Gardening Unplugged - Ex situ Conservation

Gardening Unplugged - Ex situ Conservation

with Dr. Patrick McMillan

By Published September 14, 2022

Shop for Baptisia at Plant Delights Nursery

In this episode of Gardening Unplugged, recorded on July 22nd, 2022, our Adjunct Horticultural Consultant, Dr. Patrick McMillan, discusses the importance of the ex situ (off-site) conservation.

Gardening Unplugged are free classes presented by JLBG/PDN staff during the Garden and Nursery Open House days. These are 15 to 30-minute discussions walking through the gardens, focusing on seasonally prominent topics, plants, and garden design ideas.

Here are the rare, endangered, and ex situ plants that Dr. McMillan mentions in this video, some of which can be found at Juniper Level Botanic Garden.

  • Schwalbe americana (American chaffseed)
  • Franklinia alatamaha (Franklin tree)
  • Baptisia arachnifera (wooly wild indigo)
  • Spigelia alabamensis (Alabama indian pink)
  • Spigilia gentianoides (purpleflower pinkroot)
  • Clematis socialis (Alabama leather flower)
  • Forestiera godfreyi (Godfrey’s swampprivet)


Video Transcription

I'm Patrick McMillan. I'm the director of the gardens here at Juniper Level Botanic Garden and we're here today, we're going to talk about ex situ conservation, which is a big thing for us. And we'll try to do some of this in the shade and then we're going to move out so we're not burning ourselves up to actually look at some of the really the rarest plants that we have in the garden that are incredibly important from a conservation standpoint. So, let's move a little bit over into shade for just a second while we're talking.

What is Conservation?

All right, so conservation. When you think about conservation, you might think strictly of conserving habitat out in the wild. But you might also immediately start to think about things like panda bears or other endangered species like Siberian tigers at zoos. And zoos have played a really critical role in conserving biological diversity in a world that's rapidly changing, not just climate wise, but in terms of the amount of available habitat. And so, botanical gardens really can be thought of as repositories for genetic information. And in the same way that the zoo is a collection of animals, a botanic garden is really a zoo for plants. So, one of the big differences between a botanic garden and a garden you might have at home, a pleasure garden, or a park, is that we keep very detailed records. We have this guy Zac who keeps really detailed records of where the plants came from, where their origin was, as far back as we can push it to the wild and what's happened to it since that time in the garden. And so we go through all the same things that a zoo might do but instead of a zoo that might have 100 or 120 different types of large animals, here, we have 30,000 different taxa of plants, okay.

Ex situ versus In situ Conservation

So, the one of the biggest sort of controversies in the ex situ conservation, I guess we should say what's ex situ. There's in situ and ex situ. So, in situ means you're preserving that plant where it grows in its natural habitat in the wild, okay. Ex situ means you've taken that plant away from its site, ex situ, and you brought it into cultivation, okay. Now plants that are in cultivation do... they are exposed to different types of selective pressures. Meaning, in the wild, they may have to establish without irrigation. In the wild, they may not have perfect drainage or perfect growing conditions for what they're doing. But in the garden, we can provide them with all of that so we end up getting a lot more survivalship, survivorship, on a lot of species when we're propagating them and that can be good, but it also can tend to change populations over time. So, we really track two different things in ex situ conservation. We track the clone, or clonally propagated plants, which are clones of that exact genetic information. And then we also track those that we have allowed to be pollinated. So openly pollinated or directly pollinated plants and the maternal lines from those where they came from. And that's a way for us to get at what type of genetic information is in the plant and really be successful in being a place where if plants go extinct in the wild, they still have an opportunity to be reintroduced.

Preserving Genetic Diversity

Schwalbe americana by unknown photographer -, Public Domain,
Schwalbe americana - public domain image

So, at the South Carolina botanical garden, where I came from, we did a lot of this. And one of the most interesting examples I like to give to people about how important in allowing botanic gardens to have and practice rare plant conservation is that I was sent a pack of seeds that was collected right before hurricane Hugo from Charleston County, South Carolina of a plant called Schwalbe americana. It's American chaffseed and it's one of the ugliest plants on planet earth. Nobody would ever want to grow it in the garden. It's a parasite on grasses and asters and silk grass, pediopsis, and it has also declined more precipitously than just about any other plant in the East Coast. So, it used to grow from Long Island, New York all the way to Florida, all the way west to Louisiana. Today, it's only found in just a handful of those states and the majority of the populations that are left today are in South Carolina. The plant needs frequent fire. So, hurricane Hugo hits in 1989. September 6, 1989, hurricane Hugo comes through and one of the largest populations this plant is Allendale, at the ball field in Savannah which literally was a ball field where kids used to play baseball. One of the foresters had the foresight to collect seed from that population before the hurricane. It was actually in 1986. He sent it to the New York botanic gardens who had... one of the conservationists there had it in his desk drawer for all those years and in 2017, sent it to the South Carolina botanic garden. In the meantime, that population was hammered by hurricane Hugo. All the trees came down, a big fire ripped through all the slash, and then they went in and did salvage logging and, needless to say, the population was extirpated, okay. Those seeds which should not have come up, had a hundred percent germination when we germinated them in the greenhouse. Every little seed, and these things have tiny little seeds, germinated and we were able to make thousands, and thousands, and thousands of first-generation progeny from those seeds that were collected from wild plants. And those plants ended up being transplanted back out into the Francis Marion National Forest successfully. And now, not only do we have that plant growing where it used to grow, but we have the genetics of the same population and were able to be put back into the same place by thanks to the help of a botanic garden. And we do that kind of stuff all the time.

