Grasses all day, every day, and grasses ever after, amen!

My life, as well as the lives of billions of other people, are intertwined with grasses...we are touched by them....from the time we wake up in the morning, to the time we sleep at night.

This was what I tried to convey during a talk with Matt Candelas of In Defense of Plants.

In my case, when I wake up in the morning, I (like literally billions of other people around the world) encounter members of the grass family, or derivatives of it, throughout the day.

The first thing I do in the morning is eat a bowl of oatmeal, and oatmeal of course is from the grass Avena sativa. 

When I eat my bowl of oatmeal, I put  some sugar into the mix of fruits, and around 80% of sugar in the world is derived from a grass, sugarcane (Saccharum officinarum).

I walk out to my car, and I'll see suburban lawns stretching to the horizon, and the turf grass of course is a mix of various grass species. In Florida it would be Stenotaphrum secundatum (St. Augustine grass), Paspalum notatum (Bahia grass) and maybe Cynodon dactylon (Bermuda grass), while in the Northeast you get various mixes of Poa pratensis (Kentucky bluegrass), Festuca spp, and Lolium spp.

Such species are what people normally think of when you mention the word "grass" to them. Ornamental grasses also fall into this category of grasses that are used in landscaping.

When I drive my car to work, the ethanol in my gasoline tank is likely as not made from Zea mays. In fact, around 40% of all corn production is used as bioethanol!

During lunch, I might go out and get a burger, and where would that be without the bread that frames the delicious ingredients between them? Bread of course is from a grass that we call wheat,  (Triticum aestivum and its ilk).

Maybe I also eat some snacks for lunch, and if you are brave enough to look at the ingredients of your candy or chips, you'll probably find something called high fructose corn syrup in it. This is a very common ingredient of packaged foods, because it adds to the sweetness of the food, and this is of course derived from a grass that we already mentioned above, Zea mays (corn/maize).

In fact, if you live in the USA, your body is probably mostly derived from that single grass species. Here is a great documentary that explores in some depth the ubiquity of Z. mays in American life.  

Finally, during some part of the day, I'll probably eat rice (Oryza sativa) during either lunch or dinner (and sometimes breakfast too!). Rice is, of course, one of those grasses that have been essential in the creation and and molding of entire civilizations (which I'll look into next time).

And I'm not even including all the times we use bamboo implements and tools!

So no matter how you look at it, the family Poaceae is by far the most influential and important plant family in the world. It's grasses all day, every day, and grasses ever after, amen!

How I do botanical backgrounding in photographs

Cynodon dactylon (Bermuda grass) in Parque del Amor, Lima, Peru. The beach is down below a cliff, and you can see the waves as they rush to shore.

Note: I am by no means an expert at photography, so apologies for any mistaken notions I may have, but here are a few things I've learned.

I am a big fan of macrophotography, and I have been doing it for several years now.

But sometimes I want to show more than just the specimen, especially when the picture I am taking includes scenery that is well known or significant.

In this case, my goal is to have a sharp foreground showing the specimen(s), but with a soft blurry background that does not take away the scenery completely. In order to accomplish this, you need to create something called a shallow depth of field. 

Bromus tectorum (cheatgrass) in foregound of Continental Divide scenery in Rattlesnake Gulch Trail, El Dorado State Park, Colorado, USA.

Creating this shallow depth of field is more an art than a science, and it involves fiddling with various settings in your DSLR camera, as well as correctly positioning yourself and your subject.  This includes:

1. Aperture

This refers to the amount of light that reaches the camera sensor, and the metric it uses is called the f-stop. The lower the f-stop, the greater the amount of light that reaches the sensor, and the shallower the depth of field (the blurrier the background). 

For example, an f-stop of 3 means more light gets to the sensor, which creates a shallower depth of field than if the f-stop is 9. So using an f-stop of 3 would get you a blurrier background compared to using an f-stop of 9, all other things being equal.

Dactyloctenium aegyptium in foreground and our cruise ship in background (in Costa Maya, Mexico)

2. Focal length 

This refers to how wide your angle of view is, and it also affects the magnification. It is measured in millimeters (mm), and the rule of thumb is that the longer the focal length, the greater the magnification, the narrower your field of view, and the shallower the depth of field (the blurrier the background).

