Sunday, February 23, 2020

Nature’s Best Hope (The Book)

So many people want to find the solution for the declines of critters around us: native bees, monarchs and other butterflies, birds. It turns out, just like Dorothy, we had the power to fix it all along:  “The Scarecrow exclaims, “Why didn’t you tell her before?!” Glinda responds, “She wouldn’t have believed me. She had to learn it for herself.” I'm encouraged to see that people are learning—through numerous blogs and social media—that our own yards can make a difference, and the message is getting louder.

Doug Tallamy’s new book  “Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard” makes it clear that every yard—no matter how big or how small—is important to making the difference to the critters that need us. Getting regionally appropriate native plants into our yards, shrinking the non-productive turf-grass spaces (so we can add more native plants!), avoiding pesticides, convincing other people, removing invasive plants … small steps that add up to really big impacts for the ecosystem around us.

After the success of his book “Bringing Nature Home” in 2007, Tallamy has been speaking to groups around the country about why native plants are important from a scientific point view, most specifically because of insect herbivores or, as he likes to call them, ‘the little things that run the world.’ He has reached many a gardener, bird lover, and butterfly enthusiast with his message that native plant-native insect relationships are rooted in years of evolution that non-native plants can’t replace.

I loved reading this book – his sense of humor absolutely comes through. I can see how comfortable he is talking about the subject now. Yet, his sense of frustration is also there. The expanse of lawn is vast in America, and the pull to conform with neighbors by using the same non-native plants is strong. And the rate at which humans are converting wild spaces into unproductive plantings is rapid—we’re losing our chance to make a difference unless we change the mindset that nature lives somewhere else:

Although we must continue to protect good habitat where it still exists, we can no longer afford to ignore the ecological value of the land outside of our preserves—that is, the areas between isolated habitat fragments. (p. 61)

If you’ve not read his first book, I would say this one will suffice as he reviews many of his original concepts. While his first book leaned heavily on research pulled together from others, this book makes reference of new studies since then, including many executed by Tallamy and his graduate students. These studies specifically targeted some of the questions posed about non-native plant interactions with native insects.  In the “Are Alien Plants Bad” chapter, he summarizes a study that demonstrated how ‘introduced plants reduce both species and interaction diversity’ by measuring insect biomass in sites filled with invasive plants vs. primarily native sites.

By every measure, the caterpillar community, and by extensions, the community of insectivores that relied on caterpillars for food, were seriously diminished when introduced plants replaced native plants. […] there were 68 percent fewer caterpillar species,  91 percent fewer caterpillars, and 96 percent less caterpillar biomass than what we recorded in native hedgerows (Richard et al. 2018) (p. 111)

Boneset moth, a specialist
Someone who helps with extra insects

With so many fewer insects, how do we expect birds to keep reproducing? Another study helped answer that. The consequence of these differences was that chickadee populations achieved replacement rate—that is, produced enough chicks each year to replace the adults lost to old age and predation—only in yards with less than 30 percent introduced plants. (p. 113)

A visual way to consider your plant portions in the Georgia Piedmont

In addition to some very valuable information that we can use when educating others, Tallamy gives us some useful terms to make our points. One of the best ones is “keystone plants,” a group of ‘hyperproductive’ plants that help sustain “70-75 percent of local Lepidoptera species.” His first book already identified that plants like oaks (Quercus) and several other top woody and perennial plants supported large numbers of butterflies and moths. Studies have continued to demonstrate that the plants we choose make a difference and that “to be richly productive, plant communities must contain at least some keystone plants.” (p. 142) I honestly always thought his next book was going to be called “Let It Be an Oak.”

Saving large oak trees in urban areas is important

Perhaps one of the best features of the book would be the many ways he helps to answer what he calls the ‘Suburban Challenge,’ especially in his appropriately named chapter: “Will it Work?” He’s had 12 years of watching (and listening to) people try to make changes in areas that want order and conformity. This plus 10 concrete steps in Chapter Eleven followed by 15 pages of frequently asked questions are the types of information and encouragement that people need to move forward with his message.

