a closer look at summer wildflowers, with carol gracie

THE BELOVED WILDFLOWERS of springtime—the trilliums, mayapples, Virginia bluebells—are probably gone till next year, but don’t despair. Here comes the next cast of players, the wildflowers of summer. The acclaimed naturalist Carol Gracie looks beyond their surface beauty in her new book on the subject, into their life histories and even cultural uses of plants like cardinal flower, lupine, milkweed, asters, goldenrods, and more.

Carol Gracie, a former longtime educator at the New York Botanical Garden who also worked for The Nature Conservancy, has followed her own intense curiosity to become a leading expert on wildflowers. Now her second book, “Summer Wildflowers of the Northeast: a Natural History” from Princeton University Press (Amazon affiliate link), forms the companion to her earlier spring volume.

We talked together about all the insects–not just monarchs–who use the milkweed plant in some way (and what they have in common); about a flowering plant with no chlorophyll at all; and even how experts have trouble keeping track of all the asters and goldenrods.

Plus: Enter to win a copy of her book by commenting in the box at the very bottom of the page.

Read along as you listen to the June 9, 2020 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on Apple Podcasts (iTunes) or Spotify or Stitcher (and browse my archive of podcasts here).

summer wildflowers, with carol gracie



Margaret: So I want to start with the same question I asked you when we spoke, I don’t know, a few years back upon the publication of your book, “Spring Wildflowers of the Northeast.” The subhead on the cover of the new book, the summer book, as on the old one, says “A Natural History,” and I’d like to know what that means. Tell people what that means.

Carol: Well, it means looking beyond just the beauty of the flowers, and learning about how they fit into the environment, and what their importance is to insects or birds or other animals, and sometimes to other plants as well. So I’d like people to know how these plants work in the environment, what their roles are.

Margaret: You encourage us, I think in the text, in the preface of the book–you encourage us when we’re looking at wildflowers to almost act as a birder does when watching birds. Yes?

Carol: Yes, I do, because it’s not just checking off that you’ve seen a Canada lily, for example-

Margaret: [Laughter.]

Carol:  …or you’ve seen a house sparrow, it’s really observing what that organism is doing. And there are still things to be learned about even our local wildflowers that have not been observed. Because people just think, well, they’re common; they’ve been here forever;  anything that is known about them must be written already. But yet if you just take the time and patience to sit there and watch, you could discover something new. And you’ll definitely discover something interesting.

Margaret: Your book, in the title, it zeros in on the Northeast, but we should say where that is, because it’s not a small area, “the Northeast,” in the terms of this book.

Carol: Right. Thank you for doing that. I’m using the concept that was used in Gleason and Cronquist, which is the manual for vascular plants of the Northeast. And their concept of the Northeast goes from Southern Canada, down along more or less the Mississippi River, down to Northern Missouri and across into Kentucky and Virginia. So it’s a big area. I’ve had people say, “Oh, I’m from Virginia. I’m sorry, I can’t buy that book because it doesn’t have any of my plants in it.” But these plants are often wide ranging and many of them are in the Midwest and in the Northern part of the South as well. [Map of green coverage area above from New York Botanical Garden.]

Margaret: Right. So for example, one that’s in the book, and I don’t know how you managed to choose, because there’s a lot of plants out there in that regional area that bloom in the summer from early to late, but you picked… how many are there in the book? Are there 30, or how many are there?

Carol: There are more, there are about 35, I think. Or even more than that, because in some chapters I cover many more than one species, a group of related species, for instance.

Margaret: Right. So for instance, you chose common milkweed and there are other milkweeds, but you chose common milkweed [above]. And that is over a far wider range than what we just talked about.

Carol: Oh, it is. Right. And that goes even beyond the Northeast. So it’s an important-

Margaret: Yeah, I think it goes to Texas.

Carol: …plant for many reasons. And I’m sure all of your listeners are familiar with the milkweed-monarch story, but it has many other interactions with other insects in particular-

Margaret: Right.

Carol: …that make it fascinating to me.

Margaret: So let’s talk a little bit about that. The species, so it’s Asclepias…?

Carol: Asclepias syriaca, which may sound surprising because it indicates that it comes from Syria. But in fact, that goes back to a mistake that was made back in the 1600s, when this plant was first brought back to European botanists to describe, and they saw it as being the same as a plant that had been discovered in Syria. And thus, they lumped it into that same species, which was Apocynum syriacum. And when Linnaeus realized that it was a different genus, that it was far different from Apocynum, he put it into a different genus—Asclepias. But by the rules of botanical nomenclature, he had to keep the second part of the name, the specific epithet, so thus it carries on that syriaca in its name.