Turning Backyards into Genetic Repositories

The big struggle that I see in the botanic garden community is - who should have access to these plants, okay. So, there are, like with the zoos, you know, AZA. If you're AZA accredited, you're going to have access to a lot more endangered animals than if you're not. And the unfortunate thing is what it takes to be seen as part of that community that shares endangered plants one garden to the other is restrictive and really only allows huge botanic gardens with big budgets to effectively participate. So, my opinion is that the more people that are growing these things the more we share them widely the more the more ability we have to preserve those things long term. And we can see that with plants that have gone extinct in the wild like Franklinia alatamaha. It's a big, beautiful tree. We’ve got one right by the waterfall on Mount Michelle and it's like a native camellia tea tree. Found by John William Bartram in Georgia on the banks of the Altamaha River. Sold by them in Philadelphia, maintained in gardens in Philadelphia and England and around the world, and now extinct in the wild. And the only reason we can gaze upon that plant is [that] somebody had the foresight to bring that into and commercialize that plant, even, and that's why it's still around. So, you know we have so much of our of our biota that is threatened today and not all of it is federally endangered or threatened but it's just disappearing and so much change that I believe that if we don't start using our backyards also as repositories for that genetic information that we will end up losing a lot of things. And regardless of how much selective pressure has been removed from it, the genes are still there. So, I’d rather have something like that than nothing at all as long as it's legally and ethically maintained and introduced into culture.

From Roadside to Botanic Garden

So, let's take a look at a few that we got in the garden that are really very interesting plants. I'm going to start with one that I think is one of the greatest, it's one of the best horticultural plants for the southeastern US that I know. And the genus that Plant Delights Nursery and Juniper Level are known for... Baptisia.

So, this is this incredible looking thing with this gray foliage that looks more like, in foliage, looks more like that it might be a eucalyptus than a bean plant. This is Baptisia arachnifera which is only found in a couple of counties in southeastern Georgia. It grows in really dry sand hill conditions there and never looks as good as this plant. Most of them that you see in the wild will be similar to one branch of this beautiful thing that is here just enjoying being at Juniper Level. Well, the thing about this plant is, in the wild, the populations are almost all roadside today. They’re just scattered along the roadside through the sand hills that have been fire suppressed so the good habitat's gone, and you have fragmented small populations left, mostly roadside communities. And it thrives in cultivation in the Southeast. And not only does it thrive, it has a huge horticultural merit. I mean, who doesn't want a big gray fuzzy ball of eucalyptus looking foliage that puts out these spikes of beautiful yellow flowers at a time in the summer when everything else is done or in between. Your, you know, July blooms in our southeastern gardens are coveted because you know it's just the time of year that seems to be between the big bursts of color. So, it has everything we want; great foliage all year, nice flowers, a burst of color and it requires no additional water. Like, you can grow this plant without additional irrigation which means, this plant is also resource neutral in the landscape. It supports native pollinators. It supports a native moth, genista moth, which sometimes can defoliate your beautiful baptisia plants. But yeah, a great candidate for everybody to grow but unfortunately not available to everybody.

So here at Juniper Level we have all but one of the world's species of baptisia growing and this one, which is federally protected, cannot be shipped across state lines without appropriate permits and those permits are very difficult to obtain so it's unfortunate for the horticultural community. But the argument against moving around this plant is that you might accidentally introduce it somewhere where you might think it's native and fool all the conservationist into thinking there's more populations of it than there should be, or you also might be making inner generic hybrids you might hybridize with another baptisia and dilute the gene pool or change the gene pool of other species. So those are definite concerns, but the bigger concern is every year that they spray roundup or mow those roadsides which always have signs that say do not mow. And we just visited a schwalbe site down in South Carolina the other week. Big signs - do not mow may through august. Mowed in May, mowed again in June, right. So, these plants that are really working on the edges I think there's a fabulous place to conserve them in the garden and since it doesn't bloom at a time of year when most other baptisias bloom, very unlikely to hybridize or cause any problems with genetic pollution.