In the end, nature’s best hope is me, and you, and millions of other humans on this planet with the capability of planting or influencing the planting of native and appropriate plants.

Black swallowtail, raised on native Apiaceae plants

Sunday, February 16, 2020

Snow Today, Gone Tomorrow

This past weekend brought one of North Georgia’s brief annual snow events, but this one seemed even more brief than usual. Flurries started by 9 am in the northern suburbs (I was visiting a friend in Cumming, GA at the time). We popped outside for a few pictures with the grandbaby, not expecting the snow to last very long. Well, by 10:30, it was a mini-blizzard of fat flakes and we decided to leave while we could, heading from Cumming over to Johns Creek.

Red maple blooms (Acer rubrum)

What is that stuff?

By 2 pm, the snow was done, leaving a nice blanket of 3-4 inches in my area with up to 6 inches in the mountains. Already the roads were pretty clear, thanks to warm ground, snow plows, and numerous people driving around. I left Johns Creek to go home, stopping here and there for a few photos of large oaks and maple flowers mixed with snow (those small branches were melting fast as the air temperature continued to warm into the low 40’s).

Oak and old barn in Canton

We had above-freezing temps overnight and the snow could hardly be found by lunchtime as the sun shone brightly in the sky. Another visit to grandbaby found him wondering where it all went. Only the partial shapes of tightly packed snowmen remained.

Oak in Milton cemetery

I checked on a thriving clump of trout lilies (Erythronium umbilicatum) in my yard. They had been blooming just 3 days earlier so I wondered how they fared in such an event. Just one day post-snow and they were blooming in the bright sun!

Trout lilies after the snow (Erythronium umbilicatum)

It’s been a mild winter so far and this didn’t change my impression of it much. This picture posted on Facebook by WSB-TV from a resident in Hall County (note that photo is in the same location each day) pretty much summed up the crazy 3-day weather. We had had torrential rains several days earlier (Thursday), followed by a mild day on Friday, and then snow on Saturday. That’s North Georgia!

Sunday, February 9, 2020

Cultivated Varieties of Native Plants

Monarda fistulosa 'Claire Grace'
As more and more people learn about native plants and their value in the home landscape, the concept of cultivars arises. My blogs have included mention of cultivars over the years as I recognize their value and availability in not just stores but also at native plant sales. I thought I’d write about some of the concerns with using them and mention some of the research that I’ve found.

Let’s set the definition of the term: “cultivar” means “cultivated variety.” In the plant world, it is a plant that someone created or found, recognized it as different (e.g., different flower or leaf color), and trademarked a name for it. Many people refer to native cultivars as “nativars” but—from a grammar point of view—that term is unnecessary. The word cultivar already reflects the concept perfectly so that is the word that I choose to use here.

Let me clarify that this post is not about hybrids. Hybrids are crosses of two different species (e.g., a cross of Lobelia cardinalis and Lobelia siphilitica). Hybrids are usually registered by the breeder and named in way to indicate the cross. Yes, desirable hybrids are sold as cultivars, but not all cultivars are hybrids.

Besides hybrids, cultivars can be a plant sport—also called a selection—found  in the wild or in a garden, that is recognized for a desired trait and then named and propagated to maintain that trait (usually by cuttings or tissue culture). It can also have been bred specially using different plants of the same species as parents. This latter definition is the type that I want to talk about and I’ll call this a “species cultivar.”

You can generally tell the difference between a hybrid and a species cultivar by the name (if it is properly shown): Lobelia ‘Ruby Slippers’ is a hybrid—note that no species name is given, only the genus (it might also be shown as Lobelia x ‘Ruby Slippers’); Asclepias tuberosa ‘Hello Yellow’ is a cultivar of a single species of milkweed. This milkweed cultivar fits my definition of “species cultivar.” 

