Wednesday, September 24, 2014

An August Visit to Yew Dell - Pomegranate, Banana, Pineapple Lily and Bamboo in Kentucky!

Late last month, my wife and I were passing through Louisville, Kentucky and took the time for a quick visit to Yew Dell Botanical Gardens.

It's not the biggest garden by a long stretch, but I have to say I was mighty impressed and surprised with some of the plants I saw there. Here are some of the highlights:

Aster divaricatus, White Wood Aster, pristine foliage in August plus a carpet of starry flowers. What could be nicer?

Not blooming yet, but looking incredibly robust and healthy, here's another aster - A. oblongifolius "Raydon's Favorite," which wins rave reviews from Mt. Cuba Center

OK, this is not so pretty, but botanic gardens are useful in part to see the brownouts you'll rarely find in a gardening magazine or nursery catalog. This is Coreopsis verticillata Golden Gain.  

More proof that Firewitch Dianthus can make a beautiful groundcover

The sign said Ensete montevidensis, although I've seen usually seen this listed as Ensete ventricosum, cultivar "Maurelii". The common name is Red Abyssinian Banana. Unfortunately, it's only hardy to zone 9, so I imagine Yew Dell planted it as an annual, where it adds some bold and striking tropical ambiance.

I was excited to see what appears to be a thriving specimen of Eucomis comosa, the Pineapple Lily. What beautiful foliage! And even past its prime, the flowerhead is still attractive. I've often seen Pineapple Lilies labeled as hardy only to zone 7 or even zone 8, so it was a real treat to see it growing well in zone 6. (I suppose it's possible that the gardeners lift the bulb for overwintering...I'll have to make inquiries...)

I was surprised to see some Fargesia rufa "Green Panda" clumping bamboo growing happily in the shade at Yew Dell. Later I realized that Green Panda is supposed to be cold hardy to zone 5, so it should be able to handle Louisville winters without any problems. 

This was my first time seeing Green Panda in person and I have to say I think it looks pretty good in the flesh (so to speak). I'm not sure that I have enough shade at this point to keep it happy during a hot Southern summer, but it's tempting to give it a try anyway...

Splish! We heard some splashing sounds as we passed a tiny pond. Close examination revealed this fella.

Peeking through the greenery, we spotted another frog sheltering in the pond

Tragic, but beautiful.  Not sure what kind of bird this is. Maybe a Pine Warbler?
Some sort of Lantana camara. Such cheerful candy colors! Definitely planning to add some Lantana to my garden in 2015.

Anyone know what this is? It looks like a really nice groundcover. Maybe some type of sedum? There was a sign nearby that said Manfreda virginica, but clearly that's not this plant

Here's your trusty blogger leaping into the photo to selflessly serve as a yardstick in measuring this 10-12 ft tall banana plant. Maybe Musa basjoo? No sign here either. If it is M. basjoo (or another Musa), I'd be very interested to hear how the garden overwinters them (although they do seem to be located in a protected spot at the edge of a stone wall that presumably absorbs some heat in the wintertime and helps create a warm microclimate).

I've seen Nepeta x faassenii "Walker's Low" Catmint recommended by numerous sources, but it wasn't looking so hot at Yew Dell when I visited in last August 

Here's an (unlabeled) Oakleaf Hydrangea looking kind of crispy and stressed in a bright partial shade location

Sorry for the overexposure in this photo, but trust me when I say that this Oakleaf Hydrangea was growing in significantly more shade - high dappled shade, but shade nonetheless - and it looked much happier than the Oakleaf Hydrangea that was forced to cope with more sunshine. Seeing these two plants nearby reinforced my suspicion that Oakleaf Hydrangea probably prefers mostly shady conditions in hot summer climates. (Well they probably can tolerate a fair bit of sun with lots of supplemental water, but if left to their own devices with minimal extra watering, I suspect they only look their best in the Southeast with lots of shade.)

A pomegranate growing cheerfully in zone 6 Louisville?!
Blew. My. Mind.
True, it is a dwarf pomegranate (Punica granatum Pleniflora), but still I did not know that pomegranates could survive north of zone 7. (I've actually been under the impression that even zone 7 was iffy.)
Seeing this pomegranate seemingly growing happily here has forced me to reexamine my assumptions!

