Apricot, Honey, and Sunshine: Breeding a Hardier Tea Olive
Host: Dr. Ping Yu, UGA Department of Horticulture Guest: Dr. Lisa Alexander, Research Geneticist, US National Arboretum, USDA Agricultural Research Service Producer: Rich Braman Episode: S02E10, Blooms and Beyond, Season 2 Duration: 52:55 Air Date: September 13, 2026
Welcome
Ping Yu: Hello, everyone. Welcome to the Blooms and Beyond podcast, a podcast that uncovers plant history, culture, and management through the lens of science. I’m your host, Ping. How’s everyone doing today? I am doing great because here I have one of my colleagues and my dear friend, Lisa Alexander, on the show today to share her horticulture journey with us, and more importantly, the osmanthus. Lisa has been working on ornamental breeding for years. We share one common interest, Osmanthus fragrans, which is another of my favorite plants that reminds me of home.
So I don’t wanna steal any more thunder from our speaker today. Let’s just jump right into it. Without further ado, here is my conversation with Lisa. I hope you enjoy.
Meet Lisa Alexander
Ping Yu: So hi, Lisa. Welcome to the podcast. But first, let’s start off with the introduction. Can you tell our audience a little bit about who you are and what you do?
Lisa Alexander: Sure. Thank you for having me, Ping. I’m Lisa Alexander. I’m a research geneticist at the US National Arboretum, which is part of the Agricultural Research Service. And the National Arboretum is where science meets beauty, and it is a wonderful place to be. I run a breeding and genetics program that’s focused on ornamental landscape plants. I have a breeding program for hydrangeas, for tea olives, for other woody ornamentals, very much traditional breeding. And I also do genetics and genomics work just to support long-term breeding strategies in ornamentals.
I grew up liking plants. My background is mainly in forestry, but when the ability came open to breed plants at the National Arboretum, since I had a background in woody plants and trees, it seemed like a really good fit, and it supports the nursery industry in my home state of Tennessee. So that’s kind of how I came to be here and to get involved in tea olives.
East Tennessee and the American Chestnut
Ping Yu: That’s great. And you kind of briefly touched base on the story of what brought you in horticulture in general, but can you share us a little bit about from that route what first sparked your interest in plants? I know you grew up with plants, and can you share a little bit more of your journey that leads to your current role as a researcher in horticulture?
Lisa Alexander: Sure. Absolutely. Well, growing up in the Ridge and Valley of East Tennessee, it really sparked my love for forests and nature, and through that, the plants that lived there. So that was, you know, my first love for plants, were the ones growing in the hills and valleys where I lived. It was later on in college when I started working with American chestnut trees that I started thinking more broadly about growing trees, about breeding trees, and that trees could be a crop, and that really sparked my first interest in horticulture.
Ping Yu: So you said your first degree is in forestry, right? Or your second degree?
Lisa Alexander: Yes. Yep, I have an undergrad in biology. It was a very basic biology program, but I did have an opportunity to do a research program with a chestnut breeder, and that really sparked my interest.
The American chestnut tree is my favorite plant. It is such an iconic species for the eastern US, and it was my introduction to all the puzzles of inheritance, and the ideas of plant breeding for resistance. It really sparked my imagination about, you know, what is genetics? What is DNA? How does it relate to all of this? And at the time, sequencing and molecular markers were just in their infancy, so it was such an exciting time to be thinking about plant breeding.
And then chestnuts are so tasty. So it was the perfect… You know, it was this perfect crossover for me between forestry and, you know, this iconic forest tree, and also chestnut production and tree crop production, and also just chestnut culture, eating, growing, and enjoying chestnuts.
A Tree That Supported a Way of Life
Ping Yu: Yeah. So you kind of shared, I guess, chestnut tree is your favorite plant. Is that because it all kind of opened your door to the whole new world for you? Or are there any special characteristics of this plant besides that?
Lisa Alexander: Well, how many hours do we have?
Ping Yu: [laughs] We have one hour, [laughs] we have one hour in total.
Lisa Alexander: Short answer is yes. There are so many special characteristics of the American chestnut tree, the most important of which is it was the underpinning of an entire economy and an entire way of life.
In the mountains, the lumber was strong and rot-resistant, so you could build houses and fences and barns out of it. The mast, or the fruiting crop of the chestnut tree, was enough to support pigs, which were the main animal that was grown, or raised in that region. And then the chestnuts themselves were eaten or used to make flour. So you could essentially live rurally in the mountains just off the provisions of the American chestnut tree.
And so when chestnut blight came to the eastern US in the early 1900s, it didn’t just wipe out a tree, it wiped out an entire way of life. And to imagine that one species could support all that is just amazing. And also the size of them, I can’t help but love big trees. Who doesn’t?
