Say Hi to Hymenopappus artemisiifolius

Spring is a ripe time to enjoy self sowers and volunteers like Papaver, Nigella, Centaurea, Consolida, and more.   I believe Hymenopappus artimissifolius belongs in with that bunch.  It’s a mouthful to say for such a lovely ruderal.  Old plainsman is the common name—so wise sounding for such a short lived plant.  

After we bought our house, I noticed this tall white flower on the roadsides near our house and wondered what delightful plant it was.  From a distance in bud it looks a bit like ping pong balls on a gray-green stick.  But, upon closer inspection you find a flower that resembles Astrantia.  There’s even hints of pink in it.  They are from two different families as Astrantia is Apiaceae, and Hymenopappus is Asteraceae.

I’m happy I live an an area where it occurs. This native’s range is limited to three states—Texas, Louisiana, and the southwest corner of Arksansas. But, it deserves wider use. Since it’s a biennial, my only concern is the hardiness of the basal rosettes. I have seen some germinate in late winter. Perhaps this late planting is an option for those who wish to try it further north.

Such lovely Astrantia like flowers. Note the white phyllaries, or modified showy bracts.

Unlike most of the self sowers, the color on old plainsman comes from modified bracts (also called phyllaries) instead of petals or ray florets.  Therefore, the essence of the plant appearing in flower lasts for much longer.  And, its height is much desired early in the season. I believe that both these contenders make the case that it is a great candidate for being a scatter plant in a naturalistic planting.

I haven’t quite figured out the germination requirements for this plant yet.  I scattered what little seed I had last year, and it seems I’ve had better success getting it to grow in our turf than the beds where I want it to reside.  But, once I do, you can be sure that I’ll have tons of it growing in my garden.  

Here’s a photo of the basal rosette of Hymenopappus artemisiifolius. One can barely see the discolor between the green tops and the silvery leaf bottoms.

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.   

Pin the Plant on the Triangle

This semester, one of the classes I’m teaching is herbaceous plants, and I’m taking the class beyond the usual discussions of annuals and perennials.  From studying herbaceous plant communities, one of the most useful concepts that I’ve learned in recent years is the classification of a plant’s survival strategies.  

I’ve written about it before here and here.  As a refresher, Grime pitched that plants had three strategies based on environmental factors.  

• COMPETITORS are plants that take advantages of any and all resources they can muster.  They grow tall and wide to take out the competition.  Usually these stalwarts are perennial in nature, and they grow where stress and disturbance are nil.

• STRESS-TOLERATORS are plants that have adaptations to ensure survival when stress arises and conditions deteriorate.  They are usually perennial and can take many years to flower from seed.

• RUDERALS are short-lived annuals or biennials that are frequently exposed to some type of disturbance, which has selected for plants that quickly produce seed.

Usually, this strategy is visualized using a triangle (much like the soil texture triangle!) where a certain species can be shown to be—pulling some numbers out of the air—say, 70% competitor, 20% ruderal, and 10% stress tolerator based on the characteristics they exhibit.  

A figure of Grime’s triangle from Pierre et al. (2017) titled A global method for calculating plant CSR ecological strategies applied across biomes world-wide. As you can see the authors attempted to classify plants across the globe based on their tendency to be a competitor, stress-tolerator, or ruderal.

How do you take this concept from theory to application for students? Much research and data collection is needed to be able to precisely place a plant on the triangle.  Can it be done in a more simple fashion?  

After we covered the CSR theory in class, I did an activity with students.  I gave small groups (three to four) a list of seven different herbaceous plants and asked them to look up information and pictures online and try to determine where on Grime’s triangle it would fit.  I drew a triangle on the board labeling the sides and gave them markers and half sheets of paper for writing plant names.  

I then challenged them in pin-the-tail-on-the-donkey fashion (no blindfolds or sharp objects though!) to figure out where on the triangle the species would go by searching for it online.  Students looked for tendencies to spread, cover large areas, form large clumps, and/or have rhizomes (COMPETITOR); tendencies to produce copious amounts of seed, occur in areas of disturbance, and/or be short lived (RUDERAL); and tendencies to live in a stressful habitat, take a long time to flower, and/or have storage organs (STRESS-TOLERATOR).

One by one they started coming up and making educated guesses.  I stood by the triangle to offer advice and suggestions.  Some hit the nail on the head while others needed a little bit of coaxing to the right place.  

At the end, we went over the 20 or so species I provided as a challenge.  Again, I explained that while some species neatly fit into one group, some straddle the fence like Liatris elegans.  It has a corm (a stem-derived storage organ indicating some level of stress toleration) yet produces copious amounts of seed (traits of a ruderal).  

Pin the plant on the triangle—a fun game to teach students about plant survival strategies. Based on your plant knowledge, how do you think they did?

