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The Greatness of Grasses

Updated: Nov 6, 2023

It's a ponderous activity, seed harvesting. Unlike much of the labor of love that is environmental restoration, it doesn't place huge demands on the body. As a relatively safe activity (save the occasional ankle-twist on a gopher mound), it doesn't place huge demands on the brain either, at least once one becomes comfortable identifying the target plants.

So it leaves a lot of room for contemplation. This year I took a few coworkers on some seed harvesting field trips to some nearby prairie remnants to get hyper-specific in our species inventory, and in the quiet moments when the road noise faded, leaving only the faint whooshing of the breeze through the senescing vegetation, I found myself thinking about the grasses. This was my first true growing season with an interest in grasses, thanks to a wonderful class from the Tallgrass Prairie Center on grass identification called "Grasses for the Masses." Prior to that course I'd known my "big four" prairie grasses (big and little bluestem, indiangrass, and switch grass), and perhaps a handful of other common species.

But this course opened my eyes to a whole new realm of botanical interest. I'd had no idea how many species one could actually find in Iowa's wild spaces, and even less of an idea of how to ID them, but armed with a hand lens to inspect the tiny identifying characteristics and a great guide, I started trying to figure out the more esoteric species.

Earlier this spring I found false melic grass, a subtle, beautiful species at Bloody Run. I'd found it in a goat prairie, but the literature I'd read suggested it favored shady, cool woodlands. A chat with some experts taught me that grasses are woefully understudied, and this species likely doesn't get recognized too often so perhaps the literature has some flaws - or perhaps this particular plant simply hadn't read the literature to know where to grow.

False melic grass

Later in the summer I encountered three-flowered melic grass, a much less subtle, even more beautiful giant. I'd sent some pictures to DNR botanist Mark Loeschke, and to my surprise he requested some herbarium specimens since the state herbarium only had three in its collection. Again, he pointed out this probably comes not from any particular rarity, but rather a lack of recognition.

Three-flowered melic grass

Harvesting seed this fall, I watched as amber waves of grain - specifically, the handsome seed heads of prairie cordgrass - rippled across a Fayette County Prairie, and marveled at how even in a drought year this iconic species could achieve a height of 6' in just a few months. It took me almost 25 years to reach 6', and even then it's only on days when my posture is good.

Prairie cordgrass in flower

For such a ubiquitous guild of plants, I don't think grasses get the recognition they deserve.

They are truly pioneers, in every sense of the word. A disturbed site, absent any intervention, will likely see some kind of grass species arrive first during natural revegetation. Grasses have achieved what almost no other life form has; a representative in nearly every single habitat on earth. Antarctica has only two native species of flowering plants: Antarctic pearlwort, and Antarctic hairgrass.

Antarctic hairgrass

They also represent some of the most advanced biology of anything in the kingdom Plantae. Trees and most flowers grow from the tips out; each season's growth comes out of the previous year. But grasses evolved differently. Their growth comes from the base of the plant (or in some species the nodes on the stem).

Basic grass anatomy

This one nifty trick fundamentally altered just about everything on our planet, from the nature of erosion to the body plans of herbivores and the strategies more ancient plant families needed to compete with this young upstart.

Indeed, grasses are relative newcomers to the tree of life (ha!), having arrived a little over 100 million years go, while their progenitors colonized the land some 500 million years ago.

Tracing the history of Poeaceae has become a fascinating story in its own right. Until this century, common knowledge asserted that grasses only emerged after the dinosaurs had gone extinct, some 50ish million years ago. But in 2005, researchers looking at dinosaur coprolites (fossilized poop) discovered the grass phytoliths, small pieces of near-indestructible silica present in many plants but most concentrated in the grasses.

And you thought I was a nerd - at least I'm not looking at poop fossils... Yet

Then in 2013, another amazing find: an actual fossilized blade of grass, with ergot fungus, from 100 million years ago. Ergot species parasitize only grasses, but such a relationship would take millennia to develop in nature, meaning this discovery pushed back the "minimum start date" for grass evolution by several million years.

But even then, it would take another 70 million years or so for the first true "grasslands" to develop - or so we think, for now at least. That, too, proves a tricky date to pin down, and presently comes from the appearance in the fossil record of herbivores with teeth and jaws specialized for eating grass.

The aforementioned silica makes grasses tough on teeth. It's also the reason that we humans can't eat grass leaves (though my brother used to make me try because he was an older brother and probably thought it was funny). So it takes specialized biology, from dentition to digestion, to convert grass to calories. Once we see that biology in the fossil record we can reasonably infer it evolved to exploit a habitat with abundant grasses.