Ping Yu: Yeah.
Lisa Alexander: And so, the fact that the eastern forest does not have trees like that today is, really intrigues my imagination about that tree.
Ping Yu: Yeah, I totally agree with you. Who doesn’t like a big tree? I mean [laughs] they are just gorgeous.
Lisa Alexander: Yes.
What Brought Lisa to Tea Olive
Ping Yu: So what brought you to tea, a sweet tea olive?
Lisa Alexander: Well, what brought me to tea olive was when you are establishing a breeding program, when one is thinking of all the wonderful species out there one could work with, there needs to be a diversity of plants in the program. A lot of the plants I work with are in very short cycles. They’re intensive, or they require a lot of genetic work, or they all bloom in April and May. [laughs] So I specifically wanted a plant that I could have a more traditional breeding approach with. Also, that did not bloom, was not a summer bloomer, which is the time that most of my other crops bloom, and that did not have as big of a footprint in the US already, so that, I don’t know, I had an opportunity to enter on the ground floor.
Also, a former ARS researcher, Donna Fare, was a big fan of osmanthus, and she had me smell a branch, and that… I mean, I think that really wins you over. There’s no smell that is like a mix… What do they say? Apricot, honey, and sunshine. It’s like nothing else. And so I like trees, and so I was immediately taken with it.
Ping Yu: Yeah, I totally get it. Like, if you haven’t smelled a tea olive, or Osmanthus fragrans, get one smell, and then you’re gonna not get rid of it for your rest of life, ‘cause that, that smell just reminds me of home. Because like you said, the US doesn’t have a huge germplasm compared to China because I think China has been cultivating this species for over 2,000 years. So they have a long history about this tree, and that’s the root for my home country. So that’s another reason why I love this plant in general.
Osmanthus in the United States
Ping Yu: But what… Can you share a little bit about, like, history and culture here in the US with Osmanthus fragrans? ’Cause they… Well, I know that they are originally from China, but can you elaborate us or educate us the history of osmanthus growing in the US?
Lisa Alexander: Sure. Well, like you said, in Asia or… Osmanthus are native to all over Asia. Osmanthus fragrans is native to China, and as you said, have been cultivated for over 2,000 years. They’re parts of poetry, art, folklore. Because they flower in fall, they’re part of your autumn festivals, osmanthus cakes, osmanthus wine. I just, I love all the things that, especially China does with osmanthus.
And although Americans don’t have those same centuries-old traditions, we have been growing osmanthus for a long time. They came into this country in the 1700s and 1800s, during, you know, the great age of plant explorers and plant exchange. Both Osmanthus fragrans, Osmanthus heterophyllus, Osmanthus armatus were brought in from Asia. Robert Fortune, a famous plantsman, brought in a naturally occurring hybrid between Osmanthus fragrans and Osmanthus heterophyllus, and we call it Osmanthus × fortunei after Robert Fortune.
Ping Yu: Mm-hmm.
Lisa Alexander: So we’ve grown them for a while. Especially in the southern US, there’s more of a culture for growing it, using it in landscapes. Nurseries will highlight it as four-season charm, a plant that brings both beauty and fragrance. It has landscape appeal. It can be valuable as a broadleaf evergreen shrub, a small tree. It’s often used in verges, like roadside verges. You can drive around New Orleans, for example, and you can see osmanthus growing in verges.
It’s very versatile. It can be a tree or a small shrub. It’s drought-tolerant, low-maintenance, and some of the traditions and cultural uses are growing here. It’s being used in teas, perfumes, gardens. And so it’s really being promoted, I think, by nurseries, especially as a landscape plant. But as that is growing more, all the other advantages and cultural uses are growing as well.
How the Cultivars Differ
Ping Yu: Yeah. Yeah, I agree. And then just to clarify that osmanthus, in general, they have different types based on their bloom time and their habitat. And normally when you brought up the full season long bloom and beauty, there was a specific category or a group of the osmanthus, it’s called… Well, in China, we call it Sijigui, means seasonal long osmanthus that will bloom over the year, if the environmental factor favors their bloom. And there are, for the rest of three other groups, they only bloom in the fall.
And for the color, I think one of the… Anyone who is out there who has seen Osmanthus fragrans, they would be so charmed by the orange or the red osmanthus, that’s, that’s called the Jingui group, which means golden osmanthus [laughs] or gold color osmanthus.
But we just have so many different species. And about how do you… Well, I guess, how do the different cultivars of Osmanthus fragrans varies in their fragrance, bloom season, and growth habits? Can you give us a full picture?
