Sunday, August 14, 2022

Uncovering the lair of the sand centipede

I love my wife, but whenever I hike with her my botanizing is reduced to a minimal level.

So when I got the chance to explore a nearby trail on my own, I jumped at the opportunity and took my Nikon 3400 DSLR and  macro lens with me.

The beginning portion of the trail featured a wide sandy path, and on a previous excursion I had noticed really interesting critters that seemed to be slithering under the sand.

The trail covered with "sand centipedes"

It was the usual hot and humid Florida summer day, but this time I literally knelt to observe the little critters. The ground was really hot, but I was entranced by what I saw.

The long bodies of this grass formed sinuous patterns, the leaves half submerged in the sand and looking like the segmented legs of a centipede. I had to be careful not to keep stepping on one, although I knew that they were tough hombres that could take a few adversities and keep on ticking.

A half buried sand centipede as it crawls along the burning ground

Amazingly enough, many of them were in bloom or past bloom, and multitudes of flower and seedheads rose from the ground like the compound eyes of arthropods. They really did look like segmented critters!

Like a stomatopod with 2 eyes peering up from the sand

I identified the species as Eremochloa ophiuroides, which is a turf grass here in the southeast USA. It was introduced to the country in 1916 from China, and these specimens must have "escaped" from nearby lawns. Its common name in the area is "centipedegrass", which either refers to the overall body form or the segmented appearance of the inflorescence.

Inflorescence and stoloniferous culm that had been half buried in the sand

The species looks superficially like Stenotaphrum secundatum (which is called St. Augustine Grass here), but it is smaller and the inflorescence looks quite different.

Interestingly enough, I saw an ant going up and down the flowerheads, and I photographed what looked like aphids perched at the base of the rows of spikelets. The ant seemed to be attracted to the lumpish specks, and I was reminded of some recent research that hypothesized that  Eophiuroides might be pollinated by various insects (Joseph et al, 2020).

Ant cultivating aphids on the inflorescence?

The spikelets themselves were quite small, but the silvery stigma and purple anthers were cute, and I spent some time getting macro shots of the structures. 

Purple anthers and silvery stigmas

I must have spent an hour or more in the heat and sun examining this population of "sand centipedes". I love tiny critters, and the small size of this species was quite attractive. True, it might only be a common turfgrass to some, but the exotic location that I found them in and the fact that they were in bloom captivated the explorer in me. Beauty lies all around us, even in the most common of things.  You just need to open your mind's eye and see.

Literature Cited

V Joseph S, Harris-Shultz K, Jespersen D. Evidence of Pollinators Foraging on Centipedegrass Inflorescences. Insects. 2020 Nov 13;11(11):795. doi: 10.3390/insects11110795. PMID: 33202733; PMCID: PMC7696019.


Thursday, August 11, 2022

Life without Animal Pollinators: Why Grasses Embraced the Wind

Phalaris arundinacea grass inflorescence with white anthers and stigmas and foraging hoverfly.

Some people might be surprised to discover that grasses are flowering plants. That's because when they are compared to the large flowering structures sported by some other angiosperms such as orchids, grass flowers are miniscule indeed. They are not as large and showy as the flowers in some other plants because they are specialized for wind pollination, and thus have no colorful sepals or petals.

This reliance on wind for pollination is called anemophily, and it is in contrast with pollination via insects (entomophily) or vertebrates (zoophily). Around 10-12% of flowering plants are wind-pollinated (Ackerman, 2000), and such plants seem to have evolved specific traits that together make up a "wind pollination syndrome".

Imperata cylindrica inflorescence with purple anthers

Some of the traits in this syndrome are those which grasses exemplify, and include:

  1. Having many pollen grains compared to animal-pollinated plants
  2. Pollen grains are usually unornamented
  3. Having many flowers compared to animal-pollinated plants
  4. Petals are usually small or absent
  5. Nectaries are absent.
  6. Flowers are unscented
  7. Styles and stigma are feathery.
  8. Anthers with the pollen tend to have long filaments and are held away from the leafy structures to aid in wind dispersal
  9. Plants tend to occur in open habitats where wind is plentiful.
Panicum virgatum inflorescence with reddish-brown anthers and pink stigmas

On first look, people might think that wind-pollination is less effective and more "primitive" than pollination by insects and other animals. Indeed, Charles Darwin himself expressed surprise that any plant should display this type of pollination, given how "wasteful" it seemed to him (Darwin, 1876).