So, a focal length setting of 100 mm provides greater magnification, a narrower field of view, and a shallower depth of field than a lens with a focal length of 20 mm.

Bouteloua dactyloides (Buffalograss) in foreground of Buffalo Bill sculpture in Oakley, Kansas.

3. Distance between camera and specimen

There are also things you can do beyond just fiddling with your camera settings to create a soft blurry background and a sharply focused subject. The distance you keep between your camera and the actual specimen also makes a big difference.

The smaller the distance between the camera and the specimen, the shallow the depth of field (the blurrier the background). 

Sporobolus michauxianus (formerly Spartina pectinata) near Lower Bluestem Trail, Boulder, CO, USA. 

Putting all these factors together, the golden rule of botanical backgrounding therefore is:

In order to get a shallower depth of field (blurrier and softer background) while maintaining a sharp focus on the specimen, you need a lower f-stop, a higher focal length, and a shorter distance between camera and specimen.

Here's an example of how focal length, aperture, and distance to the specimen can affect the depth of field and how blurry the background gets using the same specimen and background.

In the first pic below, the specimen is Avena barbata, with the Moras Salt Mines in the Sacred Valley of Peru in the background. The f-stop used here is 8, the focal length is 20 mm, and I was standing relatively far away from the specimen when I took the pic. Notice how relatively clear the background is when compared to the actual subject of the photo. This makes the picture too "busy", and detracts from the focus of your photograph, which is the grass in the foreground.

Avena barbata (?) in the Moras Salt mines in the Sacred Valley of Peru

Now compare that picture above with the picture below. This is the same specimen, but this time I am using an f-stop of 2.8, a focal length of 100 mm, and I am closer to the specimen. Notice how relatively clear the specimen is, but how blurry the background has become. Normally, I would not want a photo like this when I'm doing botanical backgrounding of my photo (too shallow a depth of field and thus too blurry in back), but it does illustrates how aperture, focal length, and distance to the specimen heavily influences the depth of field and the contrast between subject and background. 

It also highlights how much of an art it is trying to get a good optimal mix between a too-clear background that steals focus from the subject, and one that is a completely unrecognizable blur.  

Avena barbata (?) in the Moras Salt mines in the Sacred Valley of Peru

Sounds relatively simple right? Now good luck with your pics, and I hope this short article helps you when you are taking botanical photographs and want a good background for it.

My camera is a Nikon D3400, and for macrophotography I use a Tokina AT-X pro lens.

ps.

I should note that taking the types of backgrounding pics where the specimen is very close to the ground means more than just worrying about focal length, aperture, and distance to specimen. Most times I need to lie flat on the ground to take pics, or take "blind" pics (taking pics without looking into viewfinder) after adjusting the settings, hoping for a photo that is in focus. Someone mentioned that there is visual equipment that will allow you to take pics while holding the camera at awkward angles, but I don't have that (yet). In the meantime, this is hard work and not as easy as I make it out to be above. 

The Tragic History of the Golden Rolling Hills of California

Drone pic of golden rolling hills along Interstate 5 in California (2023). Note that the road in the photograph is NOT Interstate 5, but a side road from it.

Every time I travel to California, I always marvel at the wide open vistas of the state's iconic golden rolling hills. The trip I took last month to the Golden State was no different, and as I drove along Interstate 5 between Los Angeles and Sacramento, I could not help but compare the beautiful hilly terrain with the flat and somewhat monotonous landscapes of Florida, especially after flying my drone and gazing at the land from tens of meters up.

Ground level view of the hills from an older 2005 pic. Not the same location as drone pic above.

For many Californians, the golden hued hills are just as representative of their state as the Hollywood sign in the City of Angels, or the Golden Gate Bridge in San Francisco. But most of them probably do not know the tragic history of the creation of these scenic wonders. They do not realize that these hills were not always like that.

