Keystone Plants Maximize Small Spaces

Yards are getting smaller and the conversion of natural habitat to residential communities is shrinking the availability of native plants to support native insects. While we should protect native habitat as our first choice for supporting native insects, we have learned that we can make a difference in our designed landscapes by choosing the most productive plants. 

“Keystone” is the term for the most productive plants in terms of how much they support insect herbivores such as caterpillars, the larval form of butterflies, moths, and sawflies. The more insects a plant can support, the more productive it can be for the local ecosystem that depends on those insects (like birds).

Native Clematis

It’s too hot and dry to plant now, but you might be thinking of what you’ll buy and plant in the fall so now is a good time to make a list. Including some keystone plants would help you take your efforts further than without them. 

I had a hard time finding a good list so I created one using Doug Tallamy’s early resources. You can download and print my list from here. Of course you’ll want to first take stock of what you might already have – for example you might already have an oak tree or a maple (or if your neighbor has those, you can usually consider them close enough to count). If so, plant for maximum diversity by choosing something new like a river birch, a willow, or a hawthorn.

If you have very little space, you might consider choosing keystone herbaceous plants (these are your perennials, see the back side of my handout for them). Homegrown National Park has some nice resources for using keystone plants in containers; here is a link to the Southeastern one. You’ll notice them using the keystone plants goldenrod, asters, and sunflowers – those are the top 3 keystone perennials. I've included links to earlier blogs about those 3 plants so you can see some of the choices available.

So walk around and see what you've got and make plans for adding new ones in the fall to amp up the biodiversity in your garden and in the ecosystem.

July 2024 Moment in Nature

It has been so very dry here the last month or so and quite hot as well. I have been watering my pots and some of the actively blooming in-ground perennials to help the insects that need those flowers.

One night it finally rained a lot and I walked outside to see how the plants were recovering. As I walked through the front, I spied this small frog (identified by a friend as a Spring Peeper) enjoying a moist leaf on the wingstem (Verbesina alternifolia). It seemed like a good sign and a much needed refresh for this month's #momentinnature.

Spring peeper

I found another couple of them later in the week in the backyard, so here's another photo showing the distinctive marking on the back (kind of an X).

Spring peeper

Do Native Pollinators Prefer Exotic Plants?

Certainly this is not a new question but a recent comment by someone about pollinators seeming to like - even prefer - the flowers of naturalized exotic plants made me go looking for information, specifically about native pollinators.

Tiger swallowtail on Tithonia

I do think that we have to establish first that native insects are dealing with an altered landscape; non-native flowers have only been here about 400-500 years, a blip in evolutionary time as far as insects are concerned. Second, as a result of some naturalized plants (like Queen Anne’s lace, an exotic species that is related to a native but less common species called wild carrot), the abundance of exotic weeds may have now almost replaced whichever native plants would have been present, leaving native insects little choice but to use exotics. Third, we should recognize that pollinator preferences for certain flower types (short vs. long floral tubes, for example), will affect what plants they can use and if they can adapt.

We know from publications like this one from The Xerces Society that eco-regionally appropriate native plants give us the best diversity of native pollinators. That is, a diversity of native plants brings us a bigger mix of native bees, butterflies, flies, beetles, wasps - including specialists. We should use native plants from our same ecoregion (e.g., Piedmont, Coastal Plain, etc.) to ensure we support pollinators of the same area. 

Specialist bee: Southeastern blueberry bee

What can we expect when native pollinators live in areas of more exotic than native plants vs. when they have appropriate native plants in more abundance: do they prefer the newer plants (exotic) or do they prefer the indigenous plants?

Research published in 2020 by folks in the Department of Entomology at Cornell University found that native pollinators do prefer native plants when available: “Honey bees visited introduced and native plants at similar rates regardless of floral abundance. In contrast, as floral abundance increased, wild pollinator visitation rate decreased more strongly for introduced plants than native plants.” That is, when native pollinators have access to more native flowering plants, they prefer the native ones.  

Another study published in 2020 based on research in 2016 and 2017 in Maryland, found similar results. The authors feel that exotic plants in pollinator mixes may help pollinators in early spring for generalist insects, but "non-native plants also alter the composition of plant communities, may not support as many specialist bees, and appear to affect individual and network specialization of bee communities with unknown consequences for plants and bees." More study is needed, they conclude.  

Certainly pollinators are using what plants are available and, increasingly, those plants are exotic ones. But don't be fooled that this helps native pollinators overall. Some pollinators - the specialists - may be quietly disappearing if the native plants they need are no longer available.

While exotic and naturalized flowers may provide floral benefits to some native pollinators, the better human strategy is to continue to add regionally appropriate native plants back to degraded and residential areas to support native pollinators, particularly specialist ones.

