematics, phylogeny.

I think we have an abundance of resources. Certainly, the human element, botanists that can teach these courses, make it a lot easier for people, so I really do think one of the best ways is teaming up, finding a hopefully local outlet, like New York Botanical Garden, which has a very robust offering of courses in all these subjects.

Q. I’ll give some links to the upcoming courses there and I’ll find some others to augment the transcript, but I’m so glad to speak to you today, Rob Naczi from New York Botanical Garden about this work. Thank you so much for making the time.

about the ‘new manual’ from nybg

‘THE NEW MANUAL’ is being published, family by family, as downloadable pdfs from NYBG Press, each sold individually. More about the project overview is at this link; and detail about the latest treatments published in 2018 (including those in this podcast) is here.

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 ninth year in March 2018. 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 Nov. 26, 2018 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).