As gardeners it’s very helpful to think about flora in this way.  It helps us anticipate how plants will perform.  It explains why Gaillardia and Aquilegia don’t live long as perennials (ruderals), why Mentha and Monarda spread like crazy (competitors), and why Trillium and Narcissus  take 3–7 years to flower from seed (stress-tolerators).   It also allows us to envision how to combine plants.  Maybe put that runaway competitor in a drier spot to keep it from taking over creation?  Or, sow some ruderals in between the stress-tolerators to keep weeds down.  

If students can decide approximately which section of the triangle plants fit in during a 15 minute activity using search engines, then we can by watching how plants grow over the course of a year. 

So, that’s your homework for the season. Draw a triangle and see if you can’t plot where the species in your garden fit.

Mowing the Food Prairies

Today, we mowed the food prairies, our prototype herbaceous plantings at SFA.  I was hoping to wait till January 22nd to have a lab the first week of class and teach students about mowing naturalistic plantings.  However, with the warm weather the underplanted Narcissus × odorus had flower buds emerging from the soil.  This problem is one I outlined in detail in a previous post.  

I did get to show Anna Claire and Jevon, two of our Plantery student apprentices how mowing is accomplished.  For clearing the vegetation, I was inspired last year from a video Austin Eischeid posted to just raise a push mower on the highest setting and rev it into action.  

Jevon mows!

Anna Claire mows!

Some plants that lay over need to be pulled up to come in contact with the mower blades.

This year is our second mowing of the food prairies, and it went off without a hitch.  It took about 40 minutes to mow 650 square feet, but that includes some down time to refill the mower with gas.  

I prefer to mow when we can because the ground up residue provides a mulch that prevents weed growth for much of the rest of the growing season.  Even late into the fall of 2018 I was able to find ground up grass clippings from the January 2018 mowing.  

The finished product. Notice the nice layer of chopped plant residue. It is amazing to see 3 to 4 feet of biomass reduced to a few inches. The deep green clumps are Carex cherokeensis.

And, we were able to find Narcissus × odorus buds still intact after the cut. Mission accomplished.  

Oh, and here’s a video from last year if you want to see the process. Yes, our students do really mow that fast.

Eragrostis, a Grass I Love

One of the perks about living out in the country is I have a delightful 20 minute drive into town to enjoy the east Texas countryside and keep abreast of the phenology of the local flora. 

It was about this time last year right after moving into our new house that I was driving to work familiarizing myself with my new route when a plant sporting a glimmering haze on the side of the road caught my eye.  When I actually had a chance to stop, I pulled off and identified it as Eragrostis spectabilis, commonly known as purple love grass.  I enjoyed seeing the dew collecting on the panicles and the early morning light imbuing it with an ethereal character that would inevitably evaporate as the day aged.  Most sprigs I saw were single, scraggly flowers that looked like the way a young girl might practice putting her hair up for the first time. 

But, one clump was spectacular!  It was full and lush, bigger than a basketball, and hard to miss in the fresh light of dawn.  Every day I’d drive past it and admire that shimering plant against a shaggy fencerow.

I had to have it.  Since I arrived in Texas in July of 2014, I’ve been hunting for short, groundcover species that will perform well in our area.  Most plants I’ve tried are imports, but here was a species right down the road just waiting to have its potential realized.  Being September, I knew that there was a chance it might not survive as many grasses moved in the fall don’t establish well.  But, with love and care and some horticultural knowledge, there was also a good chance it would live.  

With shovel in car one Saturday morning, I pulled off along the roadside and walked over to meet my new friend that I had been admiring from afar.  The spade slid right through the sandy soil, and a few jabs and levers later the Eragrostis was up with a nice rootball still intact.   Any guilt I had collecting the wild vanished a few weeks later when the mowing crews came along and sheared the roadsides.  

Back home, I found a nice spot for the transplant in the catch-all herb bed of our newly formed kitchen garden.  There, I could check on it every day and water it as needed.  I was thrilled when I saw little discoloration the next few days from it adjusting to being moved.  A few blades turned tan and purple, but overall the plant settled in nicely.  

Even though it had a few bruises and browning after being transplanted from the roadside, this mother plant of Eragrostis has settled in just fine.  You can see the speckled haze of flowers hovering above the foliage.  

I loved going out in the mornings and see my new Poaceae pal wrapped in a crystal veil.  The flower color is not as purple/pink as most of the examples I’ve seen in catalogs or online, which made me question it's identity.  But, the height is right, it has knobby rhizomes, and the flowers match what I can find in dichotomous key photos.  My guess is down south the color is weaker than our northern counterparts as is the case for many other ornamental plants in our sweltering heat.  Or, perhaps this southern ecotype sports inflorescences that are a lighter shade of maroon?  I tried another strain of Eragrostis spectabilis from further east a few years ago whose flowers were more pink in color, but our little trial of plants died.  Perhaps they were in too wet a spot in too wet a summer?  Or, maybe it wasn’t locally adapted yet?  Not sure, but this one I discovered has performed beautifully. 