Lisa Alexander: Yeah, no, one of the most exciting aspects of Osmanthus fragrans is that there is so much diversity in those traits that you mentioned. Those four categories, I find them a little confusing, even as an osmanthus breeder. But I think what you mentioned are really the salient points, in that some of them have very creamy white flowers that are appressed to the stem, whereas some of the flowers are much longer, the stems and peduncles are just much longer on the flowers, so they seem more pendulant. There are differences in the color from sort of creamy white through light yellow to bright orange.
And then the most important is the bloom time. So, the very bright one that blooms in fall only, we would call aurantiaca. And the one that blooms fall through the winter and into spring, we might call sempervirens or, you know, all season. And there are a few that are in a more disjunct sort of subspecies that are only spring blooming. So really there’s a huge variation.
And then you have the form. So Osmanthus fragrans are understory trees. They’re native, you know, to temperate forests in China. And so they have the typical growth pattern of an understory tree where they’re gonna… They can exist as a multi-stem shrub very happily, but in the presence of light, there is apical dominance that will take over, and they will shoot up, you know, to try to get the understory light. So, you know, some are more shrubby than others, but all of them have that multi-stem shrub, tree form growth habit, and all are very versatile in that they can be trained up to tree form. They can be a shrub. It just sort of depends on how, you know, you want them to be shaped.
Ping Yu: Mm-hmm.
Breeding Goals for a Hardier Tea Olive
Ping Yu: What is your research or breeding program focused on for the tea olive? What traits that you’re looking for specifically in the breeding line?
Lisa Alexander: Yeah. So we’re focused on crossing Osmanthus fragrans with more cold-hardy species. So mainly Osmanthus armatus, heterophyllus, some of the fortunei cultivars, and trying to recover three main things: the upright tree form, the flowering fragrance, and the smooth leaf form of the Osmanthus fragrans. Many osmanthus cultivars have a holly leaf shape, and that’s a little less friendly in a garden than the smooth leaf. So that is what we are trying to do.
And because we know Fortune’s osmanthus, the natural hybrid between fragrans and heterophyllus, is intermediate in many of its traits between the parents, you know, we feel strongly that hybrid breeding is a good avenue forward to introgress traits between the species.
Compact Plants and Unpredictable Offspring
Ping Yu: Yeah. And another aspect or another trait that people are looking for is a more compacted form, not just for osmanthus, but for a lot of plants in general. Are you also looking at that aspect?
Lisa Alexander: Absolutely. [laughs] We have a great team of cooperators that are helping us evaluate those plants. As you know, when you breed very heterozygous crops like osmanthus, these crops are outcrossing, they’re not inbreeding, so there’s a lot of diversity in all of these plants. So their offspring can be… You cross two medium-sized parents, and you get everything from a tiny dwarf to a giant tree. So it’s really interesting to see what some of these hybrids look like, and to take some of the compact ones and to see, you know, do they retain that compact shape?
People want potted plants and plants for smaller gardens. So it could be that some of our plants, we want them to be cold-hardy, but even the ones that retain, you know, their usual hardiness could have a role as a compact plant in more traditional osmanthus environments.
Ping Yu: Yeah, I think one of the intriguing parts of breeding is that you never know, like, if you’re doing the crossing, you know the parents, but you never know what their offspring would look like. It’s kinda like you’re making kid, and you know what you look like and what your husband look like, but you cannot precisely predict what your kid would look like. So that’s kinda fun part of that.
Lisa Alexander: [laughs] Absolutely.
Why Osmanthus Is Hard to Breed
Ping Yu: What is the, well, most challenging part when you were working on tea olive over the years?
Lisa Alexander: So osmanthus is a tree, so it has all the challenges of breeding a tree, and it has some unique challenges. So like any tree, you just wish it would grow and flower faster. You make a cross, and especially if you’re interested in floral traits, it might take you several years to evaluate that cross. And so just the pace of it, you always wish was faster.
Another one is just the amount of germplasm. So one of the first things we want to do as breeders is to collect as much germplasm as we can and evaluate it. And because most of the Osmanthus fragrans is in another country, it’s just a little bit of a slower process to get those plants in people’s hands to look at them.
Now, that said, I have to make a big shout-out here to Ted Stephens from Nurseries Caroliniana. Yes. Also to Dave Creech, Richard Olsen, Donglin Zhang, and all of the folks that have really made efforts over the years to go to China, to go to Japan, to go to these places, make relationships, and bring plants back into this country. They’re the only reason we have them here. And so they really laid the foundations, and so I feel like thanking them now. You know, your efforts are coming into fruition, and we appreciate them.