But amazingly enough, not only is wind pollination the derived condition (that is, plants started out as being animal-pollinated, but then evolved wind pollination), but studies have shown that anemophily is about as effective as animal pollination when it comes to the percent of pollen that manages to be captured by receptive stigmas! (Harder, 2000).

Andropogon gerardii inflorescence with yellow anthers and purple stigmas

The impetus for the evolution of wind pollination in plants that used to have animals as pollinators has been hypothesized to be situations where animal pollinators become unreliable. For example, some areas that are newly-colonized by a plant may have scarce or absent animal pollinators. In this case, this "pollen limitation" can result in the evolution of wind pollination in the species. Preliminary studies have supported this notion and have shown that pollen limitation is less of a problem in wind pollinated plants than in animal pollinated ones (Friedman and Barrett, 2009).

Paspalum notatum inflorescence with blackish purple stigmas and anthers

In the case of grasses, the very attributes that partly define the family - high density populations that dominate and saturate the environment - may necessitate the use of wind for pollination.  The lack of enough animal pollinators to assure reproduction in these relatively dense populations have pushed the Poaceae to use wind as the primary mechanism for the dispersal of their pollen.

So the next time you get an allergy due to pollen, don't blame the plants. Blame the lack of animal pollinators! ;-)

Cenchrus spp inflorescence with yellow-orange anthers and purple stigmas

References

Ackerman JD. Abiotic pollen and pollination: ecological, functional, and evolutionary perspectives. Plant Systematics and Evolution. 2000;222:167–185.

Darwin C. The effects of cross and self fertilisation in the vegetable kingdom. 2nd edn. London: John Murray; 1876.  

Friedman, J., & Barrett, S. C. (2009). Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants. Annals of botany, 103(9), 1515–1527. https://doi.org/10.1093/aob/mcp035

Harder LD. Pollen dispersal and the floral diversity of monocotyledons. In: Wilson KL, Morrison DA, editors. Monocots. Melbourne, Australia: CSIRO; 2000. pp. 243–257.

Thursday, August 4, 2022

The Many Faces of the Inflorescence of Bahia Grass (Paspalum notatum)


Paspalum notatum (aka Bahiagrass) is one of the species used as a perennial turfgrass here in the southeastern USA. It is also a forage grass, and is native to the southern parts of the American continent.

I was walking to the gym last week when I noticed that a lot of the wild grasses along the sides of homes under construction had the very distinctive inflorescence of this species rising up from the ground like little black penants. 

The two spike-like racemes of P. notatum bifurcate from a common point to form the rather attractive digitate flowerhead and seedhead. Each spikelet has two florets in it, one being fertile and the other sterile. 

The immature flowerhead is all green it seems, and as it develops you start seeing the black purple anthers and feathery stigmas (looking like the usual purple caterpillars) coming out of the spikelets.

P. notatum reproduction depends on the ploidy level of the individual plant. Those that are tetraploid (four sets of each chromosome)  are normally apomictic, with unfertilized but viable seeds being produced, while those that are diploid (two sets of chromosomes) are wind-pollinated and cross-pollinate. Seed production is high, and the species is highly successful in its distribution.

After fertilization, the spikelets seem to become darker colored, and after awhile dry out as light brown seeds, which are ready to be dispersed. 

I must admit, I really like this grass. Its flowerheads are distinctive and cute, and as a turfgrass it does not look as coarse and rough as Stenotaphrum secundatum (St.Augustine Grass), which is the other type of grass in our community.

Tuesday, July 26, 2022

Sandburs aren't 'Evil'

I was observing some of the grasses in Sandy Hook Beach, NJ last week, when I chanced upon some weird looking seedheads in the sand. They looked like round pods, but with sharp thorn-like protrusions decorating the surface.