The typical rosy-colored flowers of Eragrostis spectabilis.  

The clump I found and those that I've propagated have more of a light pink or tawny color in the inflorescence.  

As September wore on, the panicles started to mature.  I collected some seed, and sowed them on a whim.  To my amazement, they started germinating within just a few days!  No stratification or even dry storage required.  For those that need a review from plant propagation, dry storage is the name of the germination delay that some seeds experience to prevent them from germinating too early or on the mother plant.

Once the seedlings got some size to them, I took them to school and had a student pot these few up into a couple trays for our school garden beds.  To my amazement, the disturbance in the pot caused even more to germinate!  It seemed to good to be true.  These little sprigs I brought home and planted into beds here at the house.  As more of the original plant’s inflorescences began to mature, I collected more seed to become the stock for our plantings on campus.  

Winter came with the worry of loosing the original clump, but this spring, I was thrilled to see new shoots emerging on the mother plant.  Being a C4 grass, it was slow to get going, but when the brunt of summer arrived it erupted into growth.  Eventually, I tried my hand at dividing the clump into about 20 propagules, and the majority of these survived.  However, divisions do seem to grow a bit slower than those from seed.  I was also delighted to discover a few offspring popping up around the mother plant.  One even sowed its way into a crack in our pavement.  

Now, a year has passed.  We have hundreds that have been planted around the SFA agriculture building.  And, back home a few that I transplanted carpet the ground in a portion of our herb garden.  I’ve also planted it as the groundcover layer in the beds on the eastern half of the swale I’ve been building through our kitchen garden (more on that in a later post).  What few perennials I plugged around these starts look like ship masts emerging out of a grass fog.  The effect is similar to muhly grass (Muhlenbergia sp.), but the height is shorter.  It would occupy more ground, but I ran out of plants here at the house and have to propagate more.  No worries as it appears I’ll have thousands and thousands of seed in a month and Heaven knows how many seedlings next spring.

En masse this Eragrostis is spectacular, especially when covered with morning dew.  Here, it is planted along the swale that runs through our edible patch.  Next year, I expect more perennials to be established and piercing the floriferous fog.  

I feel proud having moved it—perhaps I could go as far as saying saved it?  And, I feel that joy every time I walk past the clumps.  In the morning, strolling past the wet panicles reminds me of the plant perspiration Christopher Lloyd wrote about in Exotic Planting for Adventurous Gardeners.  And, once the dampness vanishes, the flowers brush against your leg like a friendly feline. 

This ecotype of Eragrostis will become a permanent fixture in our prairie plantings here at the house and on campus.  And, why not?  With a plant named love grass from right down the road that thrives in our climate, what’s not to love?

Echinacea Named Tennessee

Echinacea tennesseensis (Tennessee coneflower) is beginning to bloom in our SFA student garden here in east Texas.  Plants that we started over two years ago as class projects have returned yet again and are flowering their little heads off.

I must admit, when Echinacea tennesseensis first bloomed I was amazed at how floriferous it was!  

It's one of my favorite native wildflowers, but I'm a bit biased, being a native from the great volunteer state.  You can easily identify this member of the aster family apart from the other nine or so species of Echinacea that are native to the US. Their inflorescences face east once mature, and the ray florets ascend to the sun instead of drooping like the petals on most other coneflowers.  This plant embodies such a great metaphor for life.  Start every day gazing at dawn and reaching toward the sky; I can get behind that.  Or, in front of that I should say as this trait does force us to consider where to situate it in gardens.  It must be planted on the eastern flank.  Siting it to the west will cause you to only see the backstage of the inflorescences and leave you unable to enjoy the full performance.  

Can you spy the east-facing Echinacea tennesseensis 'Rocky Top' in this incredible planting at Chanticleer's elevated walkway?  Hint, it's on the right.  Compare these blooms where the ray florets curve upward with the typical Echinacea at the back left of the image whose outer rays droop.  

Of course, it's a bit of a miracle that we still have this delightful perennial with us.  Tennessee coneflower is only found in a few counties in Tennessee, and if heroic stewards hadn't stepped in to save it, our world would be less colorful.  It was discovered in 1878 by Augustin Gattinger, and less than a century later in 1961 its absence in field surveys led some researchers to claim it extinct.  Later in the 60's it was rediscovered; however, survival wasn't guaranteed as the land some populations inhabited was cleared to make way for trailer parks and housing developments.  We have people like the late Dr. Elise Quarterman to thank for advocating for this species's livelihood.  Efforts from her and others helped the plant become listed on the endangered species list, one of the first flora ever.  This attention led to areas where Echinacea tennesseensis occurred being protected, and with enough populations safe, the species was delisted in 2011, certainly a success story for horticulture and humankind's intervention.

