A meeting of giants

Flowerhead of C, purpureus

I admit I am not your typical tourist. Sometimes I like to wander the streets of cities I visit, just looking at all the flora and fauna to be seen. This was the case when I visited Florida City in Florida, which is close to Everglades National Park and Key Largo.

I was walking along the sidewalk of a busy street in this smallish city (ok, it was Route 1, a state highway!), when I had to do a double take. Along a dead-end side street next to one of the many motels in that area was a long row of gigantic grasses! 

Long row of gigantic grasses

They were tightly packed and stretched in an unending row from the start of the street (SE 1st Ave) to its end near the motel back. The grasses rose to 4 meters in height or more, and above some were whitish flowerheads.

Schoolbus parked next to C. purpureus for scale. 

My first thought was that I stumbled on Arundo donax, but a quick inspection of the flowerhead nailed the species as Cenchrus purpureus (syn. Pennissetum purpureum), which has various common names such as Napier grass, elephant grass, and Uganda grass.

Young C. purpureus spreading across a recently fallow lot

The grass had spread from the row to infest a field of trees behind it. The land looked abandoned, but a quick look at Google Street View from previous years showed that it had once been carefully tended, with palms planted in neat rows. Now young Napier grass sprouted from all over the field, and I was thinking that without tending that the lot would soon be filled with it. I also encountered another large stand of Napier grass east of the motels, along with smaller clusters that must have been derived from the larger stands (see image below).

C. purpureus in yellow, N. reynaudiana in red.

Interestingly enough, I spotted other large grass stands in the distance in the empty lot, but a quick look showed that they were a different species!

I trudged into the lot and found out that the new grasses were Neyraudia reynaudiana (Burmareed), their gigantic forms topped by huge plumes of brownish flowerheads. They were scattered in small clusters, and the nearest group was about 30 meters away from the equally tall Napier grass.

Neyraudia reynaudiana

I wondered what would happen when the two species finally met in that empty lot. Would one species be dominant over the other, or would they coexist, the two groups forming a field of gigantic grasses with distinctly different flowerheads? Which grass would prevail in this clash of giants?

Another interesting thing is that I have seen both species all over Southern Florida, but they both become much rarer as one travels north. I have not seen Burmareed in Lake Okeechobee (though I have seen what I took to be Phragmites australis in the distance next to the lake), while Napier grass was quite abundant on the northern lake shore. However, once one gets closer to Orlando, the glimpses of giant grasses becomes rare to non-existent, and I have only seen one cluster of Napier grass in the Orlando area. The specimens were located in Shingle Creek Regional Park, and they seemed a bit unhealthy looking.

N. reynaudiana on the road to Everglades National Park

It is a change to the landscape that is quite evident, perhaps even to the eyes of laymen. The land of giant grasses transforms into a land filled with Andropogon sp. and Aristida sp., much smaller grass species that nevertheless dominate many areas in a way that even the giants might envy.

Spider lurking in a C. purpureus inflorescence

From googly to reality

The reality

In a previous post I talked about the use of Google Street View and how it can allow one to view the spread of invasive species over time. 

The Googly (from Google Street View)

The example I used was for Neyraudia reynaudiana (burmareed), a tall fire-adapted grass which has been destroying Pine Rockland ecosystems in Florida.

I swear that I was not looking specifically for it, but I somehow ended up in the same place during an exploration in Homestead, FL. In fact, I did not realize it was the same place until I came back to the hotel and mapped the location on Google Maps, where I was extremely surprised to discover the coincidence.

The masses of N. reynaudiana was heaps more impressive in person, their huge 3-4 meter tall forms towering above me like some impenetrable wall, and I stood there for so long that some local started eying me suspiciously as I wondered at the stately grass. Perhaps he thought I was some drug dealer waiting for a rendezvous, or perhaps he was simply wondering why the crazy guy was taking pics of the grasses. 

The world works in mysterious ways, and sometimes it gives a pleasant surprise.