Instead, the hills before the arrival of Europeans in the 1700s were covered in a patchwork of perennial bunchgrasses and wildflowers. Native grasses like Elymus elymoides, Nasella (Stipa) pulchra, Hordeum jubatum, and other bunchgrasses dominated the landscape. The hills were mostly green all the way until autumn due to the preponderance of perennial plants, a far cry from the golden hue suffusing them today.

Native bunchgrass species Elymus elymoides

These perennial grasses had deep roots that allowed them to withstand drought, and they formed the basis of an ecosystem that had a diverse set of forbs and other plants that provided homes and food for the native animals in the area. They were also long-lived, with some researchers saying that some specimens may have lived for hundreds of years (Marty et al, 2005).

It was into this milieu that the Europeans arrived in the late 1700s, and brought with them (whether accidentally or not) the seeds of what would initiate a major and very rapid ecological shift in the landscape. Seeds of Eurasian grass species were introduced to the continent, along with grazing animals such as sheep and cattle. 

Avena fatua along highway

Instead of being perennials, these exotic grasses were annuals, and when they senesced they turned a golden color. Within a short timespan, they had almost completely replaced the perennials. The latter were not driven to extinction,  but were instead bracketed into increasingly smaller spots by the invading species. They could not withstand the competitive abilities of the annuals, nor the new herbivores that came along with them.

One of the most notable exotics are some oat species, Avena barbata, and Avena fatua. These 2 species have beautifully drooping inflorescence, and are cosmopolitan in distribution. 

Avena fatua with empty and ripened spikelets

From a distance they are mostly a light golden color after senescenece, their bodies coating the hillsides in countless multitudes.   

Empty glumes of Avena fatua

Avena fatua

In addition to the wild oats, other species contribute to the golden hue of the hillsides. Bromus rubens is another exotic that has become a component of the hillsides.  

Bromus rubens

Another species from the genus is called Bromus diandrus, which has beautiful spikelets and is somewhat similar looking to the dreaded cheatgrass (Bromus tectorum). But in the case of this species, the spikelets are much larger and longer.

Bromus diandrus

All the above species, as well as various Hordeum spp, are now called "naturalized exotics" because over the past several hundred years they have become an integral part of the ecosystem of California. They have become so much a part of the state that most people nowadays think they are natives, and even those who find out that they were once invaders cannot repudiate and deny the nice memories they had of driving along the roads surrounded by golden hills. 

But there are newer and more damaging species that have entered into the picture just recently. 

Hordeum (?) sp

These winter annual invasive grasses are also part of the golden hillsides, and they are rapidly conquering ground against the older naturalized exotics. One of the more notorious among them is Taeniatherum caput-medusae (medusahead grass), whose silica-rich bodies allows it to smother the competition and slowly form vast monocultures.

Taeniatherum caput-medusae (medusahead grass)

Another is Aegylops triuncialis, a relative newcomer that is also becoming a big component of the golden hued hillsides.

Aegylops triuncialis

The interesting thing is that some studies have shown that the old native perennials actually can do better against these newer invasives, unlike the naturalized exotics. But unfortunately, the tragic loss of so much of the old natural grasslands has allowed medusahead grass and its ilk to spread almost unencumbered.

Drone pic of golden rolling hills along Interstate 5 (2023)

In the end, it's still ok to marvel and gawk at the beauty of California's rolling golden hills. Change is constant in biological systems, and an irrefutable part of life. Just remember that these are the products of an invasion that started hundreds of years ago, and is still going on today.

Literature Cited

Marty, J. T., S. K. Collinge, and K. J. Rice. 2005. Responses of a remnant California native bunchgrass population to grazing, burning and climatic variation. Plant Ecology 181:101112.

Rogue's Gallery of Exotic Grasses in Sacramento, CA

I was visiting a park yesterday in Sacramento (California, USA), and I chanced upon a scene that tickled my fancy.

Exotic and invasive grasses are not a rare sight in the state, especially since the so-called Golden Hills of the state are the direct result of the introduction of alien species - more on that in a later article. But by a fortuitous coincidence I managed to take a single photograph that had quite a few of the more infamous exotic grasses in it. 

