Native Plants Make Every Day Earth Day

We get so much joy out of watching people take pictures of our gardens as they walk by our apartment.

Spring is here in the Northern Hemisphere which means gardening season is well underway. Having spent all winter thinking about what kinds of native plants we want to add to our gardens, my partner and I are always very excited to start germinating seeds and propagating plants. Though we always place the plants at the center of our focus, we would be lying if we said a big part of our gardening obsession wasn’t aimed at attracting wildlife to our property.

There is no denying that gardening, especially with native plants, is the best way to benefit local wildlife in your neighborhood. It doesn’t take much to succeed either. Our landlords are amazing people that allow us a certain degree of freedom to do what we wish with the yard, but they still want to ensure that we maintain something akin to a “traditional” suburban landscape. As such, most of our gardening efforts must be crammed into borders and other highly manicured areas surrounding the lawn. Even so, we are constantly amazed by how much life our plants attract.

I really wish we had the foresight to document insect diversity before we began planting so we could do a before and after comparison, but hindsight is always 20/20. From bees to mantis flies and a hefty population of fireflies, we spend hours each week pursuing the garden to see what kinds of interesting critters are hanging around the yard. The amount of insect life in our garden hasn’t gone unnoticed either.

Leafhoppers and treehoppers are among our favorite insects to see in our gardens.

I remember one afternoon a couple years back, our neighbor approached us to ask if we had seen any bees visiting our tomato plants. Our reply was a very enthusiastic “YES” followed by a rundown of our best estimates on how many different bee species we encountered each day. He seemed a bit bummed and replied that he had yet to see a single bee on his plants. This was a teaching moment that we needed to address as tactfully as possible.

You see, this neighbor is obsessed with mowing and spraying. Save for a few irises near his front porch and two raised beds chock full of tomatoes, no other plants beside grass are allowed to establish on his property. Though completely anecdotal, I can’t help but feel his lack of plants translates in a big way to his lack of bees. We mentioned that all of those “weeds” in our yard that he is always “jokingly” giving us a hard time about are the reason that we have so many bees. Tomato flowers are great but they aren’t around all the time and bees need other food to survive. They also need places to reproduce, which means leaving bare patches of soil around the property and allowing plenty of garden debris in the form of stems, twigs, and leaves to remain in place well into summer.

I am not sure we convinced him to completely change his ways with that conversation, but it definitely got him thinking. He asked if next time we have some spare plants if we wouldn’t mind donating a few so that he can plant them near his tomato beds. We enthusiastically agreed. Though a minor victory, we celebrated the fact that our garden had served as a mini catalyst for a tiny change in someone else’s life.

A firefly stopping for a sip of nectar on one of our common milkweeds (Asclepias syriaca).

With Earth Day coming up this week, the internet is full of quick tips on how to make your life more eco-friendly. There are endless articles available to those looking for advice on green living and sustainable gift ideas. I would like to argue that there is no greener gift than the gift of native plants. It doesn’t matter which species or why, just make sure you pick plants that are native to your region. By establishing native plants in your garden or even in pots on your patio or balcony, you are making a great step in celebrating Earth Day every day. Plants are truly the gift that keeps on giving and you can sleep better at night knowing that they are doing so much more than simply beautifying a space. They are providing food, shelter, and a place to breed for the countless organisms that allow ecosystems to function.

And, as we experienced with our neighbor, native plants can offer so many wonderful moments of inspiration and learning. As I discuss in my book, “In Defense of Plants: An Exploration into the Wonder of Plants,” realizing that native plants and the communities they comprise set the foundation for all other life on this planet set me on a path of wonder and discovery that I have never left. Plants changed my life for the better and by surrounding ourselves with them at all times, my partner and I know that we are doing our part to change the lives of the many organisms struggling to survive in this human-dominated world. So, if you want to live every day like it’s Earth Day, brighten up your life with a few native plants and enjoy all of the wonder and beauty they provide.