A Slow Motion Carnage

The dried brownish seedheads of Andropogon sp face off with the white fuzzy spikes of Cogon grass (I. cylindrica)

The scenery that lazy afternoon seemed almost pastoral to human eyes, a landscape of tall trees and grasses waving in the breeze. But in reality, such a depiction was quite deceptive.

Grasses and other plants mostly live in slow time. We see them as a green backdrop to the fast movements of the animals that depend and live with them, but they are of course living things. They are dynamic entities, not passive observers. They  fight and cooperate with others and die messy deaths just like animals, albeit at a pace that is glacial relative to our own fast paced lives. They can in fact be every bit as vicious and aggressive as animals.

The forces arrayed. Red arrow shows main cluster of Cogon grass

In this case, the location is Lakes Park in Fort Myers, FL. The combatants are a native grass (Andropogon glomeratus) on one end, and a world-conquering invasive (Imperata cylindrica) at the other end. The situation is dire for the native stand, with the cogon grass massed in an extremely dense cluster next to it. In the photograph above, the erect light-green blades of I. cylindrica are to the right, with its main boundaries marked by the red arrow. To the left are individuals of A. glomeratus, their seedheads rising above the fray like flags set out for battle. Unlike the cogon grass, the native grasses exist in a looser grouping with more forbs in it.

Beautiful seedhead of I. cylindrica

It is easy to tell the two apart. The seedhead on Cogon grass is much slimmer and almost pure white. It is fluffy in texture and quite distinctive. I've seen videos of entire fields of the cogon grass flowers, and they are simply beautiful, notwithstanding the fact the species is a weed in almost every single place where it has taken hold.

Anthers and stigma of I. cylindrica

The battle is joined when the I. cylindrica rhizomes encounter the roots of the native grass. The rhizomes of cogon grass comprise up to 60% of the total biomass of the plant, and not only are their sharp tips capable of piercing through the flesh of their adversaries, but they also inhibit germination and growth of nearby plants through the excretion of allelopathic chemicals. In addition, cogon grass roots are strong competitors for soil nutrients such as phosphorus. 

Cogon grass rhizome

But their most effective attribute is that they quickly allow cogon grass to push into nearby territories as they produce shoots along their length. Established stands of cogon grass can have from 3 to 11 tonnes per hectare of rhizomes, supporting 3 to 6 million shoots.

The battle is joined

It is a silent battle that is waged for nutrients underground, and for light and space above - one whose ferocity and destructiveness is undetectable to passing human beings.

But in the end, this is probably going to be less of a battle than a carnage. The dense cluster of cogon grass will slowly expand into the A. glomeratus territory, following in the wake of the underground rhizomes. When I peered into the area that still had native forbs and grasses in it, I could see numerous cogon grass blades pushing up from the soil (see photo below), the underground rhizomes moving relentlessly outward. 

I knew that if nothing were done about it, that these small blades of grass would ultimately engulf the remaining natives. The doomed natives would put up a fight, but I thought that the next time I visited the park that I would most likely see a much larger mass of white seedheads, and perhaps only a few scattered individuals of Andropogon left. 

The young yellow-green blades of I. cylindrica pushing into enemy territory

The Major Grasses of the Pine Flatwoods and Sandhills of Florida

Any corrections to the identification of the species are always welcome. I do not pretend to be an expert at it.

It's quite interesting to hike and see the various habitats in central and southern Florida.

In addition to the hardwood hammocks which contain broadleaved trees, the most common ecosystem I've seen are the mesic pine and scrubby flatwoods, as well as the pine sandhills, which contain various dominant grasses. 

Shrub and Scrub understory at Oscar Scherer State Park

When I hiked, one of the most common understory denizens of these ecosystems were the very distinctive Saw Palmetto (Serenoa repens), which forms the shrubby layer below the taller pines and Sabal palmetto.

Grasses at Oscar Scherer State Park

But there were also vast areas covered with various grasses in these ecosystems, and it was quite amazing to see them waving in the wind below the tall stately pines and Sabal palms. Although there were smaller stands of grasses in area with a denser canopy, the really large stands occurred when the canopy was more open.