The endemism is a peculiar subject.  Why is such a floriferous species isolated to just a few counties in Tennessee?  Sure, humans destroyed a few sites, but it seems that it never had the wide distribution that some of the other Echinacea genera enjoy.  The current hypothesis is that the species arose during the hypsithermal interval, a period of climatic warming and drying that occurred around 5000—8000 years ago.  Drier conditions opened the woodlands of middle Tennessee and allowed the colonization of prairie species like our Echinacea.  When the climate cooled and became more moist, forests began to reclaim the land, and this stress-tolerant species began to decline in numbers.  Walck et al. (2002) state that its narrow endemism is due to several factors—seed-based reproduction; large seeds that aren't animal or wind dispersed; self sterility; intolerance of shading; a lack of seed persistence in the soil, and few individuals making it to adulthood in the wild.  All these characteristics would have limited its dispersal from middle Tennessee.  

The xeric-adapted nature of established plants is quite apparent in the root systems. Earlier this spring I had to move some Echinacea tennesseensis, and I was very surprised to discover massive, deep taproots on plants that were only one year old.  Unearthing knowledge about roots (in a literal and figurative sense!) is always exciting, like discovering buried treasure.  I expected to see more rhizomatous roots like those on Echinacea purpurea (purple coneflower) that I've transplanted much of my life .  The soil had mostly sloughed off one taproot, so I rinsed it to get a better look.  Near the crown it was as thick as a plump carrot!   From there, the chthonic organ divided with depth, but the roots were still stout.  (Yes, most of the transplants survived in case you are wondering.)

I learn so much each time I expose roots.  Here, plump taproots on Echinacea tennesseensis likely help the plant survive stressful times during the year and store resources for the coming bloom.  

A close up of the crown of Echinacea tennesseensis.  The pink tinge in the lower wrapper leaves are hints of colors yet to come.  

I'm already applying this new anatomical knowledge to our propagation culture.  This spring, we currently have over 10 deep-celled propagation trays of Echinacea tennesseensis that my student team has grown.  Seeing the deep taproot was insight to not keep the plants in the trays for too long.  

While it is beautiful to see in the gardens, I hope one day to see this Echinacea named Tennessee in its provincial habitat.  Perhaps at daybreak with their heads basking in the new glow of the day and me basking in the existence of such a great species for our plantings.

Mulch Happens

The other night a phrase in The Holistic Orchard by Michael Phillips stopped me reading mid-paragraph.

"Mulch happens."

I was surprised because I feel like horticulture is moving away from wood mulch with the interest in mixed plantings and covering the ground with plants.  Or, at least with that desire in mind (like here and here) if we all aren't quite on board yet. 

The action of mulching just isn't sustainable.  Depending on dead organic matter to prevent weed growth around perennials in place of living plants is a fallacy that will have to constantly be remedied.  It is Sisyphean task.  Hardwood mulch also doesn't naturally occur, except maybe under a fallen, decaying tree.  As Thomas Rainer says, you won't find mulch circles in the forest. 

So, does mulch really happen as Michael wrote?  To make sure that I'm not taking the quote out of context, here it is in full: "Nature builds soil from the top down: Leaves fall, tree limbs decay, mulch happens.    

In the sense that we are used to seeing hardwood mulch strewn across the landscape, no .  We do have an organic layer present in most soils, but it's not a few inches thick of hardwood.   Instead, it's dominated by a mixture of the abscised and the fallen, the green and the brown, the leaf and the stem.  

Michael wrote that when he mentioned mulch he was not talking about recalcitrant hardwood mulch that takes years to decompose.  Instead, he was discussing ramial wood chips, a type of organic matter that comes from branches and stems that are less lignified and higher in nutrients.   He advocated applying these wood chips in random patches throughout the orchard to feed the soil.  His approach is to chop stuff up and then dump piles of it around his fruit trees. They don't form a solid cover, which encourages grasses and other forbs to grow to create a multiculture.  He stated most fruit trees originated along ecosystem edges.  Introducing rough, slowly decomposing organic matter helps to improve the soil similar to these plants' native habitat.  While I haven't studied the use of these ramial wood chips much but want to learn more, the logic behind their use seems sound.  

What I think is fascinating for these perennial cultures—mixed plantings and the use of ramial wood chips in orchards—both schemas ask the question how can we emulate nature and try to enhance the biological systems already in existence, especially with covering the soil.  In both cases mulch happens, just not the way that we traditionally think about mulch.