Why Plant Relationships Matter for Caterpillars

Photo by Judy Gallagher licensed under CC BY 2.0

When it comes to caterpillars, plant diversity matters. By studying nearly 30,000 plant-caterpillar interactions across three continents (Asia, North America, and Europe), scientists have uncovered important insights into lepidopteran biodiversity in temperate broadleaf forests.

Plants and the caterpillars they host are engaged in an evolutionary arms race. As plants evolve different defenses, caterpillars evolve new ways overcoming them. As you can imagine, studying these intricate relationships can be as fascinating as it is challenging. One could easily spend a lifetime trying to understand the relationships among only a handful of species. However, by taking a step back and asking bigger questions related to evolution and herbivory, scientists have found some interesting patterns than help describe the diversity of plant-caterpillar relationships.

As one might expect, they found that as plant diversity increases, so too does the diversity of caterpillars an ecosystem can support. Many caterpillars specialize on one or only a few different host plants and these are often (though not always) within the same plant family. The reason for this has to do with plant defenses. The more closely related plants are, the more likely they are to share similar defense strategies. For instance, most milkweeds (Asclepias spp.) produce toxic compounds called cardiac glycosides and many different members of the nightshade family (Solanaceae) produce similar suites of toxic alkaloids. As a result, insects that munch on their tissues have similar hurdles to overcome in an evolutionary sense.

The more closely related plants there are in an environment, the more likely it is that the caterpillars they host can jump from one plant species to another. As a result, ecosystems that boast relatively few plant lineages support relatively few caterpillar species in part because the caterpillars they do host can more easily jump from plant species to another. The same logic applies in the opposite direction as well. Ecosystems comprised of a diversity of plant lineages limit the likelihood that any given species of caterpillar can find multiple different hosts. Because each clade of plants produces their own brand of herbivore defenses, the caterpillars hosted by each are also more likely to be different. Thus, as plant diversity goes up, so too do the numbers of caterpillar species an ecosystem can support.

Though not tested by this research, this also provides yet another example of why invasive plants harm biodiversity. Plants from other areas of the world are more likely to present novel defenses to native herbivores. If the caterpillars do not have what it takes to overcome these defenses or simply don’t recognize the plant as food, the fewer caterpillars that ecosystem can support.

Of course, none of this should come as a surprise to those interesting in native plants and gardening. The more indigenous plants you grow in and around your landscape, the more insects you can support. I also firmly believe that the results of this research are not limited to caterpillars. The same pattern likely applies to any number of plant eaters, from microbes to mammals, no matter where you look. What this research gives us are some answers to questions like “why does biodiversity matter?”

Photo Credit: [1]

Further Reading: [1]

American Bittersweet

Photo by Peter Gorman licensed by CC BY-NC-SA 2.0

As the bright colors of fall start to give way to the dreary grays of winter, people often go looking for ways to bring a little bit of botanical color indoors to enjoy. It is around this time of year that one species in particular starts turning up in flower arrangements, however, it's not the flowers people are interested in but rather the seeds. This species is so popular in arrangements that its numbers in the wild are facing steep declines.

Meet Celastrus scandens, the American bittersweet vine. It hails from the family Celastraceae, which makes it a distant cousins of Euonymus. This lovely climbing vine is native to much to eastern North America and is most at home growing at the edge of woodlots, thickets, and along rocky bluffs and outcroppings. As mentioned, It isn't the flowers of this species that catch the eye but rather the showy seeds. Encased in bright orange capsules, the crimson berry-like fruits are toxic to us mammals but highly sought after by birds. Despite their toxicity, humans nonetheless covet these fruits. Entire vines are cut down and used in arrangements, especially during the months of fall. This has had detrimental effects on wild populations of American bittersweet.

To add insult to injury, its Asian cousin, Celastrus orbiculatus, has been introduced to this continent and is running amuck in the wild. Known commonly as Oriental bittersweet, this invasive is quickly outpacing its native cousin throughout much of North America. It would seem that Oriental bittersweet can adapt to a wider range of habitat types than American bittersweet and, where these species co-occur, hybridization has been reported. The hybrid offspring are not only fertile, they also have shorter seed dormancy and are much more vigorous growers than either of the parents.

