Finding Featherbells

After seeing some early spring wildflowers pop up at my house, I decided to venture out and see if others were rising up out of the post-winter fray. One that I want to check right up the road from me was Stenanthium gramineum or feather bells.

I saw it last year blooming right along the roadside. This species is a new one that I've learned about since moving to Texas. It is closely allied to the death camas (Zigadenus) that I saw years ago in the Green Swamp.

I love its feathery flowers, which resemble miniature lilies with their petaloid floral parts. And, until I wrote this post I realized I actually don’t have any photos of the plant in flower. I promise I’ll get you some later this spring.

It was a challenge locating them at first. The leaf blades resemble grass, hence the epithet graminieum. A Tradescantia fooled me at first, but there was way too much pubescence on the foliage. Finally, I found their smooth leaves rising from the leaf litter with the dark magenta sheath near the base. Sometimes it's hard to remember where you saw something last year!

I feel bad for these plants because they get cut down every July when the roadcrews do their mowing. But, they are doing better than the plant at my house a colleague gifted me two years ago that hasn’t even bloomed yet. I moved it recently to a sunnier spot in hopes that I might see some inflorescences this year. We’ll have to wait and see.

The Stenanthium gramineum my colleague gifted me excavated so that you can see the lovely magenta sheaths at the base.

My Planting for a Monarch

I’m getting antsy.  Spring is on its way.  The weather lately has been in the 60’s and 70’s, Narcissus and Muscari are in bloom, and dormant perennials are popping out of the ground.  Sure, we’ll have a few more frosts (maybe a freeze?), but being just a few weeks away from the first official day of spring, this gardening season is about to get goin’ and growin’.

One goal I have this year is to finalize the design of a few beds near our garage.  They’ve been mostly a holding cell for potted plants that right after we bought the house I plopped into the ground to save from incessant August watering.  

In my mental iterations of design, I’m not only considering beauty, harmony, and seasonality for these plantings but also management, survival strategies, and the benefits to insects and wildlife.  The critters seem to get the short end of the straw when planting versus the elements of design, but that seems to be changing with the increase of the public’s awareness of ecology and our role to make the world a better (or, if we don’t act a worse...) place.  

Many people believe that to have a garden good for wildlife your yard has to more closely resemble an unmown field, but what if I told you research shows that making a few small changes to the way you plant could help increase an insect’s survival and even perhaps their numbers?  

That’s what the recent paper “Configuration and Location of Small Urban Gardens Affect Colonization by Monarch Butterflies” by Adam Baker and Daniel Potter in Frontiers in Ecology and Evolution indicates.  It’s a technical title, but the basic hypothesis they tested was does the way we plant Asclepias (milkweed) species impact how Monarchs can find the plants and subsequently lay eggs on them?  

And, yippie! The whole paper is available online for people to read. I really enjoyed diving into this paper.  The research was broken down into three parts—investigating Monarch waystation gardens, synthesizing planting configurations, and looking at surrounding vegetation.  And, I have used their figures only to help you understand their work. All credit for the following figures goes to these researchers.

MONARCH WAYSTATIONS

For the Monarch waystation gardens, they visited 22 gardens that contained three species of Asclepias (A. incarnata, A. syriaca, and A. tuberosa).  They asked two great questions about each garden—were the plants blocked or mixed, and can Monarchs see the plants on a north-south approach.  

The former question is interesting from a naturalistic planting perspective because blocking versus mixing are two different approaches for laying out plants.  Oudolf and Kingsbury go in greater detail about both approaches in their book Planting: A New Perspective.  In my mind, if you had asked me before this study which would be better for insect populations, I would have said mixed.  A diverse habitat has been shown to support more species (more on this theory in a minute).  But, the research showed that these blocked or as they called them structured plantings had more Monarchs and eggs on them than the mixed plantings.  

In these waystations, they also evaluated whether plants could be accessed along a north-south gradient. Monarchs fly north from overwintering in Mexico, and then they fly south at the end of the growing season.  And, while the paper does say that they can fly any direction in a garden, planting Asclepias so they are visible in this north-south migration path seems to increase the number of Monarchs encountered and eggs laid on plants.  