And so now we just want more, because when you look at the literature published in China, you can see there are hundreds and hundreds of cultivars, not to mention the natural populations. So just forming the relationships and pipelines to get the germplasm exchanged between countries is challenging.
And then another challenge, as I mentioned earlier, Osmanthus fragrans often keeps male flowers and female flowers on different plants. And so you might bring in 10 plants and realize they’re all males. [laughs] And so that’s very tough on a breeding program. And so to just get more germplasm that has been characterized for breeding, that’s the challenge.
Other challenges include the fact that osmanthus is a one cross, one seed plant. So if you breed hydrangea, you put pollen on a flower and you can get a hundred seeds out of that fruit. Osmanthus has a four-chambered ovary, but only one ovule will be fertilized at any time. It’s the same system as an olive. So yeah, one cross, one seed. And so we have some strategies and tools to overcome that, but I would say that those are the main challenges.
But they’re also the main opportunities, because of that, not many people have gone down these avenues, and so they’re still open, you know, for us to explore and us to pursue.
Ping Yu: Yeah, I like your perception on that. It’s challenging, but also opportunities for us to dive into it and get more discovery from that avenue. Um…
The Germination Puzzle
Ping Yu: I personally have worked on osmanthus, and you… We shared some information already. One of the things that frustrates me the most, or frustrates you even more as a breeder, is the… It’s so hard to let them, like, germinate from the seeds. Even though you can get some seeds, like, from online… But it’s so hard to get those seeds germinate.
And just imagine if you can find a way to have those seeds germinate, those are open-pollinated seeds, how many different, like, traits or characteristics that the new seedlings will come and give it to you and for you to evaluate. That would be… If we could somewhat overcome that, that would open another big door for us or for any breeder that works on osmanthus, right?
Lisa Alexander: Oh, absolutely. I mean, that is one of the main things we’re focused on. Propagation, I think, is one of the toughest issues for osmanthus. And frankly, one of the reasons why it hasn’t penetrated into the American markets further is because you have to propagate the plants for it to, you know, for that to work. And, you know, some very, very specialty operations might graft a few cultivars, but that, you have to have seedling rootstocks to graft. So propagation is so tough. I know that both of our research programs are trying to tackle those challenges and provide good solutions to growers.
Semi-hardwood cuttings are probably the most popular way to propagate osmanthus cultivars, but there are problems of both take and survival of rooted cuttings. Seed propagation is tough because of both the time to germination and the low germination rate, and we’ve tried all different methods. We’ve tried imbibing the seeds, and cold and warm treatments, and hydrochloric acid, but we have yet to hit that sweet spot of both timely germination and uniform germination, because it really needs to be both.
And interestingly, the best seed germination I’ve ever seen was from growers that had fruit-producing trees outdoors in a campus, and they simply let the fruit fall, let it do its thing over winter, and then went back and dug up seedlings in the spring. Now, obviously, that doesn’t scale up. That’s not gonna be a solution for large-scale production.
But what it does indicate is that these seeds really want to germinate in their natural conditions. You know, we have not domesticated them. They’re not wanting to germinate on our timetable, and so we’re gonna have to think about their physiology and mimic that in a way to really get germination protocols for this species.
Scaling Up the Seed Experiments
Ping Yu: Yeah, that’s interesting because I have… Not seen… Well, there’s only one paper that indicated a pretty good germination rate from the seeds, but only one, and it’s from I don’t know how many years ago, and I think that would be interesting to see and how we can work on that.
Lisa Alexander: Well, we are, we’re working on it because, like you said, it’s very frustrating when you have the seed, you… As I mentioned, one cross, one seed, so you put in a lot of effort, and then they don’t germinate. And as a breeder, you think, “What was all that for?”
And now our osmanthus are big enough, they produce enough open-pollinated fruit that we can do those seed experiments in a larger number. I think that’s gonna be able to provide the kind of results that we need going forward.
Ping Yu: Oh, that’s great because I think if we can really solve that problem and kind of find a solution for the seed germination, that’ll be great.
Because right now, I think for, at least for in the US, most of grower who produce osmanthus, I think the majority of them produce the Osmanthus fragrans. They don’t have even a specific cultivar that’s just most popular among the customer that they serve. But the cutting is the main way for them to propagate those, and I would love to say that our industry adapt more diverse color of this plant because there are so many good ones that needs to be head to the market, that needs to be planted more, so that more people can appreciate, can like them.
Inside Lisa’s Germplasm Collection
Ping Yu: Can you share some of the germplasm that you have collected over the years that you are working for the osmanthus breeding, or, or can you share some of the update of your osmanthus breeding program?