Are your eyes glazed over yet? Well, keep going because, next, it’s important to understand how cultivars come to be selected. Those reasons affect how we consider them for our use. There are several reasons for selecting a plant to be a cultivar, including:

  • Flower traits (double flowers, odd flower colors, fragrance, longer bloom time/repeat bloom)
  • Leaf color (variegation, dark foliage, leaf markings)
  • Leaf shape (deeply lobed, attractive edges)
  • Plant form (weeping, dwarf, strong branching, spreading form)
  • Fruit characteristics (larger berries, more nuts, fewer seeds)

Phlox paniculata 'Jeana' with one
flower of the species to compare size
'Jeana' is quite popular with butterflies;
 I have written about it here in my garden

As the number of advocates for using native plants increases (and yay for that!), the voices of people insisting that no cultivars be used has grown louder. While I recognize that using straight species (e.g., Asclepias tuberosa) has important value—and is essential for restoration—the discussion about using cultivars needs a broader understanding of the actual cultivar being considered. Some cultivars can be safely used to bring beauty and value to the landscape while still supporting bugs, butterflies, and birds just as well as straight species plants.  The factors that I would consider based on the known research so far:

  • What is the cultivar’s change over the straight species? For example, does it have less pollen and nectar or dark-colored leaves? Or does it have a longer flowering period or a weeping form?
  • How many of the cultivar will be used in the landscape compared to straight species? Using a mix of cultivar and straight species is preferable to using only the cultivar (to improve genetic diversity).
  • Why is the cultivar being considered for use in this planting? Is it a showy landscape where natives would not be used if this cultivar couldn’t be used to add some star power? Would they use an exotic plant instead?
  • Is this for a restoration project? Cultivars and even out of region straight species plants should not be used for restoration.

Recent research by Doug Tallamy and others focused on the question of how supportive cultivars are to native insects. Here is some of the information that I found.

From A Way to Garden’s podcast interview with Doug Tallamy in May 2018: “We just finished a study looking at six common cultivar traits in native plants, and seeing how they might have impacted insect use of that plant. Now these are all woody plants, so we did not look at flowering; we did not look at flowers at all. So we didn’t look at the impact on pollinators; other people are doing that. But just in terms of how well leaves support caterpillars and other things that drive food webs. We looked at what happens when you make a green leaf, red or purple. What happens when you change that leaf into a variegated form? What happens when you take a tall plant and make it short, or change the habit in some way? When you enhance fall color? When you increase fruit size? What was the other trait? I think that’s it; there were six traits. The only thing that consistently deterred insect feeding was taking a green leaf and making it red or purple.”

From Ecobeneficial’s podcast in October 2015: “Enhanced berry size is another feature Tallamy examined. With the “bigger is better” attitude now so prevalent, many cultivars are being selected for their enormous berries. Much to his surprise, the larger-berried Highbush Blueberry cultivars supported more insect species than their straight species counterparts.”

Research on how pollinators use the flowers is important too. From Annie White’s pollinator research on cultivars from 2013-2016:
“Some native cultivars attract just as many insect pollinators as the native species. This was seen mostly for open-pollinated seed cultivars such as Asclepias tuberosa ‘Hello Yellow’ and Monarda fistulosa ‘Claire Grace.’ One native cultivar selection, Veronicastrum virginicum ‘Lavendelturm’ actually attracted significantly more total pollinators than the native species and had a longer bloom time. This illustrates that there’s potential for pollinator-friendly cultivars (with long bloom periods and high nectar production) to be selected for and marketed.
One clear trend was observed across all species; the more manipulated the cultivars became, the less attractive they became to pollinators. Cultivars such as Achillea millefolium ‘Strawberry Seduction’ and Symphyotrichum novae-angliae ‘Alma Poetschke’, which are the result of repeated selections in breeding programs, attracted significantly fewer pollinators in nearly all pollinator groups.
If evaluating native cultivars for use in a pollinator habitat garden, try to limit the use of cultivars to open-pollinated seed-grown “selections” or “sports” of the native species. Cultivars that differ significantly in color and morphology from the native species should be used cautiously and cultivars with hybrid origins should be avoided in the context of pollinator habitat restoration.”