Photo by MN Department of Agriculture

Unfortunately it can be hard to tell these species apart. However, with a little patience and a decent field guide, differences become apparent. The best diagnostic feature I have found is that American bittersweet carries its flowers and fruit on the terminal ends of the stems whereas Oriental bittersweet carries them in the axils of the leaves.

All in all, American bittersweet is a lovely native vine. Its beauty in our eyes has, like so many other plant species, created some serious survival issues. Coupled with the the threat of its highly aggressive Asian cousin, the future of this wonderful species remains uncertain. That being said, this doesn’t have to remain a trend. The good news is that it does quite well as a garden species and many nurseries are beginning to carry the native over the invasive. If you live in eastern North America, consider using this plant in your landscape. It would certainly help. And, if flower arrangements are something you enjoy, please give American bittersweet a break.

Photo Credits: [1] [2] [3] [4]

Further Reading: [1] [2] [3] [4] [5]

North America's Pachysandra

Photo by Salicyna licensed under CC BY-SA 4.0

In the interest of full disclosure, I have never been a fan of garden variety Pachysandra. Long before I had any interest in plants or gardening, there was something about this groundcover that simply did not appeal to me. Fast forward more than a decade and my views on the use of Asian Pachysandra in the garden have not changed much. You can imagine my surprise then when I learned that North America has its own representative of this genus - the Allegheny spurge (Pachysandra procumbens).

My introduction to P. procumbens happened during a tour of the Highlands Botanical Garden in Highlands, North Carolina. I recognized its shape and my initial reaction was alarm that a garden specializing in native plants would showcase a non-native species. My worry was quickly put to rest as the sign informed me that this lovely groundcover was in fact indigenous to this region. Indeed, P. procumbens can be found growing in shady forest soils from North Carolina down to Florida and Texas.

Photo by David J. Stang licensed under CC BY-SA 4.0

This species is yet another representative of a curious disjunction in major plant lineages between North America and eastern Asia. Whereas North America has this single species of Pachysandra, eastern Asia boasts two, P. axillaris and P. terminalis. Such a large gap in the distribution of this genus (as well as many others) seems a bit strange until one considered the biogeographic history of the two continents.

Many thousands of years ago, sea levels were much lower than they are today. This exposed land bridges between continents which today are hundreds of feet under water. During favorable climatic periods, Asia and North America likely shared a considerable amount of their respective floras, a fact we still find evidence of today. The Pachysandra are but one example of a once connected distribution that has been fragmented by subsequent sea level rise. Fossil records of Pachysandra have been found in regions of British Columbia, Washington, Oregon, Wyoming, and North and South Dakota and provide further confirmation of this.

As a species, P. procumbens is considered a subshrub. It is slow growing but given time, populations can grow to impressive sizes. In spring, numerous fragrant, white flower spikes emerge that are slowly eclipsed by the flush of spring leaf growth. The flowers themselves are intriguing structures worthy of close inspection. Their robust form is what gives this genus its name. "Pachys" is Greek for thick and "andros" is Greek for male, which refers to the thickened filaments that support the anthers.

It is hard to say for sure why this species is not as popular in horticulture as its Asian cousins. It tolerates a wide variety of soil types and does well in shade. What's more, it is mostly ignored by all but the hungriest of deer. And, at the end of the day, it took this species to change my mind about Pachysandra. After all, each and every species has a story to tell.

Photo Credits: [1] [2]

Further Reading: [1] [2]

Meet the Sweetfern

Photo by Sten Porse licensed under CC BY-SA 3.0

I remember the first time I laid my eyes on Comptonia peregrina. I was new to botany at that point in my life so I didn't have a well developed search image for these sorts of things. I was scrambling down a dry ridge with a scattered overstory of gnarly looking chestnut oaks when I saw a streak of green just below me on a sandy outcropping. They were odd looking plants, the likes of which I had never seen before.

