Monday, December 28, 2020

Where does the corn go? The answer maize surprise you!


I probably have to apologize for that pun, but I do like sweet corn (which is more accurately called maize, and whose scientific name is Zea mays). It makes for a good snack, and of course I love some of the other foods where maize is a major component, such as corn tortilla.

But it should come as no surprise to people that unlike rice, which directly feeds several billion souls, the vast majority of the maize crop does NOT go into directly feeding people. In fact, when I looked it up, I was surprised to find out that only a very small percentage of whole maize makes it to the table.

The largest use of maize is for feeding animals (around 40%), and right behind it is its use as biofuel (around 30%). Less than 10% of the total crop goes to either food or drink in the USA, and even the majority of that ends up as high fructose corn syrup. Unfortunately, very little of that crop goes to making the sweet juicy snack that I love.

For a detailed and interesting look at how this very important grass species impacts the country, I highly recommend watching the documentary King Corn, which is available in its full length below.

Enjoy and learn!

Sunday, December 27, 2020

Sound the alarm! Miscanthus hoodlums escaping!

There is no doubt that the exotic species Miscanthus sinensis (Chinese silvergrass) is very heavily used in commercial and residential landscaping. I see them everywhere nowadays, from mall parking lots, office lots, to the front yards of suburban homes. Even arboretums like the Frelinghuysen Arboretum  in Morristown,  New Jersey use it extensively due to its beautiful form and flowers. But at least until recently, I have not seen "escaped" specimens that have jumped the fence here in New Jersey and made its way into the wild.

M. sinensis behind Panicum virgatum and Pennisetum sp, and Festuca glauca (Frelinghuysen Arboretum)

This changed when I visited the South Mountain Recreation Complex in Essex County, which featured a huge reservoir surrounded by a paved path. People can walk or run around the lake using this path, and trails peel off from it to go into the deeper woodland hiking paths.

All along the perimeter of this path are planted shrubbery as well as ornamental grasses, and one of the species used was of course M. sinensis. I was able to tell it was this because even though all the grasses had been cut to the ground for the winter, I still spotted some of the distinctive inflorescence spikes of this species lying nearby.

Escaped M. sinensis along side of woods
Imagine my surprise when we left the main path and crossed a hilly outcrop to intersect a hiking path entrance, only to see uncut but dried clumps of M. sinensis growing along the woodland edges! There was one main cluster perhaps 4 meters away from some of the cut ornamentals, but there were also secondary clusters and individuals farther away and enmeshed in the native undergrowth.
Escaped M. sinensis in the undergrowth

Fortunately, unlike some other invasive grasses, rhizome expansion in this species is not as aggressive, but it still is somewhat of a concern that this particular population is showing signs of expansion into the nature trails. Time will only tell if this burgeoning invasion will create significant problems in the future.

Friday, December 18, 2020

How one badass grass thrives at the thermal limits of eukaryotic life

It's not an exaggeration to say grasses as a family have adapted amazingly well to most habitats on earth. But there is at least one species that takes that adaptability to new levels.

Living in the active geothermal areas of Yellowstone National Park takes some major adaptations. It is an extreme and hostile environment with rhizosphere temperatures exceeding 40°C. Many proteins denature above 41°C, and in people a body temperature at 43°C or above normally results in death or at the least serious brain damage and cardio-respiratory collapse.

In such an extreme environment, there are only nine vascular plants that have managed to successfully colonize this habitat. Chief among them are the grasses, which are both the most prevalent and most heat-resistant species in the area. But the award for the most extreme plant goes to Dichanthelium thermale (formerly a subspecies of D. lanuginosum) , which was flourishing in soils with an average of 44° C and a recorded maximum of 57°C! (Stout and Al-Niemi, 2002)

(c) James St. John, Wikipedia
When researchers studied D. thermale, they found that it was even more amazing than they initially thought. This grass species had little problem living at the absolutely mind boggling temperature of 65°C for days on end, and they discovered that this ability was the result of a symbiosis with a new endophytic species of the fungal genus Curvularia (Redman et al, 2002).

Curvularia protuberata was found in the roots, leaves, crowns, and seed coats of D. thermale, and neither the grass nor the endophyte could survive on its own above 38°C. But when endophyte-free grass was inoculated with the fungus, it regained its remarkable thermotolerance.