From The Humane Gardener, I found an interesting interview with the same Annie White; the interview gives an expanded explanation on her point about hybrids, using the Lobelia cardinalis x Lobelia siphilitica hybrids as an example. Read more here.  

So if the question asked is: Should we choose cultivars of native plants? The answer is “It depends.”

The considerations, again, that you should consider: 

1) If the plant has flower traits that reduce nectar and pollen, then NO; 
2) If the plant has dark leaf forms, then NO; 
3) If the plant has other modified traits such as form and fruit size, then probably OK; 
4) If the plant species are NOT regionally appropriate for your garden, then NO; 
5) If you will be planting some of the straight species as well for biodiversity, then probably OK. 

The bottom line is that we should know what we’re buying. If you want to buy a cultivar, it’s important to do the research to understand how well the plant will support local native partners like bees, butterflies, and birds (or accept that is not why you’re buying it). If one is not willing to do the research, then the best recommendation is to buy straight species.  

Clethra alnifolia 'Hummingbird'
cultivated for dwarf form
Clethra alnifolia 'Hummingbird'
always has summer pollinators

Sunday, February 2, 2020

Native Evergreens in the Southeast

Patridgeberry (Mitchella repens)
In the quiet of winter, green plants in the southeast are a welcome sight. They are a beacon of life in what can be a very brown time. And of course they are good shelter for birds and help to provide a bit of privacy.

Last week I talked about invasive evergreen plants. We are fortunate to have a good selection of native evergreen plants to use in the landscape, from perennials to shrubs to vines and, of course, trees. 

Here are a few of the ones you might consider if you are looking to add some winter green to your landscape.

Perennials: Green and Gold (Chrysogonum virginianum) is a lovely yellow-flowering ground cover; partridgeberry (Mitchella repens) offers bright red berries in winter; the leaves of beetlewand (Galax urceolata) bronze to a rich mix of green and burgundy; ground orchids like Tipularia discolor and Goodyera pubescens delight you with the thought that you are growing orchids outside; evergreen gingers (Hexastylis spp.) bravely hold green leaves above the leaf litter; Christmas (Polystichum acrostichoides) and ebony spleenwort (Asplenium platyneuron) ferns are so hardy; and patches of moss glisten when revealed among the fallen leaves.

Chrysogonum virginianum in April on a
roadside embankment in North Georgia
Hexastylis arifolia in December at Hard
Labor Creek State Park 

Shrubs: Florida anise (Illicium floridanum) likes shade and moist conditions; Florida leucothoe (Agarista populifolia) is my go-to deer-resistant shrub for part-sun; dwarf wax myrtle (Morella cerifera var. pumila) is great for full sun; dwarf yaupon holly (Ilex vomitoria) is a bit of a meatball but looks better if you avoid the pruners; creeping pieris (Pieris phillyreifolia) is surprisingly garden worthy considering where it grows naturally (swamps); inkberry (Ilex glabra) is so handsome; mountain laurel (Kalmia latifolia) cultivars give us so many choices; and Rhododendron is perfect for that eastern side of the house.

Many of these plants have their natural range in the Coastal Plain, so do consider what might be most appropriate for where you are and your landscape goals.

Agarista populifolia in January
Kalmia latifolia in December

Trees: Thank goodness for so many native pine trees (Pinus spp.)–they keep the green front and center; eastern and southern redcedar (Juniperus virginiana)–which is not a cedar at all; the festive American holly (Ilex opaca) which has red berries and green leaves (well the female does); Carolina cherry laurel (Prunus caroliniana) has glossy leaves; southern magnolia (Magnolia grandiflora) is very regal; wax myrtle (Morella cerifera) in tree form provides fragrant small berries (female, again); and our native hemlocks (Tsuga spp.) gracefully anchor our shade gardens.

So if you love a bit of green come winter, select some of these great native plants to be a part of your landscape.

Southern redcedar
(Juniperus virginiana var silicicola)
Canadian hemlock (Tsuga canadensis)