The foliage on this hybrid Witch Hazel - Hamamelis x intermedia "Westerstede" - had seen better days.
Sedum reflexum, Stonecrop, looks like it can make a great groundcover. (I don't think I saw a cultivar name listed, but this looks like photos of Blue Spruce that I've seen online.)

Some kind of tall sedum (not sure which -- I thought it was S. spurium Voodoo, but that's clearly wrong). Whatever it was, there were loads of honey bees buzzing about happily all over the copious flowerheads.

Silphium laciniatum, Compass Plant, a U.S. prairie native with beautiful compound leaves and soaring stems (8-10 feet tall?) that - as shown here - can topple to Earth in dramatic splaying fashion

Solidago rugosa "Fireworks", the top-rated goldenrod in a Chicago Botanic Garden trial, simply stunning en masse as shown here. Solidago reportedly provides bees with an important late-summer source of pollen and nectar.
No tag on this, but I suspect it might be Lespedeza thunbergii. It's a pretty shrub / large perennial, but I don't have any plans to add it to my TN garden and I'm a little surprised (if my identification is accurate) that Yew Dell still has it, given that concerns over its invasiveness have landed it in the Significant Threat category of the Kentucky's Exotic Plant Pest Council

Wednesday, September 10, 2014

Pretty Dangerous

The attractive but toxic Stinging Rose (Parasa indetermina) caterpillar enjoying lunch in a crabapple tree
Stinging Rose (Parasa indetermina) caterpillar enjoying lunch in a crabapple tree on a hot August afternoon

Pretty + Dangerous = Stinging Rose Caterpillar (Parasa indetermina).

I found not one but TWO of these beauties on our Sugar Tyme Crabapple a couple of weeks ago. (The other one was smaller and wedged between two leaves, which made it harder to take a good photo of it.)

I had a devil of a time trying to ID the caterpillar, but ultimately found success through Google+ member Garden Experiments, who confirmed some of my own Internet research.

The Featured Creature blog has some great photos and description of this caterpillar.

The University of Arkansas Arthropod Museum describes how the Stinging Rose can deliver a severe venomous punch through its spines to any creature foolish enough to attack it.

The adult moth form of the Stinging Rose may not be as flamboyant as the caterpillar, but I think it has a soft, elegant beauty all its own.

In 2005, the USDA noted that the Stinging Rose has been found in many Eastern and Midwestern states, but that it is "considered uncommon to rare" throughout its range and that "most states in its range contain only a few populations."

So I feel very, very fortunate to have spotted a couple of these in my own backyard!

As with many species, it seems that the Stinging Rose has suffered due to habitat loss caused by human land-use practices. One issue (if I'm reading the USDA report correctly) seems to be that caterpillars will overwinter in the leaf litter below a tree in forest settings. In a landscape situation like the one in my backyard, I don't see how the caterpillar will survive the winter since the tree is planted in the middle of a lawn. Not much leaf litter there.

I suppose that gives me another reason to minimize the lawn and create more landscape beds of trees, shrubs and perennials were the leaf litter can be left to decompose naturally over the winter and into the spring, and where any overwintering moth larvae have a better chance of surviving to emerge as moths, lay their eggs and start this whole miraculous cycle once more.

Monday, September 8, 2014

Fairchild Garden Breeds Better Jackfruit, Hosts a Jubilee!

Large fruit growing off the trunk of a Jackfruit tree.
(Photo courtesy of Fairchild Tropical Botanic Garden)

This coming Saturday (September 13th), Fairchild Tropical Botanic Garden in Coral Gables, Florida will be hosting a Jackfruit Jubilee.

I had a chance to speak with Noris Ledesma, Fairchild's Curator of Tropical Fruit, about the amazing jackfruit (Artocarpus heterophyllus) and the research that Fairchild has been doing on the plant.

Garden of Aaron: Tell me about the Jackfruit. It looks huge from the photos I've seen!

Noris Ledesma: Jackfruits can weigh anywhere from 30-70 lbs -- sometimes even more. And each tree, depending on its age, can bear from 20-60 fruits.

Such a large, heavy fruit can be intimidating. People think, "What will I do with this huge, spiny thing?" When we display jackfruits in the garden, people are always amazed. They want to touch them.