Margaret: Huh. [Laughter.]

Carol: So it’s a bit confusing, but it’s all very legal botanically.

Margaret: So once you get your adjective, you keep your adjective so to speak, right?

Carol: Yes, you do. Right.

Margaret: So, and you just said it, we all say even uninitiated, non-gardeners and non-botanists, you say milkweed, people think “monarch.” But as you say in the book, it’s actually a guild of insects. You refer to it as “a guild of insects” who appreciate this plant in one way or another. So I thought it’d be just kind of fun to introduce us to some of who you’ve met in getting to know common milkweed better.

Carol: Well, first of all, there is this large guild of insects. It must be a dozen or more different insects that feed upon milkweed in one way or another. And they include not just butterflies and moths, but also beetles and bugs and aphids, and what else? Weevils. A weevil is a kind of beetle.

But they don’t compete with each other. You would think with all of those things feeding on the same plant, there would be a lot of competition. And the reason for that is they either feed at a different time of year, or they feed on a different part of the plant. Some of them feed on roots as larvae, some of them feed on the leaves as adults, and others lay their eggs in the stems. So there are many, many different ways of predating milkweed.

And I think the most fascinating to me is probably the four-eyed milkweed beetle. Because if you look at it closely, which I tend to do when I’m taking my photographs, it looks as though it has four eyes. And that’s because it’s a member of the long-horned beetle group, and those long horns refer to the antennae that they have, which are proportionately long for the size of the insect.

And those antennae are placed on the head so that the eye has a little notch in it that sort of surround the antennae. But in the case of the four-eyed milkweed beetle, it’s so far in, that the eye is split in two. So you actually have an eye above the antenna and an eye below the antenna on each side.

Margaret: Oh my.

Carol: So it’s a strange-looking creature. And all of these insects, almost all of them, have similar what we call warning colors or aposematic colors, that warn predators like birds, for instance, or other insects that they might be toxic, just like the monarch has that bright… well, it’s caterpillar has yellow and black and white, and it’s adult has the orange and black pattern on its wings. [Above, the four-eyed milkweed beetle’s warning coloration.]

And most of these other insects that feed on milkweed are also colored similarly. And they are colored that way because it warns birds, before they try to eat them that, “Hey, think twice; I may be toxic.” It’s a system that has developed over eons that eventually protects most of the insects. There’s always a learning experience for the bird. It may try one monarch and get very sick and learn then not to try others.

But the milkweed beetle, for instance, is red and black, a sort of round leaf beetle that feeds on milkweed is also sort of an orangey-red and black. There’s another, well, there are two different species of milkweed bugs that are red and black. So it’s kind of a theme that carries through with the weevil being the exception; that’s a dull gray. And its protection is just to quickly drop to the ground if something comes after it.

Margaret: Yeah. Bees have warning coloration. I mean probably the most familiar insects, yes?

Carol: Mm-hmm.

Margaret: And again, it’s that black-

Carol: Black and yellow.

Margaret: ...against a bright color, right?

Carol: Right.

Margaret: You might take a bite once, but you probably won’t again. [Laughter.]

Carol: Exactly. Yeah. So some must die to protect the rest. And in fact, milkweed has a variety of percentage of those cardiac glycosides in its sap. So some of them are really not toxic at all. They say maybe two-thirds of them are toxic enough to cause a bird that feeds on a caterpillar or a butterfly to become ill. And the other third is sort of a mimic in a way, in that it doesn’t have enough toxic cardiac glycosides in to become harmful to birds, but it’s protected because it looks just like the other milkweeds.

Margaret: Sometimes I see like a lot of this plant, a lot, a lot, a lot of this plant, it’s a plant that is a robust grower.

Carol: Oh, unfortunately it is. [Laughter.] I speak from experience like everybody else I’ve been doing my best to help monarchs. And they’re telling everybody to plant milkweeds, plant milkweeds. But I have a small perennial garden and my milkweed, which I planted from seed, did well the first year or so, but then by the third year, it had traveled under my stone pathway and come up in an entirely different part of the garden and was spreading all over.

And it took an awful lot of work to dig it out because it’s spreads primarily by underground rhizomes and it’s like tuberous. And then you have to get every bit out, otherwise, any piece that you left will grow into a new milkweed plant. So I still have an occasional one coming up here and there, but for the most part it’s gone.

Margaret: Yeah. It’s a good one to give a space of its own to, I think. Like some of the goldenrods that we can talk about later. And many plants, that they’re more inclined to a wide open space than toward having neighbors in a tightly planned perennial border, or the sort of contrivance of a garden. Sometimes it’s hard to confine them to those spaces, I think.