I took out my binoculars to get a better look. What were these strange organisms? Were they ferns? No, they seemed to have woody stems. Were they gymnosperms? No, I could make out what appeared to be male catkins. Luckily I never leave home without a field guide or two. Using what little terminology I knew, I was able to narrow my focus to a plant commonly called a "sweetfern."

Photo by Megan Hansen licensed under CC BY-SA 2.0

This was one of the first instances in which I grasped just how troublesome common names can be. C. peregrina is mostly definitely not a fern. It is actually an angiosperm that hails from the bay family (Myricaceae). Comptonia is a monotypic genus, with C. peregrina being the only species. It is a denizen of dry, nutrient poor habitats. As such, it has some wonderful adaptations to deal with these conditions.

To start with, its a nitrogen fixer. Similar to legumes, it forms nodules on its roots that house specialized nitrogen-fixing bacteria called rhizobia. This partnership takes care of its nitrogen needs, but what about others? One study found that not only do the roots form nodules, they also form dense cluster roots. Oddly, closer observation found that these clusters were not associated with mycorrhizal fungi. What's more, they also found that these structures were most prevalent in highly disturbed soils. It is thought that this is one way that the plant can maximize its uptake of phosphorus under the harshest growing conditions. 

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Photo by Jomegat licensed under CC BY-SA 3.0

Flowering in this species is not a showy event. C. peregrina can be monoecious or dioecious, producing male and female catkins towards the ends of its shoots. After fertilization, seeds develop inside bristly fruits. Seed banking appears to be an important reproductive strategy for this species. One study found that germinated seeds had lain dormant in the soil for over 70 years until disturbance opened up the canopy above. It is expected that seeds of this species could exhibit dormancy periods of a century or more. 

In total, this is one spectacular species. Not only does it have a unique appearance, it is also extremely hardy and an excellent species to plant in drought-prone soils wherever it is native. I do see it in landscaping from time to time. If you encounter this species in the wild, take the time to observe it in detail. You will be happy you did!

Photo Credits: [1] [2] [3]

Further Reading: [1] [2] [3]

So Many Goldenrods, So Little Time

Nothing says late summer quite like the blooming of the goldenrods. These conspicuous members of the aster family get a bad rap because many folks blame them for causing hay fever. This is simply not true! In this video we take a closer look at a small handful of goldenrods as a way of celebrating this ecologically important group.

Music by: Artist: Ampacity

Track: Encounter One

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In Search of a Parasitic Orchid

In this episode, In Defense of Plants goes looking for a tiny parasitic orchid called the autumn coralroot (Corallorhiza odontorhiza - http://bit.ly/2xQhzbc). It has no leaves and does not photosynthesize. Instead, it makes its living completely off of mycorrhizal fungi, digesting its hyphae within the cells of its highly derived roots. Along the way we meet plants such as:

 Music by: Artist: Ampacity

Track: Asimov's Sideburns

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In Search of Spring Wildflowers

In this episode we are exploring a small park located in central Illinois in hopes of finding spring wildflowers. Will we find any? Watch a find out ;)

Producer, Editor, Camera:
Grant Czadzeck (www.grantczadzeck.com)

Growing Ferns

I am finally having some success intentionally growing ferns from spores. I collected and sowed spores from some interrupted ferns (Osmunda claytoniana) over the summer. They have been hanging out as gametophytes for months now and some are finally starting to grow sporophytes. Here is how it worked for me:

I kept my eye on a batch of adult plants this summer. Once their fertile fronds developed I would flick them every now and then to see if they were releasing spores. Once I saw that they were I shook the fronds over some paper to collect the spores. I then took some old potting soil and sterilized it with boiling distilled water. I use old takeout containers because they are small and have clear lids that form a seal which keeps the humidity high.

Once the soil was cool I sprinkled the spores over it and then placed it on a shelf where it gets a small amount of ambient light every day. The rest they did themselves. You just have to remember to check on them and keep the humidity quite high because they can dry out really fast. They seemed stuck as gametophytes for months. I just noticed the start of these sporophytes the other day.