I had briefly encountered this species before, but now I took some time to photograph it. Unfortunately, I did not have my macro lens with me, but the structures were large enough that I could get good enough pics.

Cenchrus longispinus is an annual whose spikelets are enclosed in tough, spiny burrs. These burrs can float, and dispersal by water is one way the grass spreads its seeds. The barbs that sprout out from the shell also aid in dispersal, as they can latch onto passing animals or the clothes and shoes of people. Unfortunately, the sharp spines are also quite capable of piercing human skin, and I can only imagine what it would be like to be walking on a sandy beach and suddenly step on a bunch of these well-protected propagules.

Indeed, a quick read of some of the articles on this grass will tell you just how much people loathe it. The word "evil" in particular is used a lot when describing sandburs, which is rather undeserved given that the definition of the term is that it is "profoundly immoral and wicked". In my opinion, this is something which should never be ascribed to animals or plants that are simply doing what they do to survive. There is likely no conscious desire on the grass to hurt people, or even to inconvenience or bother anyone. To it, we are simply nothing more than transportation for its progeny, and it neither wishes us harm nor well-being ;-)


Saturday, July 23, 2022

How many blades of grass in the world?


 Note: I welcome corrections to my calculations. Math was not exactly my best subject!

How many blades of grass in the world?

This is a question sometimes asked by people, and one which seldom gets any answer.

In fact, it's near impossible to resolve this question, with one major factor being that different species of grasses can attain different final maximum densities.

However, it is fun to calculate the number of blades of grass for narrower and more limited scenarios.

For example, would it be possible to calculate the total number of blades worldwide for a single species?

In this case, we would need to know 2 things: The density per given square area of that species, and the total area covered by the grass worldwide.

Only a few grass species have had their total coverage area estimated by researchers, and one of those is the aggressive Imperata cylindrica (cogon grass). There are some estimates that this species may cover as much as 500 million hectares worldwide, although the veracity of this staggering number is open to question.

Nevertheless, if we take this number as a given, and add in potential densities of cogon grass blades (0.25 per square cm or 2500 blades per sqm), then we quickly get really large numbers.

Since there are 10,000 sqm per hectare, then 1 hectare of cogon grass can have around 25 million blades of the grass. Multiply this by 500 million hectares and you get the absolutely huge number: 1.25 x 1016 blades of cogon grass in the world!

In order to put that number in perspective, if we take the current human population of the world at 7 billion people, then there would be almost 2 million blades of cogon grass for every single person.

Or to put it another way: if you lined up each cogon grass blade every meter in a straight line, you would get a line of plants that stretched 12.5 trillion km, or an absolutely mind boggling 1.3 light years! The distance from the sun to Pluto is only 5.9 billion km, so you could potentially have more than 2100 lines of cogon grass blades stretching from the sun to Pluto!

Imperata cylindrica (cogon grass) in flower

Now we can take it even one step farther, and examine a "fictional" situation.

How many blades of grass would there be if a species of grass covered all the land area in the world?

The winter annual invasive Taeniatherum caput-medusae (medusahead grass) has been seen to have as many as 21,500 plants per square meter, which comes to around 21.5 billion plants per square km. Since total land area of the world is approximately 130 million square km, then if this species covered the entire earth, then we would be talking about 2.795x1018 plants

To put this number in perspective, this would be about 400 million medusahead plants for every person in the world

Or to put it another way: if you lined up each medusahead grass every meter in a straight line, you would get a line of individuals that stretched 2.795e+15 km, or an absolutely mind boggling 288 light years! The distance to the nearest star Alpha Centauri is only less than 5 light years.

Taeniatherum caput-medusae (medusahead grass)
Such amazing numbers mean that grasses are likely the most populous meter-scale organisms on the planet today!