 Included in the image is Taeniatherum caput-medusae, Aegilops triuncialis, Bromus diandrus, and Avena barbata/fatua. Click on the image to expand and try to see whether you can spot examples of each!

A couple of the specimens in the photograph are actually new to me. One was the beautiful (but invasive) Bromus diandrus., which is much larger than B. tectorum (cheatgrass).

 

Bromus diandrus

The other is Aegilops triuncialis, which is commonly called barbed goatgrass in the USA. 

Aegilops triuncialis

As an aside, in addition to seeing Aegilops spp for the first time ever, I also saw my first specimens of Bromus rubens (which has the common name Red Brome here in the USA). This species has an attractive inflorescence, but has proven to be quite invasive in desert shrub habitats and grasslands.

Bromus rubens

Bromus rubens

If scientific names became common (the case of Avena in Peru)

Avena fatua spikelets in Ollantaytambo, Peru

I eat a bowl of oatmeal everyday, and during our trip to Peru I tried to keep the same daily routine. Thus, we visited small grocery stores and super mercados in search of this food item, as well as water and various veggies. 

During one such trip I was startled to notice that the oatmeal packages in the store shelves were all labeled "Avena"!

Oatmeal for 1.30 soles!

Avena of course is the genus name of the oats, including the cultivated species Avena sativa. I have been boning up on my Spanish, and it was a small revelation to find out that in that language, oatmeal is known by the genus name of the plant.

Avena fatua in the Moras Salt mines in the Sacred Valley of Peru

This is I think similar in the way Spanish (and several other languages) use modifications of the species name of corn to designate that particular food plant. The binomial is Zea mays, and in Spanish the word for corn is "maiz", just like some other countries call it "maize".

Spikelets in A. fatua, some showing empty glumes

I've found this custom eminently laudable and something that would help (in a very small way) introduce laypeople to scientific nomenclature. Wouldn't it be interesting if rice is called "Oryza", or barley called "Hordeum"?

Maybe even fictional novels and movies could help spread the use of such monikers. I remember Stephen King, in his Dark Tower novels, uses the word "Oriza" to designate various items in the work that are associated with rice. These included a society of women warriors called "Sisters of Oriza", who wielded plate-like throwing weapons called orizas, and whose founder was named Lady Oriza. 

Seeds between dried glumes

Finally, speaking of  "Avena", during the trip one of the most common field grasses was of the genus Avena, likely Avena fatua. I saw this species all over the Sacred Valley area, including at the ruins of Ollantaytambo and Moray, as well as the town of Urubamba and the Moras Salt Mines. Even though this is considered a weedy introduced species, I've found the plant quite attractive, with its many drooping large and awned spikelets.

Just because it's weedy, does not mean it can't be physically attractive!

Winter is Coming: How Grasses Conquered the Long Freeze

Tundra (By Education Specialist)

There are vast areas of the world where cold temperatures create problems for plants.

Such "cold stress" happens when temperatures that are below what are optimal for plants creates physiological problems for the individual plants. Depending on the species, optimal growing conditions usually hovers between 10℃ and 30℃. 

There are two types of cold stress, depending on the temperatures involved.

Chilling refers to cold stress where the temperatures range between 0℃ and 15℃, whereas freezing refers to cold stress where the temperatures are below freezing (0℃). 

In the case of freezing, plants can respond via two different methods. Freezing avoidance is when the plant is able to delay or even prevent freezing altogether in their tissues. In contrast, in freezing tolerance, the plants do not prevent ice crystal formation, but they avoid damage by controlling the size of the crystals and/or where the crystals are formed. Freeze-tolerant plants can survive even freezing of their tissues, and represent the extreme adaptation to conquering the cold over long time periods.

Deschampsia antartica (c) Lomvi2 - Wikipedia

Grasses initially evolved as tropical plants that loved the warmth. But over time, the grasses have managed to adapt to the cold and have become the most widespread vascular plant family, and present in all continents. Indeed, the grass Deschampsia antartica is only one of two vascular plants that are native to Antarctica, and its optimal growing temperature is an amazing 10℃!