Andropogon along the path at Ocala National Forest

One of the more distinctive species I saw while hiking was Aristida beyrichiana (wiregrass), which is one of the common denizens of these sandhills and flatwoods. This species is a major component of the ecosystem and is so reliant on fire in that it only produces viable seeds when a fire goes through the area during the growing season.

A. beyrichiana at Ocala National Forest

The other grasses all tended to be from the genus Andropogon, with A. virginicus dominating in some areas, in addition to being quite obvious as weedy occupiers of roadsides all over the central and southern portions of the state.

A. virginicus at Ocala National Forest

Another Andropogon that looks somewhat similar, although with much thicker and profuse seedheads was Andropogon glomeratus, although some botanists consider this to be a subspecies of A. virginicus.

A. glomeratus

In addition to the major native grasses, I also stumbled on a few pockets of Imperata cylindrica (cogon grass), which is usually treated when found by workers in the parks.

I. cylindrica (Cogon grass) at Oscar Scherer State Park (straight blades in foreground)

In Oscar Scherer State Park for example, I found a small cluster somewhat hidden close to the periphery of the park. It had probably escaped detection due to being off the main path.

I. cylindrica (Cogon grass) at Ocala National Forest Campsite (in foreground)

At Ocala National Forest,  I found spreading clusters near the area reserved for camping, where it looked to be slowly muscling aside the other understory vegetation.

I also saw some interesting animal species during my hikes. One of the most memorable was when I accidentally bumped into a Gopher Tortoise that was crossing the trail at Oscar Scherer State Park. My wife had passed by a few minutes earlier, and the tortoise must have thought it was safe to cross the road, not knowing that I was lagging behind her (taking pics of everything).

Grasses flank the trail at the Disney Nature Preserve

It withdrew into its shell and would not come out until I had moved far away from it, whereupon it continued to trundle to the opposite side of the road, perhaps muttering about the inconsiderate humans that share its world. 

Grass understory at Ocala National Forest

A Lost Bamboo in Tampa

We were walking along the paved path in Rowlett Park in Tampa Bay, FL when I stopped in surprise.

The trees in the park were a mixture of hardwoods, including oak trees covered in Spanish Moss, as well as pine hammocks. The oaks in particular were quite enchanting in their epiphytic finery. 

But what stopped me in my tracks was a sight that seemed quite out of place in that genteel surroundings Rising up like some mountainous upthrust from between bent hardwood trees and a small palm were the beautiful culms of a large bamboo grass! 

It was as if the trees had been pushed to the side by the more aggressive bamboo, as can be seen in the image above, where I marked the trunk of one tree with a yellow arrow.

I examined the bamboo, and found that its leaves were quite delicate looking, and the culms were an attractive dark green. The bamboo reared up from the surrounding foliage of the hardwoods and clearly had no problem gaining access to the sun.

I wondered who had planted it, and when. Was it there by design, a gift from the landscapers who populated the park? Did some itinerant local gardener lovingly plant it during one of his sojourns? Or perhaps it was even a natural event, a consequence of some seed or bamboo fragment being deposited into this unlikely spot.

I also wondered whether any of the joggers and walkers and passers-by even noticed this unusual resident of their local community park, something almost miraculous in the heart of their thriving urban jungle.

For anyone interested, the coordinates of this unusual bamboo are: 28.02272,-82.43262

Diversity is not the panacea for resisting all invasions

Andropogon virginicus and Aristida beyrichiana in longleaf pine sandhill near Lake Apopka, Florida

Diversity in either species or function has been usually touted as a way for natural communities to resist encroachment by invasive species. This so-called Elton Hypothesis postulates that invasion is favored in areas with lower resident diversity, and that the greater the diversity, the less probability there is for an invasive to gain traction in the community.

There are several mechanisms by which such communities can have this feature. First, a diverse assemblage of species or functional types can use the surrounding resources more completely, and thus prevent invasives from easily being able to exploit an empty niche. Second, a diverse community has a greater degree of interspecific competition, which again means that it will be more difficult for invasive species to gain a foothold.