References

Sharp, Lee A.; Hironaka, M.; Tisdale, E. W. 1957. Viability of medusa-head (Elymus caput-medusae L.) seed collected in Idaho. Journal of Range Management. 10: 123-126. [2118]

Torell, Paul J. 1967. Dowpon--an aid to reseeding medusahead-infested rangeland. Down to Earth. 23: 6-8. [6005]

Sunday, July 17, 2022

Now, THAT'S a front yard!

Google Street View in May 2022

We were on our way to a hiking location here in North New Jersey, and  on the way we passed by some fairly upscale communities. Most had wide front lawns, the grasses kept immaculately low to the ground, with occasional homes sporting large ornamental grasses like Miscanthus sinensis and Calamagrostis cultivars.

But suddenly, I gasped and pointed at something to my fellow passengers in the car. One of the houses had a front yard that was absolutely wild. Lots of tall stately grasses waved in the wind, and there were so many of the tall grasses and shrubs and forbs that the house itself was almost obscured from view.

Unfortunately, we did not have time to stop, but I made a quick mental note of some landmarks around us. When I got home later, I used google street view to try to find the home again, although I was thinking it was a long shot. But amazingly enough, the house front yard was so distinctive I actually did manage to locate it! 

The google street view image was from spring of this year, so the plants were not as high as they are now, and thus not as majestic. But there was no doubt that I had found the right house.

I thought it was charming and daring of this homeowner to go against the grain by not using the usual turf grasses, and I liked the overall effect. But one of my passengers had exclaimed "It's like a jungle!" 

Oh well, you can't please everyone!

UPDATE (2022-07-23)

I managed to take a pic of the front lawn as it looks now, and it looks great. Sorry for the quality of the photo, but I was just using my smartphone at the time. Love the masses of Calamagrostis!


Friday, July 8, 2022

Ornamental Grass Hunting at the Big Box Stores (and Where Big Box Grasses Go to Die)

Leymus arenarius spikelets (taken using non-macro lens)

I am a big fan of ornamental grasses. 

In my time I have purchased many natives such as various Panicum virgatum cultivars ("Northwind",  "Thundercloud", "Heavy Metal", "Hot Rod"), Andropogon gerardii cultivars ("Black Hawk", "RainDance"), and even a few Schizachyrium scoparium like “Twilight Zone”. I even have potential invasives like Miscanthus sinensis "Morning Light" and Japanese Blood Grass (Imperata cylindrica), both of which I obtained a long time back before I knew they were considered iffy ornamentals.

Most of my purchases have been at specialized Garden Centers or from online, but every time I visit Lowe's or Home Depot, I make it a point to visit their Garden department in search of unusual grasses.

The typical store scatters the grasses across various sections, but Lowe's is a favorite of mine because some Lowe's stores even have an ornamental grass section!

You go, Lowe's!

On one trip to a New Jersey Lowe's I decided to list all the available ornamental grasses in the store. 

Most of the ornamental grasses were crowded into one bench, but there were still a few scattered here and there. The usual purple fountain grasses were available (Cenchrus setaceus/Pennisetum setaceum), as were varieties of Miscanthus sinensis ("Adagio", "Variegata"), and the really cute Festuca glauca (in this case, "Beyond Blue"). There were even pots of Cymbopogon citratus (Lemon grass), which normally is placed separately from other ornamentals. These are typical types for this region, as well as in Florida stores (especially the fountain grasses).

Interestingly enough, I did find a species that I normally don't see in New Jersey stores. A couple of pots had Cortaderia selloana (White Pampas Grass)!

An unusual Cortaderia selloana for sale

This species of course has been considered invasive for some time now, but it would be wrong to say it is not gorgeous when in full flower, and so it has been a favorite of lay gardeners in many places. I was surprised to see it here though, as  it usually grows better farther south.

But the species that really stopped me in my tracks was a row of Leymus arenarius. The grasses were in flower, and the blue green hue of the leaves of this native species made me love it on sight. It's safe to say that I will likely get this sand-loving grass in future if I have space for it in my new home.

Leymus arenarius - beautiful in blue

On the way back to my car, I saw some clearance racks that had been parked to the side of the store. Curious about what I would find, I walked closer and found myself staring at the dying and drying bodies of various potted grass specimens. 