Let's take a look at another one down here. It doesn't look like, it doesn't look like much now but if you had been here a couple weeks ago, you could have seen this incredible clump of this very rare Spigelia alabamensis. And it's related to our pink root or Indian pink is what we used to call the plant. Anyway, which was called pink root or Indian pink because the Native Americans would use the root of this plant as a vermifuge which means gets rid of worms. And it was used so extensively for that that even the common species of Indian pink was reduced to near extinction at the turn of the 20th century. So, this one, a recently discovered species from... endemic to little glades along rivers in Alabama it produces these incredible pink flowers in June and July. It's an incredible garden plant. Again, one that is native, supports native things, but one that is also endangered so only available to sell within North Carolina and not shipped across state lines.

Yeah, we have a Spigilia gentianoides. That's also rare and endangered which grows too well. So, some of these things that are endangered in the wild are simply persisting where they can. They don't get the encouragement that they do in cultivation and when you put them in cultivation sometimes, they become weedy.

Clematis socialis
Clematis socialis - Juniper Level Botanic Garden

So, we're interested in really being a repository for genetic diversity and that genetic diversity doesn't have to be beautiful. We certainly have a lot of rare things here that aren't gorgeous. This really interesting clematis. This is Clematis socialis. It's also a native of Alabama and restricted mostly to roadsides these days. Fence lines is where it was actually discovered. Beautiful little bell flowers and this, unlike a lot of other clematis, this clematis doesn't form really long vining stems. It has short stems that just sort of trail. It comes out and flowers in profusion in April and May and then the stems sort of die back. You can cut it back and it'll come back and flower again. It's just another example of a plant that is great in the landscape. Has lots of uses here in the piedmont but again, almost completely unavailable in the trade because it's also a federal protected species. So, lots of examples of that. Now i don't want you to think that's just that ex situ conservation is just... we're just interested in conserving something like this that's federally threatened or endangered. It also goes down to preserving cultivars. You know, if you think about the work that people put through, put forth, to develop some of the standard cultivars that have been used for hybridization and selection since that time. Those older cultivars a lot of times will disappear. And then later on when trends change in what we're interested in, in horticulture, we're no longer interested in big, tall floppy day lilies we want something that's stout and short. Well then, we need to go back to those original genetics to do that breeding. And so, gardens like Juniper Level don't just conserve rare and threatened and endangered things but just simply conserving as many of these cultivars and as many of these plants that are really great in the landscape is really important too. And it's certainly not all North American natives we have we have rare plants from all throughout the world that all find a home here and all get shared as widely as we're able to share them with other people.

Any questions?

None so far.

All right. Any heckling? He's got nothing.

No, no, I can't argue with that.

Schwalbe is a very ugly plant. It's one that's not even ugly enough to be cute. It's just in that pure ugly zone. Yeah, yes but we grew a lot of them in South Carolina.

It Takes a Village - Ex situ Conservation in Action

We actually introduced, you know, talking about climate change and stuff like that. Down on our coastal plain we have this plant uh called Forestiera godfreyi, it's a shrub. We grow some of the ones that that we propagated in South Carolina here at juniper level. But this forestiera has male and female plants and all their populations that are growing in South Carolina are found on Native American shell mounds and rings. So, they're in the salt marsh but just above the salt marsh growing on oyster shells. So, they need that high pH soil, and most populations are one or two genetic individuals, and some populations are just male some are just female, and some have male and female. And the problem we're having in South Carolina is the more frequent we get hurricanes and the higher that the sea level becomes, because even though we've had only a little over an inch of sea level rise in the last hundred years, that inch when you're  you know growing a foot and a half above sea level translates into being inundated when we have a nor'easter or when we have a big hurricane or tropical storm or anything that causes the storm surge to come up. So, we started to lose those populations because they were growing so low down on the midden and a couple of them were, we lost males or females. So, we ended up taking cuttings, the long program we did with the US Fish and Wildlife Service and South Carolina Department of Natural Resources. They sent us cuttings from every existing population. We rooted all those cuttings, kept them distinct male and female segregated, and where they came from. And then when we needed to boost a population, we could move those plants in and that's exactly what they did last fall. And now Forestiera godfreyi has a much brighter future in the wild in South Carolina thanks to the help that came from botanic gardens. So that's part of the magic of what makes that work is finding that connection and mutual respect for horticulture and conservation science. Because we don't do conservation genetics all day but a conservation geneticists does. We grow plants all day. Conservation geneticists doesn't grow plants so when they attempt to... it's a lot of times not as good of a success as allowing someone who has that skill set to work together and cooperate to reach a common goal. Which all of our goals are let's keep these things around and keep them keep them wild.

Cool. Alright, thank you.

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