This figure from from Baker and Potter’s (2019) paper shows that gardens that had structured (aka blocked) Ascelpias had more Monarchs than non-structured (aka mixed) plantings! Additionally, gardens that featured Asclepias that could be viewed on a north-south trajectory had more Monarchs as well. Note: ramet is a fancy word used to describe the number of shoots from a clonal colony. So, if an Asclepias plant has 10 shoots, those are 10 ramets.

PLANTING CONFIGURATIONS

A second step they took in their research was to create three different planting modules for evaluating Monarch counts—Asclepias on the perimeter, Asclepias in the middle, and Asclepias in a mixed planting.  All three gardens contained the same number of plants and fillers like nectar-rich Tithonia rotundifolia and Zinnia elegans and the tall ornamental grass Calamagrostis × acutiflora. 

Here’s a figure I pulled from Baker and Potter’s (2019) work that helps to illustrate their planting configurations.

Again, if you asked me before reading this, I would have guessed that the mixed planting would be the best.  But, their two years of data collection showed that the perimeter plantings had roughly DOUBLE TO QUADRUPLE the number of eggs and larvae as the other two plantings.  Wow.  I was blown away.  They cite a whole plethora of reasons and that having non-host plants (like the Zinnia, Calamagrostis, and Tithonia) might interfere with egg laying by Monarchs onto the host-plant Asclepias—blocking, shading, mixing volatiles, and landing on the wrong plant too many times. And, it appears that if enough of these compound together, the number of eggs and larvae on plants are drastically reduced.

And, here’s Baker and Potter’s (2019) data of Monarch eggs and larvae counts from those planting configurations. Absolutely amazing. Asclepias that were on the perimeter had double to quadruple the number of Monarch youngsters.

I mentioned earlier that increasing diversity (like we see in mixed plantings) can potentially help to support more insects.  What if the mixed configuration had more predatory insects?  They thought of that by trapping predatory insects and noted they didn’t really see a difference between the perimeter and mixed configurations.  Thus, there weren’t insects reducing the numbers of Monarchs in the mixed configuration relative to the perimeter planting.  

Basically, they created an unimpeded monoculture for the Monarchs.  We talk about how monocultures are bad because a group of plants en masse can have more pests than being mixed in a polyculture, but this research flipped that thinking on its head.  That if you want to plant something for a desirable “pest”, then block it and put it where they can see it.  

They do make a note in the discussion about the perimeter plantings. Because the between plant distances were greater in the perimeter planting and because Monarchs do prefer to lay eggs on isolated plants, this effect may have had an influence.

ASCLEPIAS HIDE AND SEEK

The last experiment they did was to investigate effects of surrounding vegetation over two weeks.  They planted Asclepias incarnata by itself and then hidden by Panicum virgatum ‘Shenandoah’.  The two plants didn’t touch (mind your bubble, switchgrass!), but the Pancium were close enough to hide the plants.  They observed that unimpeded Asclepias plants had on average a little over three eggs per plant while those screened by the Panicum had nearly zero eggs.  

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So, the things I took away from this paper about planting for Monarchs:

• Plant Asclepias in blocks with adequate spacing between plants.

• Plant Asclepias so that Monarchs have north-south access to the plants.  

• Plant Asclepias on the edges of your garden.

• Plant Asclepias so that surrounding vegetation doesn’t hinder access to the plants.  

And, that’s how I’m going to do it.  I have some locally sourced Asclepias seed, and once I get the plants going, I’m going to plant them in a couple of blocks on the outside of my beds with a few mixed in here and there for harmony.  

Now, the question is does this approach also work for other insects?  Of course, it would take more research to answer that question.  Some insects don’t migrate; therefore, the north-south access might be less important for them.  But, I do think that locating host-plant species near the edge, in blocks, and making sure they are accessible could be extrapolated to planting for other species of insects.  

A final note.  I don’t usually set down and digest a scientific article like this, but I was so impressed by the research and the content that I had to share it.  If you like this reflection writing, let me know, and I’ll consider doing more in the future.   

A Swell Swale

One of the big projects that I’ve worked on over the past year at our house is the construction of a swale in our vegetable patch and a dry creek bed that connects into it from the east across our property. These are fancy words to describe a glorified ditch.