As for the flavor, it combines pineapple, banana and mango. Nobody is disappointed when they take a taste. And of course a single large fruit can feed many people.

Garden of Aaron: So what sort of research has Fairchild been doing with the jackfruit?

Noris Ledesma: We started a program back in the 1980s to introduce selected jackfruit specimens from Australia, Thailand, India and Vietnam. We use traditional plant breeding techniques to select fruits based on different characteristics. Then every two years we have festivals to introduce the "best" fruits.

Of course, not everyone agrees what makes a great jackfruit. Americans typically like their fruit to be crunchy,but other cultures, especially Vietnamese for instance, like very soft textures.

Noris Ledesma opens a Jackfruit
(Photo courtesy of Fairchild Tropical Botanic Garden)

Garden of Aaron: What is the history of the Jackfrut in Florida

Noris Ledesma: As long as a century ago, people were already planting Jackfruit from seeds and raising the trees in their backyards. Nowadays there is an industry in South Florida where growers will produce jackfruits primarily for the Asian community. These fruits will be shipped up to places like New York for weddings. When Indian people get married, they often feel it is important to have jackfruits at the table. It's a part of their culture.

On the other hand, for the average American consumer with a small immediate family, a 70 lb. fruit seems daunting. You'd have to invite the whole neighborhood to each such a fruit! These consumers are more interested in 1-2 lb. fruits, so we have focused some of our efforts on breeding smaller jackfruits that could appeal to a wider market.

Garden of Aaron: So what is this breeding program like?

Noris Ledesma: It's a very traditional breeding program. When we talk about breeding and plant genetics, some people get afraid. They imagine we are in a lab, breaking genes and playing God, but we are doing traditional breeding, just controlling the transfer of pollen from male to female plants. It's very easy to distinguish male and female jackfruit flowers, so you can move pollen from one plant to another using paintbrushes. That way we know the identity of the "mother" and "father" plants. When the female flowers set fruit, we bag it to ensure there is no insect contamination. When the fruit is mature, we harvest the fruit, process the seeds and create a new generation of plants. This type of breeding takes many years to get results, so this year we are excited to finally have the opportunity to distribute a new generation of smaller jackfruits to the public.

We have also selected jackfruit that are low in latex. We don't have time in our culture to clean a complicated fruit. The new jackfruits we have developed are low in latex so you can process the fruit quickly, and of course these fruits have very good flavor.

Garden of Aaron: How is jackfruit traditionally prepared?

Noris Ledesma: People use jackfruit in many different ways. In India, jackfruit actually is often used as a meat substitute! And since the seeds have high protein content, they are sometimes roasted like nuts or mashed to make a sort of multi-grain bread.

One exciting thing at the garden is when families of immigrants come to visit and see a tree like the jackfruit. The plant awakens memories and the parents or grandparents can start telling their families about how they used the fruit back in India or Vietnam or Thailand. They don't have to travel thousands of miles to encounter such a tree -- they can grow it in their own backyard here in South Florida.

(Editor's note - Fairchild has a webpage showing how to open and prepare jackfruit.)

Garden of Aaron: Would you say the jackfruit makes a nice ornamental plant in tropical areas?

Noris Ledesma: It can be a beautiful tree. The fruit is certainly eye-catching. And during long, hot summers, the tree's leaves stay shiny and beautiful. If people come to the Jubilee, we will have classes on propagating, fertilizing, pruning and training the tree. It's not difficult to grow in South Florida, but it probably will not grow in other parts of the United States, except in Hawaii.

Garden of Aaron: What about water needs?

Noris Ledesma: It does need some irrigation for its first year or two. After that, it can survive on regular rainfall. Of course, humidity in South Florida is quite high. In terms of nutrition, we do recommend mulching. Our soils in South Florida can be very rocky, so mulch can help the tree's development. And an application of nitrogen fertilizer can help give the tree the energy it needs to produce such large fruit.

Garden of Aaron: Do you think that more people will try jackfruit in the future thanks to the breeding program at Fairchild?

Noris Ledesma: It is our hope that these smaller fruits will show up throughout American supermarkets. Of course, there will still be some cultural issues to overcome. For instance, since a ripe jackfruit still has a green color on the outside, some people who are unfamiliar with it may not be able to tell whether it's ripe or they may think it looks like a vegetable. Probably, it will first win acceptance with second or third generation Asian-Americans who want to try eating jackfruit, but don't want to buy an enormous fruit.