Where box store grasses go to die

Most of the dried up plants had grown long, their limp blades obscuring the name tags. I peered closely and found that many of them were Calamagrostis spp, with a couple of Miscanthus sinensis cultivars thrown in and a lone Muhlenbergia sp. A few still had green blades poking up through the mass of dried gold, and I knew that these could still be saved.

When I asked some store reps about the items, they said those plants were going be thrown away if no one bought them at clearance. It seems too many were in stock, and most had deteriorated due to negligence and poor lighting. 

I left after awhile, feeling a bit sad for the dying grasses. There should be a way to calculate the correct stock, and a way to take better care of these ornamental plants.


Saturday, July 2, 2022

Top of the World, Ma!


I visited Olympic National Park in Washington State last year, and the subalpine meadows on its tall peaks drew us in. The open tree-less spaces, the snow-covered mountain heights in the distance, the ground hugging grasses and forbs. I would not trade this vast panorama for any of the closed humid spaces down below.

This is a place where your soul can soar.

Thursday, June 30, 2022

At My Signal, Unleash Hell: How Invasive Annual Grasses Use Pestilence Against Their Native Perennial Rivals

Taeniatherum caput-medusae (Medusahead Grass) Inflorescence

In previous posts, I touched upon some of the ways invasive grasses manage to overwhelm native populations. 

Usually, this involves having some direct competitive advantage over their rivals. This may include pathogen release (they leave behind all the pathogens that afflict them back in their own native land), some intrinsic competitive abilities, or through some life cycle advantages (for example, as in the diagram below, the ability of Taeniatherum caput-medusae or Medusahead Grass to create flammable litter that prevents competitor germination and clears the rest via frequent wildfires).

How T. caput-medusae (Medusahead Grass) dominates its competitors

Amazingly, however, a new way that invasive annual grasses manage to dominate their perennial native rivals has been discovered. In California, more than 9 million ha of land have been invaded by European winter annual grasses like Avena fatua (Wild Oats), which have usurped the native perennial bunchgrasses. Vast fields of these invasives have paradoxically enough, created the so-called "Golden Hills of California", which have become iconic to that region.

Golden Hills of California

The ability of these invaders to dominate the landscape was thought to be through direct competition with native perennial bunchgrasses, such as Nassella (Stipa) pulchra and Elymus glaucus. But some studies showed that the exotics were in fact poor direct competitors, and other factors were needed to explain their dominance. 

Avena fatua, an exotic and invasive annual grass in California

One of these factors turned out to be a virus!

The barley and cereal yellow dwarf viruses (B/CYDVs) are a family of viruses that are generalized pathogens of grasses, and can cause stunting and slow growth. They travel from host to host via intermediate vectors, which are various species of aphids. The aphids take in the virus from an infected plant when they suck on the phloem, and then transfer it to another plant when they move to new pastures.

Aphids on spikelets of T. caput-medusae (Medusahead Grass)

The invasive grasses compete against their perennial grass rivals by amplifying the population of the aphids, and this in turn significantly increases the pool of infectious viruses. Researchers found that aphids not only were much more attracted to the exotic annual grasses, but that their fecundity increased significantly in the presence of these species. Aphid densities were up to 800 times greater in areas with dense stands of the invasive annual A. fatua, and the infection rate of native grasses with B/CYDV more than doubled! The negative effect of this pathogen on perennial bunchgrasses is more severe than on the short-lived annuals, and this difference is enough to tip the scales of the competition.

By unleashing the viral pathogens against their more vulnerable perennial rivals, A. fatua and other exotic annual grasses have managed to dominate the California landscape. This unusual type of competition (called "apparent competition"), seems to also be available to other exotic annual grasses such as T. caput-medusae, which typically dominate their own areas through more direct methods.

Golden Medusahead Grass carpeting the ground in Oregon

References:

Borer ET, Adams VT, Engler GA, Adams AL, Schumann CB, Seabloom EW. Aphid fecundity and grassland invasion: invader life history is the key. Ecol Appl. 2009 Jul;19(5):1187-96. doi: 10.1890/08-1205.1. PMID: 19688926.