Imperata cylindrica smothering a roadside in Kissimmee, Florida

Imperata cylindrica (cogongrass) is a tropical and subtropical species that is one of the worst invasive plants in the world, blanketing up to 500 million hectares worldwide and costing governments millions in preventative and eradication efforts.

The species is of particular concern for pine ecosystems (both natural and artificial) in the southeastern USA. In one case, it threatens a forest community called the Florida longleaf pine sandhill, which is anchored by a pine called Pinus palustris, with an understory of oak species and a ground layer of perennial grasses and other herbaceous plants. The major grasses include Aristida beyrichiana (wiregrass) and Andropogon virginicus (broomsedge grass).

The distinctive fluffy seedhead of I. cylindrica in amongst the foliage  in Kissimmee, Florida

Cogongrass invasion of this community not only alters the lower herbaceous and shrub layer, but it slowly destroys the entire pine community by killing pine seedlings and smaller trees due to soil resource competition and an altered fire regime (which is not only more frequent but also significantly larger and hotter than normal). For example, the biomass of pine seedlings after 3 growing seasons in competition with cogongrass was only an astounding 2.4% that of pine seedlings with no competition, and 18% of pine seedlings in competition with only native vegetation (Daneshgar et al, 2008).

Distinctive fluffy seedheads of Imperata cylindrica in gated community in Kissimmee, FL

In order to determine whether plant diversity hinders the invasion patterns of cogongrass, some researchers did a series of experiments in Northern Florida. They selected 5 understory native grasses, forbs, and shrubs, then created mixtures and monocultures of each of the test species. Cogongrass was introduced into these 40 mesocosms, and the amount of biomass and cover of the invasive grass was then monitored (Daneshgar and Jose, 2009).

Contrary to expectations, the most diverse environments did not resist the cogongrass best. Instead, monocultures of the grass A. virginicus (broomsedge) were the most resistant to invasion.  In addition, mixtures that contained broomsedge resisted cogongrass better than mixtures that did not contain this species. 

The authors attributed the ability of broomsedge to compete effectively against cogongrass to its formidable underground root system, which was able to persist even in the midst of the dense roots and rhizomes of the invader, and they suggested that this native species be used to deter cogongrass from overwhelming Florida pine sandhill ecosystems.

Literature Cited

Daneshgar P and Shibu Jose (2009). Broomsedge Communities Are Resistant to Invasion by Cogongrass (Florida). Ecological Rest. December 2009 27:383-385

Pedram Daneshgar, Shibu Jose, Alexandra Collins, Craig Ramsey, Cogongrass (Imperata cylindrica), an Alien Invasive Grass, Reduces Survival and Productivity of an Establishing Pine Forest, Forest Science, Volume 54, Issue 6, October 2008, Pages 579–587, https://doi.org/10.1093/forestscience/54.6.579

Googly Time Machine: Google Street View as a way to see the spread of invasive species

Photo by Dan Clark, USDI National Park Service, Bugwood.org

I was looking at the distribution of an invasive grass species in Florida called Neyraudia reynaudiana (Burma Reed grass) in EDDMaps when I became interested in whether I could view some of the specimens that were in roadside right-of-way by using Google Street View.

This species is a very tall (up to 5 meters) showy grass that looks superficially from a distance like Phragmites australis. It is a threat to the pine rockland communities in South Florida, creating monocultures that significantly increase fire frequency and occurrence (Fusco et al, 2019).

I used EDDMaps to find some clusters of this species next to the Navy Wells Pineland Preserve in Miami-Dade, and viewed the area using Google Street View. There did not seem to be anything at the exact coordinates listed in the report, but I moved around the place and suddenly found specimens close to the intersection of SW 192nd Ave and SW 352nd Street.

The interesting thing is that Google Street View has a feature which allows you to view the same spot across the years, and I used this feature to view the same location all the way back to 2008, when Google Street View itself was only 1 year old.