When we first moved into the house, I didn’t realize that I had built my vegetable garden where water courses through our property. I guess that goes to show the wisdom of waiting a year or so before making drastic changes to a property so that the whole gamut of how things will shift can be seen.

Oh, well. I couldn’t wait, and here I am now. Last week, I finished up widening the swale in the vegetable patch. It is now 3 feet wide and slightly elevated on either side to help hold a little extra water. But, I’ve realized that with very heavy rains like the 6 inches we got last May, the swale will likely break it’s banks, but I’m designing some overflow beds for that.

Either side of the swale is being planted with stock perennials and Vaccinium that will enjoy the wetter feet. I’ve also sowed white clover as a groundcover to hold the soil on the banks, and it is doing a spectacular job so far this winter. I may have to plant some other wet-tolerant species like Juncus to carpet the ground in the swale. It dries up to a crisp during the summer, so it may serve as a growing ground for other crops.

But, now in the winter, it is a stream for me to enjoy the trickle of water.

Winter Botanizing in East Texas

I joined Peter Loos and Dawn Stover on a recent botanizing trip in early January to look at some of some rare native flora in east Texas.  Tagging along with us were Jordan Cunningham, Dawn’s greenhouse assistant, and Cole Gandy, a horticulture graduate student.  

SEEDS OF A BOTTLE

Our first target for the day was Gentiana saponaria, the soapwort gentian.  While plentiful back east, it is very rare in Texas. Naturalist Matt Buckingham stated that there may only be five populations in Texas.

Gentiana saponaria habitat in east Texas.

While the plants bloomed back in November and December, our quest today was to ascertain the seed set on them.  We arrived at our site far down a logging road under gray skies on a warmish winter day.  Dawn and Peter had flagged plants back when they were in bloom, and now we could check pollination success.  

While many flowers had no seed, some did.  Gentiana saponaria is a bottle gentian, named because the tops are closed and require a pollinator like a bumblebee to force them open.  Dawn found a capsule split above a flower and pointed out to me how interesting the seed dispersal was.  We looked at some seeds closer up.  They were as fine as dust and resembled teardrops.  At the time, I thought it odd as to how the capsule got above the spent flower.   Once I got home I would discover that once pollinated the pedicle of the flower actually elongates so that the seed can find a new home.  We checked approximately 25 plants, but I’d say we only observed seed on about 7 of them. 

A hint of color left on this Gentiana saponaria

Once pollinated, the pedicel elongates to disperse the next generation. If you look closely at the base of the V, you can see the dusty, white seed.

Here’s a close up of a damaged seed pod. Notice how fine the seed are.

Peter Loos checks a Gentiana saponaria for seeds. Many grew on the sides of the creek.

Most of the plants that we looked at were either clinging to the edge of the stream or within 20 feet of it.  The stream likely acts as a refugium for this species, providing water and perhaps a fire break to prevent reproductive damage.  Peter commented to Cole that later in life he should come back and see if the gentians are still here.  We certainly hope so, but this species is likely a relic from when Texas was much cooler and wetter.  If the climate continues its warming and drying trend, gentians may one day be absent from Texas.  That is why these investigations into the reproductive success of Gentiana saponaria are important.  Dawn and Peter’s work is trying to prevent their demise and preserve the genetics of this southwestern population.

WITCHHAZEL HUNT

The second species, and one that I have wanted to see for some time, was Hamamelis ovalis, the big-leaf witchhazel.  I’m a witchhazel nut, and I wish so much that we could grow many of the hybrids in Texas.  But, alas they struggle in the deep south due to our lack of chilling hours.

The other reason I was excited to see this species is because it is fairly new to science.  In 2004, Steve Leonard found what would become Hamamelis ovalis in Mississippi. He noted even though it had similar red-to-yellow flowers and bloom time to Hamamelis vernalis that occurs in the Ozarks, it was about 600 miles further south.  And, while this witchhazel distribution overlapped with Hamamelis virginiana in the Mississippi locale, this species had larger leaves and tomentose (aka fuzzy) undersides to the leaf.  He published the name and description along with a great write up in Sida, Contributions to Botany in 2006. Then, in 2009 Wayne Webb found a population of these plants in Alabama, and since then it has been found in a total of five counties in Alabama.