Fairchild's website has a list of Curator's Choice Jackfruit being sold at the festival, including some of the new hybrids with smaller, lower latex fruit.

Thursday, September 4, 2014

A Species Is a Species Is a Species (Except When It's a Cultivar)

Dr. Douglas Tallamy
Professor & Chair of Entomology and Wildlife Ecology at the University of Delaware
I recently had the privilege of speaking with one of my horticultural heroes - University of Delaware professor Dr. Douglas Tallamy - to discuss his ongoing research on cultivars conducted in partnership with the renowned Mt. Cuba Center.

In addition to his scientific research, Tallamy is a darn-good writer and author of the wonderful book Bringing Nature Home, which opened my eyes to the importance of biodiversity in our own backyards and showed us all of us can make a difference by supporting vibrant ecosystems in our gardens.

Tallamy is working with Mt. Cuba Center to research cultivars of native plants. What is a cultivar? I'll answer that question by quoting extensively from Mt. Cuba's Executive Director, Jeff Downing:

The newfound popularity of native plants seems like very good news for the environment. But it’s complicated. The thing is, the vast majority of native plants available in the trade are cultivars. A cultivar is a plant that has been selected for a particular attribute or combination of attributes that can be maintained through propagation. Cultivars are often selected (or created through hybridization) for characteristics like flower color, hardiness, disease and/or drought resistance, interesting foliage, or any other noteworthy feature. In order to perpetuate a distinguishing characteristic, most cultivars are propagated clonally. As a result, for many cultivars, every plant is genetically identical.

Sometimes funny things happen when plants are selected for particular attributes. When roses were bred for disease resistance and floral beauty, they lost their scent (which prompts the question: Would a rose, by any other name, smell like anything?). When the Red Delicious apple was selected for its attractive shape and color, we sacrificed flavor.

And that is where it gets interesting. Are native plant cultivars that have been selected for particular attributes as attractive to insects and pollinators as the naturally occurring species? As gardeners we hope so, since these ecological benefits are a big part of what we hope to gain by choosing native plants. But the reality is that we don’t know, because the ecological value of native plant cultivars hasn’t been widely studied. Until now.

Mt. Cuba Center has funded two graduate student fellowships to research the ecological value of native plant cultivars and Doug Tallamy is participating in part of that research. Along with Mt. Cuba Center Fellow Emily Baisden, he's looking at whether cultivars of native woody plants attract as many leaf-eating insects as naturally occurring species.

(But wait, I hear you cry, why on Earth would I want to attract leaf-eating insects? Well, I'll give you two reasons - some of those leaf-eating insects will turn into beautiful butterflies and moths. And some of them will provide food for birds.)

Here's a snapshot of my conversation with Dr. Tallamy:

Garden of Aaron (GOA): Can you tell me a little about your motivation for conducting this research?

Tallamy: Lots of people tell me that they would like to increase the percentage of native plants in their yard, but all they can find at nurseries are cultivars. So people ask me, "Are they as good as the species?"

The answer is that no one has compared straight species to cultivars in terms of their impact on pollinators or on caterpillars eating their leaves. If you are putting plants in your yard to encourage complex food webs, to support insects who will feed the birds, you want to know whether these plants will be as good in those ways. That's the motivation for the Mt. Cuba project. I've made some predictions for 5-7 years now about the impact of cultivars, but it will be nice to have some data to see what's really happening.

GOA: What are the parameters of your research?

Tallamy: It's impossible to test every cultivar, so we're looking at the typical types of genetic changes that create cultivars. Some cultivars take a green leaf and make it purple or variegated. Others take a fat plant and make it skinny or a tall plant and make it short.

Then there are lots of selections involving changes to the flowers, mostly changing the shape, the petal size, the colors and so forth. What will that do to pollinators?

Finally you have cultivars that are focused on disease resistance. If you important resistance into a a plant, does that also impact the insects that pollinate or feed on it?

GOA: Which plants are you investigating?

Tallamy: We are looking at five different cultivars of Cornus sericea [Red Osier Dogwood]. We are looking at flowering dogwood, blueberries, red cedar, red maple, sweetgum, stag-horn sumac, arrowwood, winterberry and a disease-resistant Princeton Elm.