It was amazing to see how the area seemed pristine in 2008 and 2011, only to suddenly be infested with rows of  N. reynaudiana by 2016!

It seemed that the vegetation closer to the road had either died or been removed (whether due to the grass itself or to some other natural or artificial event), and in their place the invasive grass had taken over. Instead of a tangled web of trees and shrubbery, by 2016 many of the images showed a more open and airy scenery.

I placed the images side by side in order to compare them better, and I have to say that following the spread of invasive species using high level distribution maps is quite useful, but being able to view the past and see how the species spread on the ground gives the process an immediacy and drama that cannot be matched.  

Literature Cited

Emily J. Fusco, John T. Finn, Jennifer K. Balch, R. Chelsea Nagy, Bethany A. Bradley. Invasive grasses increase fire occurrence and frequency across US ecoregions. Proceedings of the National Academy of Sciences, 2019; 201908253 DOI: 10.1073/pnas.1908253116 

Winter Bamboo Shoots: A Grassy Delicacy for The New Year of the Ox

When someone talks about bamboo, the first image that may crop up would  be of pandas in the wild. Some people who grow bamboo for its beauty may also pipe in that it has many horticultural uses. And for many, this versatile grass is well known as a building material, and is used to make not only housing facilities and various equipment, but is also a major component of kitchen utensils such as chopsticks and chopping boards. Some people have even created bamboo toilet paper! 

I was shopping at a Chinese supermarket a couple days back when I chanced upon an example of one other use for this versatile group of plants. Nestled next to a wall was a bin overflowing with whitish conical bamboo shoots! More specifically, they were the tips of bamboo shoots called "Winter Bamboo Shoots", which a quick google search said are dug up and cut during winter, even before the shoots have a chance to emerge into the open air. Each of the shoot tips was fat and heavy, and at $6.99 per pound (or more than US $3 per kg), they were not exactly cheap. 

Today marks the beginning of the Year of the Ox, a change from the unlucky Year of the Rat, and if ever there was a time to celebrate the turning of a season, then it would be now. So thinking, I bought one of the shoots, and today we will be preparing it for dinner using a recipe that I found in the New York Times. I posted the recipe below, and I look forward to having my first taste of bamboo ;-) 

Ingredients

1 tablespoon dried shrimp

1 teaspoon cornstarch

2 tablespoons chicken stock

2 cups julienned winter bamboo shoots (see note)

1 cup peanut oil

2 teaspoons rice wine

2 tablespoons chopped chives

½ teaspoon sugar

 Salt to taste

1 teaspoon sesame oil

PREPARATION

1. Pour boiling water over shrimp and soak 30 minutes. Drain and chop finely. Set aside.
2. Make a paste of the cornstarch and a little chicken stock; stir in remaining stock. Set aside.
3. Rinse and drain winter bamboo shoots. Using julienne blade of a food processor, process bamboo shoots. Dry well in a cloth towel.
4. Heat oil to 375 degrees F. Add bamboo shoots and fry 5 to 7 minutes, until bamboo begins to turn golden. Drain off all but one tablespoon of the oil and set aside bamboo to drain.
5. Add shrimp and stir-fry in the remaining tablespoon of oil.
6. Add rice wine, chopped chives, sugar, salt, sesame oil and chicken stock mixture.
7. Return bamboo shoots to mixture and cook until liquid has been absorbed.

Curious Critter #2: Sporobolus discosporus

Sporobolus discosporus (c) Richard Gill

This amazing looking grass is from Africa, where it was first recorded in 1841. The author of the image notes that it is a tiny species, around 5 cm across, and is found normally growing in very shallow soil on rock sheets. Mr. Johan Volstruis Combrink also notes that the species is part of the ecological process in the Bankenveld Grassland of the Witbank Nature Reserve in South Africa.

This little jewel looks almost like some aloe, and not a grass, and it would be really fantastic to see this in the wild. However, google searches show almost nothing about this species, especially ecological data, which again emphasizes the fact that there are so many fascinating species out there that we know next to nothing about.