Malmstrom, C.M., McCullough, A.J., Johnson, H.A. et al. Invasive annual grasses indirectly increase virus incidence in California native perennial bunchgrasses. Oecologia 145, 153–164 (2005). https://doi.org/10.1007/s00442-005-0099-z


Sunday, June 26, 2022

The Tree and the Reed: How Wind Affects Grasses


Video above shows Phalaris arundinacea (Reed Canary Grass) being buffeted by wind.

There are many versions of Aesop Fable's The Tree and The Reed, a tale which first appeared in Ancient Greece, and whose moral about pride and humility still resonates to this day. One of the versions goes thus:

A Giant Oak stood near a brook in which grew some slender Reeds. When the wind blew, the great Oak stood proudly upright with its hundred arms uplifted to the sky. But the Reeds bowed low in the wind and sang a sad and mournful song.

“You have reason to complain,” said the Oak. “The slightest breeze that ruffles the surface of the water makes you bow your heads, while I, the mighty Oak, stand upright and firm before the howling tempest.”

“Do not worry about us,” replied the Reeds. “The winds do not harm us. We bow before them and so we do not break. You, in all your pride and strength, have so far resisted their blows. But the end is coming.”

As the Reeds spoke a great hurricane rushed out of the north. The Oak stood proudly and fought against the storm, while the yielding Reeds bowed low. The wind redoubled in fury, and all at once the great tree fell, torn up by the roots, and lay among the pitying Reeds.

The reeds mentioned in these tales were probably a hodge-podge of riverside-living graminoids. The original and most likely species that answers to this name is Phragmites australis (Common Reed), but the term may also refer to other grasses, such as Phalaris arundinacea (Reed Canary Grass), Arundo donaxNeyraudia reynaudiana (Burma Reed), various species of Calamagrostis, as well as a few other assorted members of the Poales. All these plants are herbaceous, with thin leaves that seem to support the central idea of the fable about wind resistance, but the reality is actually more complex. 

It is true that grasses are able to withstand gusts that would topple large trees, but they too can be negatively impacted by continuous strong winds, either due to shaking (seismorphogenic) or rubbing (thigmorphogenic) processes.

Some of the effects of wind include:

  • Increased leaf transpiration, which means grasses lose moisture faster through their stomata. 
  • Decreased leaf extension, which means the grasses produce less leaves.
  • Slower growth rate.
  • Damage to leaf surfaces, including displacement and smoothing of the epicuticular waxes, damage to the cuticle, collapse of epidermal cells and fracture of trichomes.

These effects increase with increasing wind speed, and older leaves are disproportionately affected.

In addition, studies of wind effects on wheat showed that there was significant reductions in grain yield when the grasses were exposed to strong continuous wind. There were less heads per sqm, less kernels per head, and each kernel weighed less than normal. All these negative effects show that Aesop's Fables was not exactly right when it marveled at the invincibility of reeds compared to the more arrogant trees during a storm. 

As an aside, I love seeing grasses swaying and dancing in the wind, especially when they occur in large masses. This is why I decorate my home with lots of ornamental grasses; their movement gives a very attractive active component to the home compared to static bushes and trees. But now that I know the effect of wind on these plants, I'm more careful about wishing for the stronger and damaging winds.



References

Pitcairn, C.E.R., C.E. Jeffree, and J. Grace. 1986. Influence of polishing and abrasion on diffusive conductance of leaf surface of Festuca arundinaceae Schreb. Plant, Cell and Environment 9:191-196.

Russell, G., and J. Grace. 1978. The effect of wind on grasses. V. Leaf extension, diffusive conductance, and photosynthesis in the wind tunnel. Journal of Experimental Botany 29:1249-1258.

Smika, D.E., and R.W. Shawcroft. 1980. Preliminary study using a wind tunnel to determine the effect of hot wind on a wheat crop. Field Crops Research 3:129-135.