The researchers surmised that this protection from heat could be the result of several possible mechanisms. One possibility is that the fungal endophyte produces cell wall melanin that may dissipate heat along the hyphae and/or complex with oxygen radicals generated during heat stress. Another possibility is that the endophyte may act as a “biological trigger” that allows the symbiotic D. thermale to activate stress response systems more rapidly and strongly than non-symbiotic plants.

Redman et al, 2002

The symbiosis became even more complex when researchers announced that they had found a third party in the relationship several years later. It turns out that the fungal endophyte was infected with a double stranded RNA virus, and that its ability to confer thermotolerance on D. thermale was dependent on this infection!

Endophyte-free D. thermale that was inoculated with the fungus+virus survived in heated environments, whereas endophyte-free D.thermale  inoculated with the fungus without the virus did not survive in the same environment (Márquez et al, 2007).

Márquez et al, 2007

The unraveling of this complex symbiotic relationship could even have applications in agriculture. When tomato plants were inoculated with the wild-type fungus C. protuberata, their tolerance to heat was improved, albeit only slightly, indicating that the mechanism behind this thermotolerance may be conserved among many different plants.

But this potential novel application in the future would not have been thinkable if it were not for the humble D. thermale in Yellowstone and other geothermal parks. So as we marvel with awe at such an intricate and beautiful example of symbiosis, be sure to also give a respectful nod at this one badass thermotolerant grass and its fungal and viral partners!
Modified from Marin et al (2020), te Velthuis (2014), and J. St, John (Wikipedia)

Literature Cited

Marin, Yasmina & Hernández-Restrepo, Margarita & Crous, Pedro. (2020). Multi-locus phylogeny of the genus Curvularia and description of ten new species. Mycological Progress. 19. 559–588. 10.1007/s11557-020-01576-6.

Márquez LM, Redman RS, Rodriguez RJ, Roossinck MJ. A virus in a fungus in a plant: three-way symbiosis required for thermal tolerance. Science. 2007 Jan 26;315(5811):513-5. doi: 10.1126/science.1136237. Erratum in: Science. 2007 Apr 13;316(5822):201. PMID: 17255511.

Redman RS, Sheehan KB, Stout RG, Rodriguez RJ, Henson JM. Thermotolerance generated by plant/fungal symbiosis. Science. 2002 Nov 22;298(5598):1581. doi: 10.1126/science.1072191. PMID: 12446900.

Stout RG, Al-Niemi TS. Heat-tolerant flowering plants of active geothermal areas in Yellowstone National Park. Ann Bot. 2002 Aug;90(2):259-67. doi: 10.1093/aob/mcf174. PMID: 12197524; PMCID: PMC4240417.

te Velthuis, A.J.W. Common and unique features of viral RNA-dependent polymerases. Cell. Mol. Life Sci. 71, 4403–4420 (2014).

Saturday, December 12, 2020

Winter Beauty: Ornamental Grasses!

Panicum virgatum, Schizachyrium scoparium, Calamagrostis sp, Panicum virgatum 

You can find beauty in the most mundane of surroundings.

Deep Cut Gardens in Middletown, NJ features a gorgeous formal garden, tropical and other interesting plants in greenhouses, and short trails for nature lovers. 

But hidden in plain sight in the main parking lot was something that actually made me gasp.

There between the rows of parking spaces and parked cars stood masses of ornamental grasses, their now-dried stems and leaves rising tall and straight towards the cold November sky. Every single island in the lot was filled with these botanical wonders.

The great thing about it was that these were not the non-native Miscanthus sinensis cultivars that are so beloved nowadays by landscape designers, but mostly native perennial grasses.

The tallest were Panicum virgatum cultivars (switch grass), their erect forms standing like disciplined soldiers ready for battle.

P. virgatum
Between stood reddish-hued Schizachyrium scoparium (little bluestem),  another hold-over from the vast prairies of olden America, plus short groupings of what I took to be an elegant Calamagrostis cultivar.
S. scoparium

And for lovers of Miscanthus sinensis, the park had a huge specimen towering over a small decorative pond just steps away from the entrance.

M. sinensis across the pond from the cattails
I love that there has been this strong shift in the landscaping business towards using ornamental grasses as part of their designs. I mean, with their dynamic forms and dramatic color changes over the course of the seasons, such grasses beat boring shrubbery all the time! ;-)

P. virgatum with dried airy panicles still in place

Sunday, December 6, 2020

Calling all orchid-wannabees: Where are the epiphytic grasses???