Peter said that he had been shown this Hamamelis by Lynn Lowery in mid-1980 when these populations in east Texas were classified as disjunct occurrence of Hamamelis vernalis.  Later, Peter found additional sites like the ones we saw last May on our class outing, and it was sometime around 2010 after Hamamelis ovalis was named that he began to suspect that what occurred in Texas was actually Hamamelis ovalis all along. He and other native plant experts in the area have come to the same conclusion.  

Even though it may only occur in a handful of places in the southeast, this southern species deserves wider use. Hardiness further north doesn’t seem to be much of an issue. There are specimens in the Arnold Arboretum in Massachusetts (zone 6b).

Hamamelis ovalis begins flowering in the wilds of east Texas. Their strap-like (aka ligulate) petals unfurling reminds me of octopus tentacles.

We parked on a logging road, and clambered up the hillside of the right-of-way to find a dense thicket of trees.  Right inside was a wide10-foot-tall Hamamelis ovalis just starting to put on a show.  The flowers were smaller, just like the rest of its native cousins. However, they were colorful, and many individuals reminded me of the coloration you see on ‘Jelena’ or ‘Wisley Surpreme’.  Peter commented that we were early.  Last year when he visited, he could see the large tree through the brush from the other side of the road. 

I had read online another identifying feature is to tug on the new shoots around the base.  On Hamamelis ovalis, they will give some, and sure enough branches did rise up from the ground with a gentle heave.  My hands moved from a larger branch to a smaller pencil-thin whip and I noticed an abundance of pubescence.  As far as fragrance, it varied specimen to specimen.  Some you would catch that sweet witchhazel smell while others had little if any scent.  

As we explored the population, Peter pointed out a large colony of Texas leaf cutter ants and commented that they had been there as long as he has been visiting this site.  The space the mounds occupied could have easily fit into two or three parking spots.  He joked, “This time of year, yaupon holly is about all you’ll see around the holes.  They’re caffeine addicts!”  

A Texas leaf cutter ant mound. Notice the abandoned shreds of Ilex vomitoria.

A minute or two later as I was photographing a witchhazel I noticed one of the ligulate petals moving.  A leaf cutter ant was hauling it away!!!  I gave a little squeal at seeing this little marvel of nature. Seems we humans are not the only creatures that enjoys the blooms.  

A Texas leaf cutter ant carries a witchhazel petal.

Having seen the diversity at this site, we got back in our cars, and drove down the road a bit to a second Hamamelis ovalis site at a local trail.  We walked about half a mile to a see a second population, passing emerging Trillium and a forest that more closely resembled the east coast than Texas.  

Early Trillium foliage rises from the leaf litter.

We reached a spot in the trail where more light came through the bare canopy.  At first, all we could find was small Hamamelis saplings, but before we left I was spotting small trees 12-to-15 feet tall with their blooms high above.  Peter said that many of the runts were likely small due to dense shade from the canopy, but a storm a few years ago removed some branches and opened it up for more light to reach the forest floor. 

One of the taller big-leaf witchhazels. You can see the blooms against the darker colored tree trunks.

While we noticed more interesting color variants (even a yellow flowering one!), it was here that I really started to see some clonal nature to this species.  Two specimens a few feet apart would have the same color pattern, or you could see at another colony where two seemed to grow out from the same spot yet be a few feet apart.  Another gentle yank on some showed me the plants had layered on the forest floor.  

This clone faded from red to orange to yellow in the petal.

A more orange colored form.

We even found a yellow flowering big-leaf witchhazel!

At this second location, I also saw Hamamelis ovalis exhibiting a common characteristic to witchhazels, marcescent foliage. It varied from clump to clump as far as how many leaves were retained, but in general most of them were deciduous.

We headed back to the cars from a day full of botanizing and learning more about the flora of Texas.  Even in the dead of winter there are plants to be enjoyed, and with a better understanding of soapwort gentian and big-leaf witchhazel, I hope these jewels of the winter landscape can be preserved and continue to shine for many years to come.

One final glimpse of big-leaf witchhazel in flower. What rich color for a gray day!