Sporobolus discosporus (c) Richard Gill

Unfortunately, more and more plants are landing in the threatened bucket, and once these species are lost, then there is nothing to bring them back again. Let's hope that this jewel of a grass is not one of those species that is lost forever, even before we manage to read its story.

Click here for the species description from grassbase.

Click here for local distribution data.

Sporobolus discosporus (c) Richard Gill

When do grasses break winter dormancy?

A, gerardii cultivar shoots growing with snow banks in the background

It's always a minor sort of miracle to me when Spring comes and the grasses that have overwintered by going into dormancy burst into new growth. This is especially true for the warm season grasses like Imperata cylindrica (Japanese Blood Grass, aka Cogongrass), Miscanthus sinensis, and Panicum virgatum, which "die back" completely during the cold season and re-emerge as new shoots. Last year, I noted down this process in late April, and I expected the same timing this year.

I had bought some native ornamental grasses during Fall, and I had been keeping them in my garage in order to lessen the possible stress of the pot bound plants due to extreme cold weather. Because I also store my tropical aroids in the same garage, I added a lamp that switched on every night for about 5 or 6 hours. The grasses were kept slightly away from the lamp, but they nevertheless must have gotten some illumination. Temperature in the garage was around 11-12 C.

A week or so ago I was surprised to discover that one of the Andropogon gerardii cultivars ('Blackhawk') had suddenly produced new shoots. This was unexpected since it was only late January, and in fact it snowed outside a few days later. Such early and premature breaking of dormancy normally would be a problem for the grass. Above ground shoots that had been prematurely produced could be killed by any sudden cold.  

I can only surmise that the warmer soil temperature in the garage might have caused the premature awakening of this particular cultivar. Triggered by the warmer temperatures, the grass had used its carbohydrate reserves to push out the culms. which caused me to wonder what would happen if global temperatures on average continue to rise. Would more and more grasses and other plants in colder northern climes break dormancy earlier during the year?

Some researchers did some experiments to answer this question. They took dormant Panicum virgatum (switchgrass) and Spartina spectinata, both of which are being studied as possible sources of biofuel, and grew them under ambient lighting, but with temperatures significantly higher than normal (Guo et al, 2017). 

They found that both species grew prematurely under the warmer soil temperatures, but the shortening photoperiod from early Fall to late Fall was confusing. They both ceased to grow, with P. virgatum maintaining the shoots above ground in a static condition, but S. spectina allowing the shoots to die back.

The result of the experiment confirmed the importance of photoperiod to the early growth of grasses after winter dormancy, and hinted that warming global temperatures might cause problems for grasses and other plants that break winter dormancy prematurely. The depletion of carbohydrate reserves in the rhizomes to power the new shoots, only to see these new shoots die due to sudden cold temperatures, might affect total biomass production and the overall fitness of the grass during the growing season.  

Literature Cited

Jia Guo, Arvid Boe, Do-Soon Kim, D.K. Lee. Growth and Development of Two Perennial Grasses in Ambient Light Conditions during their Natural Dormant Period. Crop Science, 2017; 57 (4): 2213 DOI: 10.2135/cropsci2016.09.0823

Barreling Towards Extinction: Plant Families in Peril

It's no secret that there are many endangered species among plants, but I was still surprised at how many are threatened by habitat destruction, invasion, and other anthropogenic factors. 

The International Union for Conservation of Nature (IUCN) is the global authority on the status of the natural world and the measures needed to safeguard it. This organization maintains a publicly accessible database of species which have been evaluated called The Red List, which you can view here. 

In this database, they have categorized species based on several criteria and grouped them according to their risk of extinction. For those species where enough data is available, the categories include:

• Least Concern - species have been evaluated against the red list criteria and are not threatened or extinct
• Vulnerable - species have been evaluated with the best data possible and are at high risk of extinction in the wild.
• Endangered - species have been evaluated with the best data possible and are at very high risk of extinction in the wild. 
• Critically Endangered - species have been evaluated with the best data possible and are at an extremely high risk of extinction in the wild. 
• Total Threatened - a sum of the species in the Vulnerable, Endangered, and Critically Endangered lists.