Mountain mint is powerhouse native for pollinators

Flower Rest Area

 

On our way back into Georgia on I-85, we stopped at the Georgia welcome center near West Point, GA. As we drove in, a bright sign highlighted an area with visible wildflowers so I walked over to see it.  According to the sign and this webpage, it was a collaboration in 2016 to produce a pollinator garden to showcase how we could “reimagine our highways in a way that’s more sustainable and healthier for all species.”

There is a good diversity of plants there. Ropes help define the area and the lawn-facing sides are kept in check with mowers, allowing visitors to walk right up to see the pollinators enjoying the mountain mint (Pycnanthemum), wild bergamot (Monarda), and tall goldenrod (Solidago altissimum). Without the maintenance on those edges, those spreading plants would go all the way to the parking lot.

Mountain mint (Pycnanthemum)

Gulf fritillary on butterflyweed (Asclepias tuberosa)

It was nice to see the succession of blooms and I look forward to stopping by during the year to see it again and again (with a new granddaughter in the Florida panhandle, we will be making more trips this way). The black-eyed Susans (Rudbeckia hirta) were almost finished and the butterflyweed (Asclepias tuberosa) was going to seed, but the downy sunflower (Helianthus mollis) was just starting. Also noted was fading Coreopsis, the occasional purple coneflower (Echinacea purpurea), and grasses. The sign at the front also indicates there might be rattlesnake master (Eryngium yuccifolium) and New England aster (Symphyotrichum novae-angliae).

Rudbeckia hirta ready to feed the birds!

I am not sure if there are more of these areas at rest stops but it is a nice way to showcase Georgia flora and fauna (i.e., insects). I felt much more refreshed after taking a few minutes to watch the butterflies, bees, and beetles enjoying the flowers. I’m sure that birds are using the area as well.

Flowers vs Foliage

 

Deer ignoring American germander

The deer have been brutal to my flowers this year in the front yard. I have a few things blooming – a big St. John’s wort (Hypericum densiflorum), threadleaf mountain mint (Pycnanthemum tenuifolium), American germander (Teucrium canadense), and the white wild indigo (Baptisia alba) are things in the front yard (the back area is fenced and blooms are safe there). Everything else in the front is clipped down to about 12 inches … but perhaps some of it will bloom when they get bored of it.

L-R: American lady, Spicebush swallowtail, Pipevine swallowtail

Yet in the midst of this, the butterflies have managed to find some host plants and lay eggs. I have seen caterpillars on my spicebush (Lindera benzoin), my pussytoes (Antennaria plantaginifolia), my pipevine (Aristolochia tomentosa), and my false indigo bush (Amorpha fruticosa). I have a number of other host plants waiting for the adults to show up.

Normally I apply deer spray (Liquid Fence is my chosen brand) but the weather has been rainy or I’ve been out of town. I will step up my efforts again. In the meantime, I am grateful that my garden provides host plant services even when flowers are few.

June 2024 Moment in Nature

Does it smell in here? This week brought some unusual visitors up close and personal. I heard a thud hit the front porch and found this black vulture casually walking about the front lawn.

After a few minutes, I realized that another one was exploring the shaded area next to the house. Both walked around for a while, then flew up to the roof and from there to the tall pine trees behind the house. By the time I walked out to the driveway, they decided there were no tasty treats here and flew away.

It was fun to see another member of the ecosystem up close. I am always very thankful for the service that vultures perform. #momentinnature

Daisy Fleabane - Spring Roadside Staple

Ubiquitous and seemingly long-blooming, the daisy fleabane (Erigeron) species on our roadsides has been a delight to me - and our pollinators - this year. To the casual observer, these month-over-month blooms might appear to be all the same species.

Most of the common species in Georgia are described as species favorable to disturbed areas, so finding a home on roadsides is perfect. This week we have been in Florida with a new grandbaby, and the drive through Georgia, Alabama, and Florida gave me an opportunity to see just how abundant Erigeron can be on the roads; it was mixed with a variety of other flowers like Coreopsis, and naturalized exotic species like verbena and Queen Anne’s lace. The long, airy stems with clusters of tiny white flowers resemble baby’s breath.

Erigeron strigosus perhaps

I examined some of the plants near my daughter’s house and I think they might be Erigeron strigosus, called rough or prairie fleabane. The leaves are smaller and more narrow, so the overall look of the foliage is sparse. It can be an annual or biennial.

The other species that we all might have seen include Erigeron philadelphicus (Philadelphia fleabane), one of the early blooming ones. This short-lived perennial species has leaf bases that conspicuously and strongly clasp the stem. Erigeron annuus, the annual fleabane has more and larger leaves than other species. Unlike Philadelphia fleabane, its leaves do not clasp the stem at the base. The number of ray flowers also varies among the species but they are so tiny and numerous that I think it would be hard to count them.

In resourcing these species, I found a good website that describes these species and provides comparisons among the 3. Start here with Erigeron strigosus and navigate from there.

I’m glad I got to take a closer look at these lovely native flowers. Meanwhile, new grandbaby is small but I look forward to seeing these tiny hands clutching a bouquet of daisy fleabane in a year or two.