Lisa Alexander: Sure. I mean, I can tell you what we have, and then physically I can share it through things like material transfer agreements and plant evaluation agreements. Like I said, I’ve tried to get quite a large germplasm collection. I think that I have a large and diverse collection. It’s Osmanthus armatus, heterophyllus, fragrans, and fortunei.
I keep about 45 to 50 cultivars. I wish I had more, especially of Osmanthus fragrans. We’ve tested many more. Anything that’s available in this country, we have tested in McMinnville, Tennessee, and some of them we discarded because they weren’t going to make good breeding parents or they weren’t cold tolerant, so we don’t keep, you know, we don’t keep everything here. We do keep quite a large collection.
We propagate it through semi-hardwood cuttings. We’ve gotten pretty good at that. I would not say it is at acceptable industry levels of success, but we, you know, if we get 50%, we’re pretty happy with when we root our osmanthus.
Pre-Breeding and Parentage Markers
Lisa Alexander: We use, like any breeding program that’s academic, we really struggle between, you know, I have to have scholarly output in osmanthus. I need to share basic knowledge. I also need to create plants.
So the way I sort of balance that in my program is I do a lot of pre-breeding activities. Pre-breeding includes things like flow cytometry to make sure that they all have the same genome size. It also includes a lot of crossing and pollen tube work. So I wanna know, are they self-fertile? Do I need to emasculate and bag? Are the crosses gonna be equally compatible? If I put, you know, armatus pollen on a fragrans or vice versa, are they actually gonna take? So we do a lot of that pre-breeding work. We decide what crosses we think are gonna take, and we make a lot of them.
We also have switched to propagating a lot of the plants that we want as parents, collecting open-pollinated seed, and then using molecular markers to reconstruct the parentage. For me, that actually is easier and faster than making all those different crosses, because I can take this batch of open-pollinated seed, extract DNA, run a one multiplexed marker set, and then I group them into different parents. You don’t always have all parental combinations represented that way, but it is a good way to manage that workload.
We try to evaluate in pots at an early age, and it’s really saved the field for more advanced selections. And then of course, teamwork is invaluable any time you wanna make any kind of a genetic improvement. So to have people that are interested in compact plants that say, “I wanna judge the compactness,” or, “I wanna look at the cold more thoroughly,” or, “I wanna look at the fragrance, you know, aromas.” So constructing a good team and then making really targeted crosses are sort of the tenets that underpin our breeding program.
Zigging and Zagging Around the Straight Line
Ping Yu: Yeah, ‘cause I can’t imagine, like, you kinda have to work very strategically to check both the box from the academic output and your cultivar release and then all the plants that you want to create.
Lisa Alexander: That’s right, yeah. So I always tell students, you think in your mind of a straight line between, you know, you make a cross and you evaluate and then you release and it’s a straight line, but you don’t get scholarly output that way. You have to zig and you have to zag around your line.
And, you know, we’ve published on things like evaluating the floral traits in our osmanthus core collection, developing molecular markers that we distribute to use for the community. We also use them in our own program, but now they’re useful to everybody. So, you know, we try to balance, try to make the scholarly output very useful and supportive to the breeding, but it also has to be adjacent to the breeding just because the breeding does take, you know, take a while.
Seven to Ten Years from Cross to Market
Ping Yu: Yeah, and how long does it take for the breeding? Just to give an example, like, there was… Well, I think that you have many of the hybrids already. Just give us an example and showcase how long does it really take from getting the germplasm to the sibling or to the offspring of that parent [laughs] plant.
Lisa Alexander: It takes a long time. So, and you can short… And as your breeding program progresses and you start to fix some of the traits you want in your population, you can reduce some of the time. But in the beginning, I would say it easily takes seven to ten years.
So the crosses that are in my field now that are in the third year of evaluation, those crosses were made in 2018. So you, you know, you make the cross and then you wait, and then the seed germination itself is six months, you know. And then you might evaluate it in the pot for a year and then you put 2-0 seedlings in the ground, evaluate them for at least two seasons, maybe three, and then in USDA, we have quite a stringent testing program over multiple landscapes, multiple hardiness zones. Or if that work was supported in any way, you might… There might be a nursery or some group that takes it and markets it for you. But in… Generally, if the Arboretum releases a cultivar, we’re kind of on our own to do all that testing, and so that part takes a while.
Once you have a trait fixed in your population, for example, once I know that all of the offspring are going to have smooth leaves, for example, there might be a step that can be taken out and be short as you start to fix the traits that you want. But trees, traditional breeding, you’re looking at seven to ten years from a cross to something that is market ready.