I was reading about an endangered grass  in California, and this prompted me to see how many grass species are lumped into this bucket. So I took a look at the absolute numbers of grass species in the Red List database, subtracted those species which have not been fully evaluated (a grouping called  Data Deficient in the IUCN), and calculated percentages for each of the categories listed above.

It turns out that a bit more than 20% of the Poaceae species in the database that have adequate information are Threatened, which was a number that seemed a bit high to me.

But imagine my surprise when I decided to look at other plant families.

More than 50% of the species in the Orchid, Daisy, Palm, and Cycad taxa are Threatened, with the Aroids coming up to that percentage as well (45%). Indeed, an amazing 63% of Cycads are in the Threatened category! These are shocking numbers to me, and they shine a light on the need for more action in terms of preserving our plant biodiversity.

But before you go into full panic mode, it should be noted that there are caveats to the numbers calculated above.

1. The total number of species listed for many of the taxa in the Red List database is only a subset of the actual number of species in the world.

For example, although the estimated total species in the family Orchidaceae is around 30,000, only around 1400 are listed in the Red List with enough data to make a judgement call on their status (approx. 5%). In the case of the Araceae, only around 7% of the 3700 species worldwide have been fully evaluated, although almost half of that 260 species of Aroids are listed as Threatened.

However, balancing this is the fact that in some taxa, most of the species are already included in the database. For example, it seems almost ALL 300+ species of Cycads in the world are already listed in the Red List, which means these plants are really in dire straits, given that more than 60% are Threatened.

2. There might be a slight bias in the species included in the database towards those that are in peril already. That is, researchers might tend to focus on plants that they believe are in trouble when there are very large numbers of species in the world.

Thus, as more information is gleaned and more species are entered into the database, it is expected that the percentage of  Threatened species will drop lower.

Nevertheless, such data serves as a warning to us to be ever vigilant in protecting our plant biodiversity.

Field Wars: Revenge of the Rogue Rice

from Wikipedia

Humanity's rise as an intelligent species, and one that today dominates the world, would not have been possible without the grasses. Not only did our species develop in the savannahs those traits that mark us as Homo sapiens during the time when grasslands spread throughout the world, but our very civilization would not be possible without the domestication of various grass species, including wheat, maize (corn), and rice.

The latter of this Big Three directly feeds more than half the people on earth, and was thought to have been domesticated twice, once as Oryza sativa in the Yangtze Valley of China more than 9000 years ago (Molina et al, 2011), and another time  in Africa in the inland delta of the Upper Niger River as Oryza glaberrima between 2000-3000 years ago (Linares, 2002). Amazingly, there is now recent evidence that rice (as a wild Oryza sp) was domesticated in a THIRD continent about 4000 years ago, this time by the mid-Holocene residents of the Monte Castelo shell mound in the Amazon regions in South America (Hilbert et al, 2017)!

Such a tight relationship between humanity and this grass genus would surely mean both benefit greatly from the association, and in fact its mutualistic relationship with people has made rice one of the most common plants in the world. But you would be mistaken to think that all rice has become soft and meek and domesticated.

There are rebels in the midst of the rice paddies, and their effect on the productivity of the Empire of Man is surprisingly substantial. Some estimates put crop losses due to this rebellion at more than 90% in some fields, and in the USA up to 30% of rice fields can be compromised, leading to more than $50 million in annual losses.

These weedy rice have characteristics that differentiate them from their still-domesticated brethren. For example, domesticated rice has non-shattering seedheads, which simply means that the grains do not have a tendency to break off from the plant and scatter. This makes it easier to harvest and prevent significant losses of the crop. In the case of the weedy rice, easy shattering of the seedheads means the rice gets to disperse its seeds, which is obviously the usual goal of any species. 