I was doing a hike at one of the NJ parks a week or so back when I happened to see a grass that was growing from between the branched fork of a now leafless tree.

The grass looked quite happy and healthy, and a quick look at its base showed some accumulated debris, and perhaps even soil. I can only surmise that it got to its present location via a wind blown seed being deposited in between the trunks.

This of course made me wonder why there didn't seem to be any obligate epiphytic grasses.

Epiphytes are plants that spend part of their lives growing on other plants. They use their host for support but do not depend on them for nutrition or water (unlike parasites), and the main reason for becoming an epiphyte in forested areas is somewhat obvious. By growing high up (perhaps even all the way to the top of the canopy), the plant will have access to light that it would not have growing in the soil. 

But the environment for such adventurous species is not a benign one, with the lack of access to soil nutrients and water being the main reasons why not all plants have evolved to take advantage of this lifestyle. Those that did have a variety of morphological and physiological adaptations that allow them to flourish far above the dark forest floor. For example, some orchids have fat pseudobulbs and tubers where they store water and carbohydrates in anticipation of the periodic times when the environment dries out. Their roots are also highly modified so they are able to hold tightly onto trunks and absorb moisture very rapidly using a sponge-like layer called the velamen.  

Epiphytes. (c) Hans Hillewaert - Wikipedia
Even with all these obstacles, a lot of species have made the leap to an epiphytic lifestyle. Epiphytes are not exactly rare, with about 10% of all vascular plants being epiphytic, and with the majority of cases being in the wet tropics. More than 70% of all orchids for example are epiphytic (Atwood JT, 1986), and so are more than 50% of bromeliads (Zotz, 2013).

The Poaceae number more than 11,000 species, and so when I first tried to find examples of epiphytic grasses, I expected quite a number to be living la vida loca, so to speak, high up above where the lighting is good. Instead, the literature turned up...

...a grand total of ONE (perhaps TWO) species of grasses that have been declared epiphytes!

Tripogon capillatus (c) GBIF, specimen from University of Michigan
Tripogon capillatus grows as epiphytes on the basal parts of tree trunks in humid evergreen forest, and thus has the distinction of being one of that rarest of grasses - an epiphyte! It is part of a group that seems primed for the epiphytic lifestyle. Tripogon is a small genus with only around 50 species, and many of its members prefer to grow on cliffs of moist rocks, wet granitic boulders and rocky slopes, while others can live in xeric to dry habitats (Thoiba and Pradeep, 2020). Some of the species in that genus are even so-called Resurrection plants - able to revive after being completely dried out! 

A second possible grass epiphyte is Axonopus compressus, which was discovered as isolated individuals (n=3) in the lower and middle layers of two trees in Nigeria (Obalum, 2018). But neither species is beholden completely to this tree-living lifestyle. They are instead likely facultative (or accidental) epiphytes, and able to grow in many types of environment. 

So why aren't there more epiphytic grasses? 

Why is a family that is more widespread than any other plant family - one that has members that exist in the coldest, the driest, the hottest, the highest environments - why hasn't it evolved a plethora of tree-living, canopy-dwelling species?

I've been thinking about this, and I think it all boils down to the fact that all grasses are primarily wind-pollinated. It turns out wind pollination is generally uncommon in the wet humid forests where epiphytes are mostly found, and according to at least one source, there have been no reports of any epiphyte that sheds wind-borne pollen (Lowman and Rinker, 2004).

But who really knows? Perhaps there is some other explanation(s) as to why what many consider the most ecologically successful plant family in the world cannot seem to also conquer the tree canopies. 

Literature Cited


Lowman, M.D. & Rinker, H. Bruce. (2004). Forest Canopies: Second Edition. 

Obalum, Sunday (2018). Diversity and spatial distribution of epiphytic flora associated with four tree species of partially disturbed ecosystem in tropical rainforest zone. Agro-Science v17: 46-53

Thoiba, K  and Pradeep, AK (). A revision of Tripogon (Poaceae: Chloridoideae) in India. Rheedea - Journal of the Indian Association for Angiosperm Taxonomy. Vol. 30(2): 270–277
Zotz, Gerhard (2013). The systematic distribution of vascular epiphytes – a critical update. Botanical Journal of the Linnean Society 171(3):453-481