Friday, June 10, 2022

Goodbye to an Old Forest Friend


I have mentioned how we like hiking, and more times than not we tend to hike in heavily shaded areas like closed canopy forests. This is mostly because my wife is not usually a fan of walking under the full sun. 

In such places, grasses are not the major component of the understory. They tend to occur in small patches or even in single tufts in the dimly lit ground. Where they tend to occur in masses, the species are usually shade-tolerant aggressive invaders like Microstegium vimineum (Japanese stiltgrass) or Oplismenus undulatifolius (Wavyleaf basketgrass).

But one of the more numerous of the grasses that thrive in the shade is one that I personally find attractive. Dichanthelium clandestinum and its ilk have broad dark green leaves and a habit that you can't help but love.

Beautiful broad and dark green leaves
I encounter it relatively frequently here in the Northeast, and I have stumbled upon it once or twice in Florida.

I also see specimens of this grass close to my home in New Jersey whenever I go for my afternoon walk. They sit alongside the paved path around a nearby lake, and I make it a point to always stop and marvel at the beautiful forms that grace the lakeside and the nearby wooded area.

These are such distinctive critters, and interestingly enough, I see them not only in deep shade, but in brightly-lit areas as well, a testament to the adaptability of this grass.

Spikelets and florets in June
This species also has a somewhat unusual flowering scheme, as I mentioned awhile back in another post. During early summer it produces "normal" flowers which are pollinated when open ("chasmogamous"). Then later in the season, the same individual has closed flowers hidden in the sheaths that will be self-pollinated ("cleistogamous").

Spikelets and florets (macro view) in June

I think this will be my last season in this home, so it saddens me that this will also be the last time I see the D. clandestinum that make their living around the lake. They have been my yearly companions in my jaunts under the shade, and I wish them well. Perhaps someday when I come to visit, I will again walk around the lake path, and say hello to these old friends.

Tuesday, May 31, 2022

Say this 5 times fast: Stenotaphrum secundatum!


 A lawn in a lawn right?

But interestingly enough, the species of grass used to create lawns varies widely as one goes from one region to another in the USA.

In our home in New Jersey, our really old lawn (which I inherited from previous owners) is a mishmash of cool season grasses like Poa pratensis (Kentucky blue grass), Fescue spp, and Lolium spp (eg. Perennial Ryegrass). 

By Kevin Thiele from Perth, Australia

In Florida however, we were confronted by completely different species, those more adapted to the warmer weather all year round. In our case, a rhizomatous and stoloniferous grass called Stenotaphrum secundatum, which has the local name St. Augustine grass (and various other common names around the world).

From a distance, the major difference is probably the lighter color of the lawn. But when you actually look closely the change in habit is very obvious. S. secundatum is a creeper - its stolons or aboveground horizontal stems allowing it to "crawl" along the ground like some green hued centipede. This behavior is quite unlike its cool season brethren in the north, which at best have underground rhizomes. 

I was so taken by this creeping behavior that I potted one, set it down on our lanai, and attempted for a short while to see how far it would stretch along the cement floor in its search for soil. It grew by around 5 cm in 12 days before I had to stop the experiment due to eternal circumstances, but I may repeat the experiment again later.  

Potted grass as it crawls out of the pot and starts to search for soil

The composition of the lawn also affects how it is viewed even from far away sometimes. For example, in the image below, the lighter green areas are S. secundatum, while the dark lot is likely Paspalum notatum (Bahia grass). The border between the two species was amazingly straight most times, although S. secundatum seems to have the more pronounced tendency to encroach onto the other territory. In addition, I noticed various other plant species (aka weeds in lawn parlance, haha) had a harder time establishing themselves in the dense masses of culms and blades and stolons that S. secundatum creates. 

Lawns from high up

A third type of turf grass in the community is a very small, fine leaved species used for the golf areas, and the next time I'm there I'll be sure to take a sample and try to ID it. I know some people are quite ambivalent (or even hostile) towards turf grass, but after being in an HOA community that uses various species to populate the landscape, I have started to become quite interested in the ecology of lawn grasses.

More to come on this perhaps.