Freezing can kill grasses via the formation of ice crystals. At first, ice crystals form in the extracellular spaces between cells, which causes water to be pulled from the cell interior. The loss of intracellular water (and later solutes) results in dehydration and osmotic stress. As ice crystals continue to form into the interior of the cells, the cell membranes start to degrade and programmed cell death occurs.

The evolution of the ability to tolerate freezing in the Poaceae is fascinating, and is confined mostly to species in two different subfamilies of the Poaceae. Grasses in the subfamilies Pooideae (in the Northern Hemisphere) and Danthonioideae (in the Southern Hemisphere) live in cold temperate continental regions, and they have solved the problem in two different ways. 

Hordeum jubatum of the subfamily Pooideae (Northern Hemisphere)

The grasses in subfamily Pooideae in the Northern Hemisphere all use the C3 mode of photosynthesis, and are commonly called the cool season grasses. They include many turf grasses (such as Poa pratensis or Kentucky Bluegrass), as well as food staples such as Triticum aestivum (wheat), Avena sativa (oat), and Hordeum vulgare (barley). 

The ancestors of the Pooideae evolved about 67 million years ago in small niches during the formation of the Eurasian mountain ranges. In this group, ice binding proteins evolved which decreased the rate of the formation of ice, as well as altering the shape of the ice crystals being formed. These anti-freeze proteins prevent the formation of large crystals that can physically damage cells and tissues.

Cortaderia selloana from the subfamily Danthonioideae (Southern Hemisphere)

In contrast, cold-acclimated grasses from the subfamily Danthonioideae in the Southern Hemisphere have evolved a different method for conquering the cold. The members of this group are also C3 grasses, and include the large ornamental grass Cortaderia selloana (Pampas grass). The freeze tolerant members of this subfamily produce ice-nucleation proteins that allow them to control where ice crystals form. Thus, they can prevent damage by limiting crystal formation in the extra-cellular spaces and the leaf surfaces, but not within the cell interiors.

The independent evolution of such mechanisms by the Danthonioideae and Pooideae to tolerate freezing have enabled grasses to dominate large areas where there are extreme seasonal fluctuations in temperature, and contributed to the grassy world we live in today. 

As an interesting aside, at the other end of the temperature spectrum, C4 grasses such as those in the grass subfamilies Chloridoideae and Andropogoneae - which include corn/maize (Zea mays), the bluestems (Andropogon spp), sugarcane (Saccharum officinarum), and cogon grasses (Imperata cylindrica) - have extended the range of environments conquered by the Poaceae to much warmer and drier climes. 

For a quick look at the difference between C3, C4 and CAM photosynthesis in grasses, click here.

Muhlenbergia sericea of the subfamily Chloridoideae, a C4 grass

Finally, to read more about the fascinating topic of cold adaptation in grasses in depth, check out the references below.

Note: In addition to the specialized mechanisms of freezing tolerance above, grasses can deploy other additional mechanisms for coping with the cold that are beyond the scope of this shirt post, such as accumulating fructan in their vacuoles, using supercooling (for shorter cold spells), and increasing anti-oxidant enzymes.

Phalaris arundinacea of the subfamily Pooideae

References:

Timothy J. Gallaher, T. J. Gallaher, Paul M. Peterson, P. M. Peterson, Robert J. Soreng, R. J. Soreng, Fernando O. Zuloaga, F. O. Zuloaga, De-Zhu Li, D. Li, Lynn G. Clark, L. G. Clark, Christopher D. Tyrrell, C. D. Tyrrell, Cassiano A.D. Welker, C. A.D. Welker, Elizabeth A. Kellogg, E. A. Kellogg, & Jordan K. Teisher, J. K. Teisher. (2022). Grasses through space and time: An overview of the biogeographical and macroevolutionary history of Poaceae. Journal of systematics and evolution, 60, 522-569. doi: 10.1111/jse.12857

Schubert M, Humphreys AM, Lindberg CL, Preston JC, Fjellheim S. 2020. To coldly go where no grass has gone before: A multidisciplinary review of cold adaptation in Poaceae. In: Annual Plant Reviews online.Wiley.523–562.

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