No, you shouldn’t plant trees in square holes, AND it is 26% more work for you.

Planting a tree is a great way to celebrate the new year and the new decade.  Heaven knows, I’ve got a few that I need to get in the ground or move from one spot to another.  

But, recently, I’ve seen the article on the interwebs about planting trees in square holes.  It appears that most of them originated from this article in The Guardian by James Wong on 8 December 2019.    

A quick google search reveals that Intelligent Living also featured the idea. Also, Sunset picked up the theory and ran with it. They even made a meme about Sir Joseph Hooker stating he planted in square holes even though the source The Gardener’s Assistant they shared was written by Robert Thompson in 1859 (page 405 in case it doesn’t hyperlink). Le sigh…

Poor Sir Joseph Hooker, never gets any respect.

But, the problem is there is no scientific literature that supports this information.  I applaud Sunset for at least finding The Gardener’s Assistant where Thompson stated that he plants in square holes. But, again, there is no research to back this statement up. Also, to show how dated it is, Thompson calls roots spongioles. Ew.

Back to the original article. Wong states,

“...in recent decades scientific research has overhauled much of the traditional wisdom about planting saplings, including some ideas that sound a little strange. ”

I agree with this statement.  As a scientist, I love data and results from replicated trials, and new work is constantly shedding light on the wonderful world of plants.  But, here’s where the article get murky.  

“So, let me explain why science proves that it’s better to plant trees in square holes. ... here’s what happens to the tree’s roots when you plant them in a round hole, especially one filled with lots of rich compost and fertiliser, as the old guide books suggest. The little sapling will rapidly start growing new roots that will spread out into the rich, fluffy growing media, giving you excellent early success. However, once they hit the comparatively poorer and compacted soil at the perimeter of the hole, the roots will react by snaking along the edge of the hole’s edge in search of more ideal growing conditions.

Eventually, this spiralling action around the limits of the hole will create a circular root system, with the plants essentially acting much as they do when grown in a container. Once the roots mature they will thicken and harden into a tight ring, creating an underground girdle that will choke the plant, eventually resulting in the severe stunting and even death of your treasured tree.

The very simple and counterintuitive act of digging a square planting hole will dramatically reduce the chances of this happening. This is because systematic planting trials have shown that roots are not that good at growing round corners. When they hit the tight, 90-degree angle of your square hole, instead of sneaking around to create a spiral, they flare out of the planting hole to colonise the native soil.”

Yes, many old sources say to enrich holes.  I agree with Wong; that is wrong.  It is better to back fill with the original soil with few to no amendments and apply amendments to the topsoil so that the entire area around benefits, not just the hole.  But, we can’t make a jump from it is wrong to enrich the soil to it is wrong to plant trees in circular holes. The article states,

“This [planting is square holes] has been shown consistently to speed up tree establishment and make the specimens more resistant to environmental challenges, such as drought.”

Who is showing this?  Show me the data!  SHOW ME THE DATA!!! The only thing I can even find from a quick search is an RHS article where planting in a square hole is briefly mentioned as a sidenote along with photos in an article where they are planting trees in… you guessed it. Circular holes.

***NOTE: After this post was written, a discussion on Facebook began, and Dr. Marc van Iersel shared this article, which showed there was no benefit from planting trees in cube, cylinder (scarified and non-scarified), star, or sloped cylinder holes. There is a note that sloped cylinder could be better in dry planting locations.

What kills me is the article does not focus on the core problem of circling, girdling roots!!!  It’s just a side note. 

“While you are at it, prune any twisted or matted roots from the edge of the root ball before you plant the sapling.”

YESSSS!!! Preach, brother. When plants grow in nursery containers, their roots hit the wall and begin to grow in a circle.  (Sidenote: Some pots have different designs like slits or sharp corners to reduce this growth, but the majority don’t.)  

Roots on woody species are different from many annuals and perennials in that they are permanent.  Once a tree has grown a root into the soil, unless the root dies, it will continue to get larger and larger.  So, now we have a circular root increasing in girth near the base of the tree.  The tree base and trunk are also growing wider, eventually the roots and trunk touch, and the roots can girdle the tree.  

Classic example of a girdling root. This tree has survived, but many don’t. This tree will likely become stressed over time due to the roots so close to the trunk.