Ping Yu: Yeah, I know. That’s why I… while you were talking about like a woody tree or trees and woody plants, I was laughing ’cause I know how long it takes for people to get one cultivar created from the beginning. It is years of hard work before you can actually see the offspring.
A Traditional Breeder with Targeted Tools
Ping Yu: What are the tools or methods you use for your breeding program? Are you… Would you consider yourself as a traditional breeder or a combination? Well, I would think maybe a combination of the traditional breeder and also use some of the advanced tools in your breeding, right?
Lisa Alexander: Yeah. So that’s an interesting question because I think plant breeders, you know, you get pushed towards different… towards the utilization of new and different technologies for your program, and that’s fine. But I would call myself a traditional plant breeder at the end of the day because I think more in terms of, you know, population level cultivar development, population level methods of selection, like recurrent selection and backcross breeding and things like that.
Of course, we have to stay abreast of the times. We have to learn how to use technologies as they come. Part of that, again, is getting a great team of people around yourself, because not one person can do everything. Another is knowing what technologies are going to be useful and what, you know, what maybe isn’t. There are technologies that might be useful to me when I’m breeding a hydrangea that are not going to be useful for a tea olive.
Some of the tools that I use in tea olives are microsatellite markers, and these markers I use for the parental reconstruction because they’re still the best ways to do that. They’re not the newest technology, but as far as reliability and affordability and can you do it in your lab every season when you have a batch of seedlings to screen, the answer is yes.
So even though I’m a, I would say I’m a traditional breeder, most of the tea olive breeding is pollen to pistil, get the seed, grow out the seed and look at it. But I do use tools, like I mentioned, the microscopy and the flow cytometry in pre-breeding to sort of narrow down and target what crosses I wanna make. And then I do the open-pollinated progeny reconstruction. I use molecular markers on the back end to avoid, you know, the one seed, one cross situation. It makes a lot more… It frees up my time to not have to make all those crosses that aren’t even gonna germinate. So it sort of gives a bias towards the ones that are going to germinate, and so you don’t spend all your time on the ones that were never going to germinate.
Also, we’re hoping to add new tools. We’re hoping to add some controlled environment testing, just so for cold hardiness, just so that not all of our screening is, does it die in the field? So that will help save field space for even more advanced and promising selections.
And then as sequencing becomes cheaper, we will eventually use the sequence of both parents and really try the whole genome sequence of both parents to really try to look at how specific genes are passed to the offspring in osmanthus. And that’s when you can really target things like bright orange flower color or, you know, some very specific trait that you might wanna manipulate.
Working Around One Cross, One Seed
Ping Yu: Mm-hmm. Yeah. Can you elaborate a little bit on the tools that will help you do the, like, resolve the problem with the one cross, one seed issue?
Lisa Alexander: Well, I mean, there… Biologically, there’s no way around it. It’s one cross, one seed. But the way that you kind of overcome that, as I mentioned, is one, you really try to make targeted crosses so that you’re not, you know, wasting your time on trying to baby ones along that aren’t good.
Another thing is just, like I mentioned, to go backwards, it feels like, and really understand seed germination. You know, what is the dormancy? What is happening?
One cog in the wheel is that Osmanthus fragrans is adapted. They don’t… They’re evergreen, and at least in the US, they’re semi-evergreen. Osmanthus heterophyllus and armatus are temperate species, so they both have a cold stratification requirement that Osmanthus fragrans does not. So when you’re talking about osmanthus seed germination, you do have to be species-specific. And then when you have a hybrid seed, which is it? Does it need stratification? Does it, does it not? So those are challenges that we’re having to face to over… you know, to overcome that one cross, one seed issue.
For molecular tools, an issue in osmanthus and many trees is that because they’re not inbreeding, it’s hard to develop the kind of experimental populations, like an F2 population, that a geneticist would normally use to associate a certain trait with a gene. And so as we’re able, as sequencing gets cheaper, and as those technologies become more available for niche plants, we’ll be able to sequence the parents of a cross and, you know, sequence their, even their F1s crosses, and really try to pinpoint those specific individuals that have the genetics that we want. And again, that’s just a way to target it, right? To save your manpower and your field space for the very most promising selections.
Ping Yu: Yeah. And I think there’s a lot of things that can be done to improve the breeding for this specific tree or specific plant.
One Amazing Plant Could Turn the Tide
Ping Yu: But how do you think, as a breeder, how can we work together to improve the popularity of tea olive in general for a larger audience? Because there are so many good cultivars and like the Qiannan, they have the pink little leaves. And then the smell of the Osmanthus fragrans is just gorgeous. They just… They’re just so good, and so I would like the general public or more people would love this plant like we do. How… Are there any strategies that you can think of right now to help increase the popularity of this tree?