Another example of a trait that these rebellious rice have gotten is seed dormancy, which allows them to stay dormant in the soil until conditions are optimal for seedling growth. Such a trait has been taken out of their more domesticated compatriots because farmers tend to collect the seeds of plants that don't have dormancy.

Lin-Feng et al, 2017

One interesting thing about these rebellious rice is that not only were they derived from different varieties of rice, but that they arose during different periods of the domestication and improvement history of rice. The way researchers discovered when each weedy rice broke off from being domesticated was by looking at what types of genes they have in common with the domesticated type (Lin-Feng et al, 2017).

How does that work?

Well, remember that as rice developed over the centuries and millennia, it acquired various domestication genes (e.g. genes for non-shattering seedheads), followed by various improvement genes (e.g. popcorn taste, nice aroma, etc). So for example, if rebel rice #1 has the genes for domestication, but not the improvement genes, whereas rebel #2 has both genes for domestication and some improvement genes, then the researchers can deduce that rebel #1 broke off earlier than rebel #2 during the history of rice. In the image above, the BHA (black hull awned) weedy rice diverged earlier in the process than the SH (straw hull) weed.

"But wait!" You might ask. "If they still have the domestication and improvement genes, then how were they able to get all those weedy traits?"

It turns out that these weeds modified other genes to re-acquire the weedy traits  (such as re-enabling shattering of seedheads), and these genes are not scattered throughout the genome but tend to cluster into genomic islands. These genomic islands that re-create similar weedy characteristic are completely different for each weed type, which means that each rice weed evolved the weedy traits independently using different methods.

Amazingly, it seems rice has a tendency to rebel against domestication, and it repeatedly evolves gene islands that allow it to break from its "chains of slavery"! 

How totally ungrateful! *smh*

Literature Cited

Hilbert, L., Neves, E.G., Pugliese, F. et al. Evidence for mid-Holocene rice domestication in the Americas. Nat Ecol Evol 1, 1693–1698 (2017). https://doi.org/10.1038/s41559-017-0322-4

Lin-Feng Li, Ya-Ling Li, Yulin Jia, Ana L Caicedo, Kenneth M Olsen. Signatures of adaptation in the weedy rice genome. Nature Genetics, 2017; DOI: 10.1038/ng.3825

Linares, Olga F. (2002-12-10). "African rice (Oryza glaberrima): History and future potential". Proceedings of the National Academy of Sciences. 99 (25): 16360–16365. 

Molina, J., Sikora, M., Garud, N., Flowers, J. M., Rubinstein, S., Reynolds, A., Huang, P., Jackson, S., Schaal, B. A., Bustamante, C. D., Boyko, A. R., & Purugganan, M. D. (2011). Molecular evidence for a single evolutionary origin of domesticated rice. Proceedings of the National Academy of Sciences of the United States of America, 108(20), 8351–8356. https://doi.org/10.1073/pnas.1104686108

A time for new planting

FERNANDO AMORSOLO (1882-1972) Oil on Canvas, 1950

In many parts of the world the time for planting new crop is one of hope and joy. It is a symbol of renewal, and the promise of an even better future.

The unlucky Year of the Rat will not end until February 12 (when it will be replaced with the Year of the Ox), but already there has been much rejoicing in the USA. The long night under a leader who did not really care about the environment and disparaged science is finally over.

Here's to hoping that the new seedlings that we are planting today grow up strong and true, and that they yield a rich and bountiful harvest in 2021.

You reap what you sow

By User:Bluemoose - Own work, CC BY-SA 3.0, Wikipedia

"If we enable people in power to lie, you all of a sudden have millions of people doubting an election that was certified in every state. We had seven or eight million more people who voted for [Joe] Biden than for [Donald] Trump. Every state has certified those results. Every court appeal has been turned down. A legitimate election is suddenly questioned by millions of people, including many of the people who are leading our country in government, because we've decided over the last few years to allow lies to be told. This is who we are. You reap what you sow."

- Steve Kerr, Golden State Warriors Coach