So one of the most curious plants among those you included in the book is the Indian pipe [Monotropa uniflora, above], and it’s this little creature that’s white. It doesn’t have any chlorophyll, I guess, right?

And I remember the first time I ever saw one in the woods in New Hampshire as a little girl where we went for summers, and I thought, what is that white thing under the tree? Tell us about the Indian pipe. Cause it was a surprise to me that it was in here. Even being a plant person, I think of it as sort of this other-worldly creature.

Carol: Right. Well, I’ve been with many friends who are pretty knowledgeable about wildflowers, who upon seeing the Indian pipe for the first time thought that it must be some sort of strange fungus.

Margaret: Yeah.

Carol: But it’s not. It’s a true flowering plant. As you mentioned, it doesn’t have chlorophyll, so it can’t photosynthesize. It has no green pigment to capture the sun’s energy. And because of that, you often find it in the dark understory of a forest, because it doesn’t need the sunlight. So it’s sort of ghostly—in fact, another name for it is corpse flower, but I prefer Indian pipe.

But it has all the floral parts. If you bend that pipe up and look under it, you can see stamens and a big, wide stigma that takes up most of the space in the opening of the flower. And it’s got the petals, which forms sort of a tubular-like structure and sepals, and it even has little tiny scale-like leaves on the stems. But of course they don’t function the way normal green leaves do.

So because it can’t photosynthesize and make its own food, it has to get its nutrients from someplace else. And this is one of those plants that we now refer to as myco-heterotrophs, which is a very fancy name for a plant that depends upon a fungus as an intermediary between itself and another green photosynthetic plant. In the case of Indian pipe it’s trees, and the fungus in this case is known. In most cases, they don’t know what the fungus is because they don’t often find the fruiting body of it. It’s just the underground mycelia, they’re called, that thread through the soil and connect one plant to another. But it’s a member of the Russula group. It can be either the genus Russula or the genus Lactarius, which are both very common mushrooms.

Margaret: Yes.

Carol: Some of them are really quite pretty. It’s the Russula that I photographed for the book growing next to the Indian pipe has a bright red cap. It’s a gilled fungus. So it’s a very interesting combination, because from the root mass of the Indian pipe, it’s infiltrated by the fungus, which then again infiltrates the root hairs of a nearby tree. So it brings photosynthate carbohydrates from the tree to the Indian pipe so that it can survive. And it also provides the tree with extra surface. The root hairs have a greater ability to pick up minerals from the soil like phosphorus, for instance.

So it’s not really helping the fungus at all. The fungus is I think not really getting anything from this interaction. I may be wrong on that, but it helps the tree and it helps the Indian pipe.

Margaret: So is that a saprophyte? Is that what you call that kind of relationship, a saprophyte?

Carol: Well, that’s what you and I probably first learned when we were learning about plants, they were called saprophytes back in the dark ages.

Margaret: Oh, when we were 29? [Laughter.]

Carol: Right. I know you’re younger than I, but up until not too long ago, these were thought to be saprophytes, which meant a plant that derived its nutrients from the decomposition of material in the soil, organic material, like leaf litter and that sort of thing. And it was only more recently that they discovered no, it’s really this relationship with a fungus. It’s called a mycorrhizal fungus because it grows on the roots.

Margaret: O.K.

Carol: And it’s not just with plants that are achlorophyllous, or have no chlorophyll, like an Indian pipe, but with many, many other plants too, especially others in the blueberry family I might add, which Indian pipe is a member of.

Margaret: Oh, interesting. Oh, O.K. Yeah. I saw another oddball the other day when I took a walk, just a short digression, and I keyed it out. It was just a strange thing, sort of orangey and yellow. Almost at first, the flower had looked almost like a bee balm kind of a thing, but it wasn’t.

Carol: Right.

Margaret: And it was-

Carol: I know what you’re talking about.

Margaret: … a Pedicularis. You know what I’m talking about? Pedicularis canadensis. [Above.]

Carol: Right.

Margaret: And when I looked up, I read it was a hemiparasite, speaking of life cycles and life histories of plants and how they live. A hemiparasite.

Carol: Well, just means that it does have chlorophyll in its leaves. You probably noticed that it has normal green leaves.

Margaret: Yeah.

Carol: So it is capable of making its own carbohydrates, but it has very few root hairs on its roots. So it needs that relationship with something else. It parasitizes up to 80 different or over 80 different species. It’s not very specific. Some parasites are host-specific and will only parasitize one particular plant. But Pedicularis canadensis, which is sometimes referred to as lousewort or wood betony, will parasitize many different plants and get its water and minerals from that source. So it can make its own carbohydrates, but it needs extra water and minerals coming from another plant.