Lisa Alexander: Well, I think we’re doing it. I… This is… think I… This is it. [laughs] But no, one of the strategies is to make sure that as Extension… as people that deal with producers and nursery growers to make sure that they know it, and to make sure that they have the resources to actually grow and propagate the plant. I mean, that is the number one way, because, yes, we can engage with consumers on the one-on-one level, but the real surge in popularity is when it’s gonna get adopted by the big box store or by, you know, a company, a product catalog that gets to everybody’s hands.
And the way that’s gonna be done is by getting one that can be propagated well, regularly, uniformly. And so part of our breeding program, and Ping, yours, you’ve been working on this as well, is… You know, I might have a good hybrid in my field, but if it’s not easily rooted by cuttings, it’s not gonna move forward.
So one of the absolute cutoffs in my program is you have to be able to propagate the plant. We’re not releasing anything or promoting anything that is difficult to propagate, and when we do release this cultivar or cultivars, it will come with a how-to-grow sheet that we will put in the grower’s hands, say, “Here’s the plant, here’s how to grow it, here’s how to market it.” And so I think that’s gonna be huge.
And with anything, you know, it only takes one amazing plant to turn the tide. Think of Endless Summer hydrangea.
Ping Yu: Yes.
Lisa Alexander: It, you know, if we could make a, you know, an orange sunset, right, osmanthus that can grow through Zone 6, that could turn the tide. And it only takes one plant.
Ping Yu: Yeah, you’re right. Yeah, the moment that you said Endless Summer hydrangea, I’m like, yeah, we need an Endless Summer, or like the orange-red sunshine for osmanthus.
Lisa Alexander: My dream, my vision is a picture in a catalog of someone’s home decorated for Christmas, but in front of the door, on each side of the front door is a pot with an Osmanthus fragrans in full bloom. And imagine the scent if you walked up to somebody’s door and there were two blooming Osmanthus fragrans, glossy, green foliage, perfect for Christmas, except there’s actual blooming flowers. I mean, if that picture made it, you know, into one of the catalogs, that would be a good thing.
Ping Yu: Yeah, that would be a game changer.
Hydrangea and the Other Breeding Programs
Ping Yu: [laughs] Speaking of hydrangea, are there any other breeding programs that you are currently working on?
Lisa Alexander: Yes. Well, I’d say that hydrangea is my most active breeding program. I have some sort of breeding going on for almost every species of hydrangea that we can grow here, as well as interspecific hybrids. I also do a lot of genomic work in hydrangea. There is a little more market support, industry support for advanced breeding technologies for hydrangea, so I do a lot of work in that sphere as well. Oakleaf hydrangea is one of my favorite plants.
Ping Yu: Mm-hmm.
Lisa Alexander: It’s native to… I think, I love that we both like the plants where we live, that they… And I really think that’s true for so many people, that the plants really tie you to a place and, you know, to a period of your life, for a lot of people, their childhood, and that can be very powerful.
But I think oakleaf hydrangeas are great plants, and so I have a big breeding program for those as well. Fringe tree, which is an osmanthus relative, we grow. And then we have some evaluations and breeding for incense cedar, for manzanita, for other woodies. And then I contribute to some of the programs, other programs at the National Arboretum. But hydrangea and tea olives are, I would say, my main two interests right now.
Ping Yu: That’s great. Yeah, the reason why I asked that is because I kinda know that you’re also working on hydrangea, too, but I didn’t know that the hydrangea is another one of your favorite plant and it has tied to your childhood.
Lisa Alexander: [laughs] That’s right.
Genome-Enabled Tools for Woody Crops
Ping Yu: So what is the next exciting thing for you in your research, in your breeding world?
Lisa Alexander: Hmm. So many exciting things. Well, as a breeder, every seed you sow is exciting. Every spring could be the one that is, this is the year where you see the magic plant. So there’s something very exciting about being a plant breeder just in general.
Another thing that excites me is a lot of the work that ARS is doing with Breeding Insights. So Agricultural Research Service has a goal of making or, sort of enabling all the crops we breed to be genome-enabled and have the same kind of technical or technology-based support that, you know, the big crops have. And I think that’s really exciting, you know, because I’ve always worked in non-model, in woody crops. You know, it feels like you don’t… You know, you get the crumb, like the technology crumbs that come down, you know, from other species. ARS is making an effort to really have those technologies transferred into all the crops.
And so I think there is an exciting future for, definitely for hydrangeas, but even for tea olives and for fringe trees to get to use some of those genome-enabled technologies to make improvements in those plants. And so I’m really excited about that.