Sunday, May 22, 2022

Let Them Grow Cake! Climate Change and The Wheat Crises

by Bluemoose
Triticum  aestivum (common wheat) and a few other species in the grass genus Triticum  (T. durum and T. compactum) are the source of one of the most important staple foods in the world. These grasses are grown in more than 200 million ha of land worldwide, and in 2020 world annual production of wheat stood at 760 million tons. But now an unfortunate combination of climate change and war have threatened our food supply.

Extreme weather events in almost all the wheat producing regions in the world have been causing chaos in the food supply. India, one of the top three wheat exporting countries,  has seen record high temperatures that have severely impacted their crops, so much so that the Indian government just declared limits on wheat export. In China, floods have also potentially compromised wheat supply, and in the EU, US, and Canada various combinations of drought and unseasonably warm temperatures have also threatened wheat crops. Meanwhile, Russia seems relatively unaffected by the extreme weather events going on elsewhere, but the war in Ukraine has limited its role in at least helping to dampen the growing impact of climate change on this year's food supply. Some estimates have declared that the world has only 10 weeks supply of wheat left, and this will be sure to create increases in the prices of bread and other staple foods going forward.

In the end, we owe it to ourselves and to our children to makes sure we address the growing impact of climate change, not only on other species, but on our own, before it becomes too late. 

Monday, May 16, 2022

A Himalayan Miracle: The Terai-Duar Grasslands of India, Nepal, and Bhutan

One-horned Rhino Hiding in the Grass (From Outlook India, by Narendra Bisht)

At the foot of the Himalayan mountain ranges lies a narrow band of grasslands and savannas that is only 25 km wide, but features some of the tallest (non-bamboo) grasses in the world, and are a host to the most amazing animals.

The Terai Grasslands (By Terpsichores and Tom Patterson, US National Park Service)

Not only is this area home to the rare one-horned rhinoceros (Rhinoceros unicornis), but it also boasts a multitude of ungulates (deer and their ilk), as well as the Asian Elephant (Elephas maximus) and the Bengal Tiger (Panthera tigris)!

Elephant (By Yathin S Krishnappa)

I first heard about these grasslands from a nature documentary about biomes (Earth 2: Grasslands, with David Attenborough), which briefly showed gargantuan Asian elephants, who were themselves dwarfed by tall grasses that almost hid them from sight. The area was not named, but I was curious about it. Through the miracle of google I finally managed to pinpoint the location as the Terai-Duar grasslands, which spans three countries (India, Nepal, and Bhutan), and is maintained by annual flooding during the monsoon season, and not only by fire or grazing. 

The grasses that serve as the foundation of this system include Saccharum spontaneum (called kans grass and talahib where I grew up), which can grow up to 4 meters tall and more. Another equally tall grass in the place is Cenchrus purpureus, which appropriately enough is sometimes called elephant grass (but which is called Napier grass most times, and which I encountered in southern Florida). The terai also has stands dominated by the much shorter Imperata cylindrica, the same cogon grass that dominates in many other regions of the world. I found it interesting that many tourist and even nature sites kept calling them the tallest grasses in the world, even though bamboos of course can get much much taller.

Cenchrus purpureus dwarfing even a school bus in Florida City

I once mentioned I get really nervous about being alone in a shaded closed canopy forest, where my over active imagination always thinks there is some predator lurking in wait behind the next tree trunk. But being submerged in these tall grasses must be equally scary, something that Stephen King explored in his novelette In the Tall Grass. In this case, the fact that the Terai grasslands are home to the Bengal Tiger probably has something to do with my anxiety.

Bengal Tiger in the Grass (by PM Dhakate)

Nevertheless, the Terai grasslands are firmly in my bucket list of places to visit. But like many old growth grasslands, most of the Terai has been converted to agricultural and other human uses, mainly due to its rich soil. In fact, the region is one of the most endangered in the world. Fortunately, there are some major parks that seek to protect the grasslands, including Shuklaphanta National ParkChitwan National Park, and Bardia National Park in Nepal, and Dudhwa National Park in India.

Be sure to visit and be amazed by this fantastic place the next time you are in that area!