Margaret: Oh, O.K. All right. I loved in the book that you included jewelweed, a native Impatiens, Impatiens capensis [above]. And I always leave a few patches. It self-sows around the garden, and I always leave a few areas despite the suffix -weed in its common name. And I read in your book that “the seedlings germinate synchronously in spring.” And I just noticed that outside recently. So they literally like all come awake at the same moment and the same size and-

Carol: They do. Yeah, they just cover vast areas of usually sort of low, wet ground. And therefore they out-compete anything else that be coming up at the same time because of the shade that they produce. And not all of them survive, otherwise you would have a tangled mess of plants. But those that are the fittest will survive and you’ll have a nice clump of jewelweed there.

Margaret: Yeah. What a genius-

Carol: Which I always used to enjoy when I taught children, because they loved popping the fruits and having the seed shot out. But I find that adults, like it just as much. [Laughter.]

Margaret: It is fun.

Carol: It’s a fun plant to talk about when I do field walks for adults as well.

Margaret: Yeah. So we have-

Carol: And the seeds are edible as well. I compare them a little bit to black walnuts in taste, but of course it takes a handful to make it worth eating. So you have to hold the fruit carefully in your hand and capture the seeds in your hand so that they don’t go shooting off a few feet away and then you can eat them. And they’re one of the most beautiful seeds, because if you peel off the outer brown seed coat, they’re an absolutely beautiful turquoise blue or robin’s-egg blue, perhaps.

Margaret: I saw the picture in the book and I had never seen them that color. So then this year I’m going to have to try to grab some before they fly around and before they go “boing.” [Laughter.]

Carol: Yeah, just peel off or scrape off with your fingernail, that outer covering.

Margaret: Yeah. I think of them as sort of late summer wildflowers of all the goldenrods and the asters [above], with both of those, and you have a lot about them in the book, but I have to confess, I get overwhelmed. And you know, to me the goldenrods, it’s like sparrows—I know it’s a sparrow or a goldenrod, but I’m not sure which one, and the same with the asters.

Carol: [Laughter.] Right.

Margaret: It made me smile, not really [laughter], that there’s no longer technically any member of the genus Aster in Northeastern North America. Right? They’ve all been renamed.

Carol: That’s true. In fact, the names are actually the old names that they had a long time ago before they were lumped into the genus Aster. There are asters in Europe, in particular, and in other parts of the world, but all of those in our country have been segregated into one genus or another. Sometimes it’s dependent on the shape of the bracts, or the involucral bracts, I should say, under the flowerhead, or the type of hairs, or a lot of very minor characteristics. So they’re still commonly called asters, but scientifically their names have changed. And you’re not alone in being confused by them. I put myself in that category. [Laughter.]

Margaret: Yes, yes.

Carol: As you may read in my book, Asa Gray, who did the early treatment of asters was befuddled by them at many points and almost willing to give up, but he pursued and eventually finished his research.

Margaret: I think you excerpted a little note, he wrote to someone else saying, “If you find me in the loony bin, it’s because of the asters.” [Laughter.] A kind of character. Well, I’m having a lot of fun with the book and I’m so excited, Carol, that it came out, “Summer Wildflowers of the Northeast: A Natural History.” I’m so glad that it came out right now, because especially with so much time being spent at home this year, I can be outside with it and really look more closely, thanks to your insights. So thank you so much for taking the time.

more from carol gracie

I’LL BUY AN EXTRA COPY of Carol Gracie’s “Summer Wildflowers of the Northeast: A Natural History” (Amazon affiliate link) for one lucky reader. All you have to do to enter is answer this question in the comments below:

Are any native American summer wildflowers a part of your garden?

(I have a lot of asters and goldenrods in the later summer into fall, a little milkweed, Joe-pye weed, patches of jewelweed, and various Rudbeckia that might be native slightly outside my region, among others.)

No answer, or feeling shy? Just say something like, “Count me in,” and I will, but sharing an answer is even better.

I’ll pick a winner after entries close at midnight Tuesday, June 16, 2020. Good luck to all.

(Disclosure: As an Amazon Associate I earn from qualifying purchases.)

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 11th year in March 2020. 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 June 8, 2020 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify or Stitcher (and browse my archive of podcasts here).

  1. margaret says:

    AND THE WINNER IS: Kate Kruesi. Thank you all for such enthusiastic response and sharing your stories. More native plant podcasts to come!

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