GOA: How is the study structured?

Tallamy: All comparisons are within a species - that is, we are comparing the straight species to the cultivars. They're all growing at a common garden in Mt. Cuba Center with five plants of the parent species growing in a circle. Then we plant the cultivars in clumps around that circle. If an herbivore can find one plant, it should be able to find the others too. Essentially they're located in the same space and planted on the same day.

GOA: How did you choose which plants to include in the study?

Tallamy: We picked plants that we know have insects associated with them. So for instance, Itea [e.g., Itea virginica, Virginia sweetspire] does not have any caterpillar association. Elm trees are high in caterpillar associations. We are looking specifically for caterpillars and vacuuming for anything else. Actually, we're finding more insects than we had thought we would. We've conducted a couple of samplings so far, but it's still early in the study.

GOA: Do you care to make any predictions as to what the study will uncover? Do you have any hypotheses at this point?

Tallamy: If you make a green leaf purple, you're adding anthocyanins. These could affect feeding behavior.

Variegated leaves take away chlorophyll, so my prediction would be that those plants would support fewer lepidoptera [i.e., moths and butterflies].

In terms of changing a plant's habit - making it shorter or taller - unless that genetic change also alters leaf chemistry, I don't see why it should be a factor for herbivores, so I would predict no change in terms of the caterpillars it would attract.

Disease resistance could certainly affect herbivores. When a plant manufactures a chemical to protect itself from disease, there could be some crossover into deterring herbivores.

It's easy to predict how changing the shape or color of a flower might impact pollinators. Flower energy budgets are tight. When you make petals bigger, you're probably reducing nectar. Double flowers remove the flower's reproductive organs and turn them into petals [i.e., if the flower is sterile and does not produce pollen, there is no reason for pollinators to visit].

In terms of changing colors, I don't know how that will affect the UV spectrum [that many species of insects can visualize]. It could have an impact on pollinators.

GOA: Would it be possible for the horticultural industry to produce cultivars that might attract more pollinators than a straight species?

Tallamy: Sure, you could select for traits that enhance pollination or produce greater nectar load. It might not make the plant prettier, but you could advertise it by saying it would help gardeners to attract more butterflies. I'd say that it's almost certain it would sell for that reason alone.

GOA: What do you hope will be the impact of this research?

Tallamy: I hope that people to will start to think about selecting plants based on their function, not just on their aesthetics. If we can accomplish that goal, I'd be happy.

I'd also love to see traits moved along in ways that don't involve cloning. It would be good if we could have some kind of breeding program that would cross plants and still maintain desirable traits while preserving genetic variability. Red maples are naturally swamp plants that hate dry city climates, but if you're looking for a red maple that will do well under city conditions, you can go to the mountains of Pennsylvania and find selections that have already been made for you. There you'll find red maples growing that have been bred through natural selection to survive heat, drought, wind, cold and very little water. You could collect a number of those, interbreed them and produce plants that have the same survival traits without relying on cloning.

We need to do that kind of native plant exploration for harsh city conditions. It makes no sense at all to say that only plants from China will grow in urban conditions. You can look around city lots and see lots of native plants growing. Washington DC, for instance, is filled with oaks and elms, so it's just an urban legend that native North American plants won't grow in our cities.

GOA: To get back to a statement you made at the start of our interview, why is it so hard to find straight species plants instead of cultivars in the nursery trade?

Tallamy: It's a question of supply and demand. If nurseries thought they could sell the straight species, they would do it. But they have spent a century with the mindset that consumers will only buy plants with fancy names and that you have to introduce new plants every single year like the fashion industry.

Now there's growing consumer demand for natives that will do something in our yards instead of just looking nice. Of course, to find a plant that does both - that looks nice and supports the food web - would be the best option.

GOA: Thank you for your time, Dr. Tallamy. Good luck with your research!

Editorial note -- Dr. Tallamy has compiled a spreadsheet called "Host Plants" showing which tree genera host the most Lepidoptera species. According to the spreadsheet, Quercus (oaks) top the list, attracting more than 500 species of lepidoptera, most of them native. Presumably the spreadsheet is targeted for North American audiences when it characterizes genera and lepidoptera species as native or exotic.