I ran into this when I planted three persimmon trees at my house last winter.  The roots were circling and malformed right out of the pots; therefore, I disturbed them to make sure they would be able to grow out and live long instead of round for the rest their short life.  

Here’s some more great info on girdling roots and correct RESEARCH-BASED tree planting methods.

Fraedrich, B.R. No date. Research laboratory technical report: Girdling roots.

Johnson, G.R. and R.J. Hauer. A practitioner’s guide to stem girdling roots of trees: Impacts on trees, symptomology, and prevention. University of Minnesota, St. Paul, MN.

Urban, J. 2013. The root of the problem. Landscape Architecture Magazine, April:54–58.

MATH IS OUR FRIEND

The other thing that bothers me about this article is planting a square hole is HARDER than planting a circular hole.   I’m not opposed to investing effort in planting trees or performing tasks that research shows to be beneficial.  Like breaking up a rootball before planting or mulching a wide area around the tree after planting.  Those are techniques that research has shown can drastically improve the tree’s success.

The article states,

“Considering that spade blades are flat, digging a square hole, to me at least, seems far easier than cutting a perfectly circular one. It’s an easy win-win.”

First, who can dig a perfectly shaped square better than a circle?  Second, math says square holes will be more back breaking.

Let’s say I have to dig a three-foot-diameter hole for a tree like I did when I recently moved a very small Magnolia at our house.  From a simple area calculation I did, you will now be excavating 26% more soil digging a square hole.  That means you dig out 26% more, you fill back in 26% more, and it is taking you longer.   (Note:  If you do a volume-based calculation using cylinder and prism formulas, you’ll get the same ~26% since they both extend at the same increase.)

Math doesn’t lie.

Some may argue that the 26% extra increase in disturbance is going to help roots grow out.  And, in some compacted soils that may be true. But, y’all, roots have been growing through soil a lot longer than we’ve been planting them.  I trust that once you get a tree in decent soil, as long as it doesn’t have girdling roots it will be just fine.  

THE ROOT OF THE PROBLEM

Do I think James Wong or Sunset maliciously posted this article?  No, I really think that they were trying to give wise advice on how to make trees live longer to beautify our world.  With maybe a dash of click-bait.

The problem is we live in a world where someone can say something, and people believe it to be true.  Take the following examples.  

• Vaccines are harmful.  

• Buy more things to be happy.

• The media is bad.  

• Epsom salts will solve any plant problem.  

• Jared Barnes is the worst horticulturist in the world.  

Just because someone says something doesn’t mean it’s true, and many of the above points have been disproven or the result of lies spread round.  Especially point number 5 there.  

I applaud the people who have asked me and the people who have asked others on social media is this myth accurate?  Hooray!  You get a gold star.  This article is yet another symptom of our culture where we don’t think and we go along with what information is put in front of us.  

I’ve read Thinking, Fast and Slow by Daniel Kahneman, and in that book he makes the case that we have two mental systems for processing information.  System 1 is quick, fast, and intuitive.  System 2 is more analytical but slower and lazier. 

An example from the book.  If I say, “what’s 2 × 2?” you can’t stop thinking the number 4.  It is automatic and effortless.

But, if I ask you what’s 37 × 48, it takes you a while to realize that it’s 1,646.  You don’t instinctively know that because you need to activate your system 2 to do the calculation or expend effort plugging it into a calculator.  

Except, it’s not the correct answer.  The true answer is 1,776.  I just exploited your system 1.  I told you something, and you took it at face value without even questioning it.  

It makes sense that we have a system 1 evolutionarily.  So much is thrown at us we can’t be expending energy at every neuron firing to process our environment.  

But, I believe that we need to start employing our system 2 more.  We need to train ourselves to pause, digest the information put in front of us, and dig a little—circle or square, hehe—to understand it.  I teach all of my students these system 1 and system 2 learning concepts so they will be more prepared to engage with the world.  As Ms. Frizzle said, “Ask questions.  Make mistakes.  Get messy.” 

I ask you to challenge even my blog post.  Do my sources make sense?  Is my math right?  Is my argument valid? 

Use your system two.  And, go plant a tree.  In a circular hole.