Ping Yu: Yeah, that’s cool. If any… Right now, any little tiny improvement on any of those plants would make a big difference down the road with the breeding program that you’re running. Yeah, for sure. Can you…
Lisa Alexander: Yeah, and as you know, it’s not even all about my program. You know, you do your part. It’s like a train that’s moving forward. Like you get on and you get off and somebody else gets on, and the people that were behind us that brought in all these plants, that did the effort, you know, they did their part, and we do our part, and hopefully, you know, the people that get on [laughs] after us get to really, you know, have the fruit of this genome-enabled work that we’re sort of laying the groundwork for now.
Ping Yu: Yeah. So carry on the legacy. Or I think there’s one saying about what you just described it. It says the people who plant the tree, and then the next generation will come in and enjoy the shade. Right.
The Arboretum as a Node of Distribution
Ping Yu: Can you elaborate a little bit about your collaboration with National Arboretum? Do you do any work with them or with the plant exchange or anything?
Lisa Alexander: So I work for the National Arboretum.
Ping Yu: Oh, yes.
Lisa Alexander: Yes. The Floral and Nursery Plants Research Unit is located in the National Arboretum. And so we do, I mean, my colleagues do a lot of work, especially Todd Rounsaville. He manages the plant germplasm system for woodies, and so he does a lot of work with plant exploration, collection. He’s very passionate about that and excellent at maintaining those database and those records.
As far as osmanthus goes, we really rely on university colleagues because our ability to exchange plants has been better in the past.
Ping Yu: Yes.
Lisa Alexander: Right now, there’s a lot going on between… at universities where professors there are really leading the vanguard, and also commercial nurseries, saying we want access, you know, to these great plants. And so, you know, I feel like it’s my job to form relationships with those nursery owners and, you know, encourage them and then, you know, try to get those products, like once they’re brought into the country.
So I currently… The Arboretum currently does not have ongoing activities in osmanthus exploration or exchange, but certainly in other species are very active.
Finding Plants in the National Plant Germplasm System
Ping Yu: Yeah. And then I kind of get a piece of how the National Arboretum work in terms of with the big picture for exchanging plant materials in general, is that one… for your program you guys will collect all those species that you can from other resources, and now, and bring them back to the US and then for other people who wanted to research on those, they’re gonna come to you, and then you do the exchange or other format of exchange to make it happen, right?
Lisa Alexander: That’s right. Yeah. So I would say the first resource would be the National Plant Germplasm System. So you would go to the GRIN interface website, and you can see what all osmanthus species, seed especially, are kept within the National Plant Germplasm System, and that would be the first place any researcher should go if they want to look for a plant. That’s, you know, the reason it exists.
Then if, you know, you’re reading a paper and you see, okay, Dr. Alexander has obviously trialed these 30 plants, then you could reach out to me, and we can often do something under a plant evaluation agreement or a material transfer research agreement or any number of vehicles that, that we use to, you know, share plant material with restrictions because we do want this to be shared.
I mean, that… the goal… One of the lovely things about working for the United States Department of Agriculture is we really are here to support the people in the industries of the United States, not to be a, “This is my, you know, research pool and, you know, keep your hands off.” We want to be a node of distribution and not, like, a silo of collection. Absolutely.
Where to Find Lisa’s Work
Ping Yu: Yeah. Yeah. So with that in mind, if people wants to find more information about what you have done with your breeding work, not necessarily for osmanthus, but other species, where do they… Where do you recommend them go and look for more information on that?
Lisa Alexander: Well, you can certainly look at the US National Arboretum website. That lists the scientists there and the projects that they work on and recent publications. You can Google Lisa Alexander Osmanthus, and luckily, many of our journals today are open access, which is, I think, a wonderful way to get more research out into the open. And so a lot of those papers will just come up. And I try to publish timely and let everybody know what I’m doing.
Also, I try to talk to stakeholders, to master gardeners, to scientific groups, and really talk about what we’re doing here and just promote osmanthus in general.
Ping Yu: Yeah, that’s great, ’cause I think we need to get the word out there more so that people would know this wonderful species a little bit more, and hopefully appreciate that more. One of the reasons I do this podcast is to share the plant power to a larger audience so that people would appreciate horticulture in general a little bit more.
Lisa Alexander: Well, you do a great job.
Ping Yu: Thank you. So thank you for taking out of your busy schedule, talking with us on this wonderful plant and all the great work that you have done and is doing down the road. But thank you, Lisa. I really appreciate that.
Lisa Alexander: Thank you, Ping, for having me. I appreciate it. Have a great one.
Ping Yu: Yeah, thank you.
Closing
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Transcript produced for Blooms and Beyond / UGA Center for Urban Agriculture