The pinnacle of graminoid herbivory

Our local grassland, the tallgrass prairie, is even younger still. While the individual species therein all come from much more ancient lineages, their assembly into the astoundingly diverse native prairie has only occurred since the end of the last ice age, just a few thousand years ago.

In that short time, grasslands have come to dominate earth's terrestrial biome, covering more than 25% of the earth's surface. Grasses - the seeds, since we can't eat the leaves - make up around 70% of humans' diet (remember that wheat, rice, and corn are all grasses).

So you could say they've become pretty successful. But let me ask you this - how many grass species can you name?

I'm guessing, unless you're a plant nerd, your list went something like "Kentucky bluegrass... Crabgrass... Umm..."

They have become so ubiquitous we hardly give them a second thought. Heck, you probably think Kentucky bluegrass is native to the United States, but in fact it originated in Europe. Spaniards brought it to the New World, and it did so well in temperate climates that it actually arrived in Kentucky before the first settlers, hence the name.

Kentucky bluegrass, AKA Poa pratensis

Again, that fecundity all comes down to grass' high-tech biology. That one little trick - growing from the base instead of the tips like most plants - have made grass capable of withstanding nearly anything Earth throws at it.

By keeping its meristems (growing cells) close to the ground, grasses can tolerate grazing, fire, trampling, you name it, and pop right back up. Some even like it, responding to this defoliation by producing even more "tillers," AKA sprouts from their basal meristems. Many perennial grasses flower more abundantly following fire, recognizing that the blaze probably decreased their competition.

By curing their aboveground growth each year to a dry, highly-flammable plant skeleton, they actually promote fire. By sending up more tender green shoots after getting damaged, they actually promoted grazing - which allows them to spread even further thanks to seeds carried on grazing animals' fur/feathers or in their poop.

In other words, while most plants evolved to tolerate or avoid disturbance altogether, grasses embraced it. Their older cohorts on the landscape, trees and ferns and flowers, have had to adapt to keep up to the firey world grasses have created.

Some grasses have another trick up their sleeve: C4 photosynthesis. I won't even try to explain the chemistry behind it (I couldn't if I wanted to), but essentially C4 photosynthesis (as opposed to C3 practiced by most plants) enables some grasses to grow in warmer, drier environments.

At the end of the last ice age, warmer, drier conditions set in, and C4 grasses stood ready to take their spot at center stage. Thirstier plants like trees started to die back, and pioneering grasses moved right in. Add a little fire to the mix to keep down the woody encroachment, and there's not much the trees could do to wrest that territory back.

On top of that, most grasses can reproduce by seed, or vegetatively through spreading rhizomes or stolons. And unlike their insect-pollinated brethren in the plant world, most grasses are wind-pollinated and thus more self-sufficient in novel environments.

Last but not least, while almost all other plants deplete soils, grasslands actually build it. They practice their own kind of regenerative agriculture, producing the richest soils on earth - at least with all the natural cycles in place. Put it all together and you have a potent, quick-growing lifestyle that can adapt to all manner of climates and habitats. To me there's a lesson here somewhere. Maybe one of those kitschy t-shirt/post card "think like a..." things.

Think like a Grass: • Embrace disturbance • Seize your opportunities • Be adaptable • Bend, but don't break • Build your foundations • C4 Photosynthesize Okay maybe that last one doesn't work, but I'm on to something.

And I have a good reason to try to spread the gospel of grasses. Temperate grasslands, among all other biomes, have the lowest amount of protected acres on Earth. It's not just Iowa. All across the globe, these ecosystems face the threat of fragmentation, woody encroachment, agricultural exploitation, and urban development.

When we lose grasslands, we lose a part of our own evolutionary history. Many anthropologists posit that we developed our upright gait to look over the tallgrasses of the savannas where humans evolved. Without the domestication of wheat, maize, rice, and other grass crops, we may never have had the resources to develop large civilizations.

By all means, plant your flowers and trees and shrubs. But remember that this is the age of grasses, and without them, this would be a very different place. Looking Back

We all sweated the forecast leading up to it, but the 48th annual Heritage Days proved to be a beautiful weekend.

Many thanks to all the vendors, volunteers, and attendees who make this event so special. A personal highlight this year was seeing and weighing the 2nd largest pumpkin in Heritage Days History.

He's not heavy, he's my pumpkin

Meanwhile, our Thursday seed harvest events pretty much all got rained out because the earth is a cruel mistress who stayed dry all summer only to start raining the second it's time to get out into the fields and harvest, be it soy, corn, or prairie seed. C'est la vie.

Looking Forward

The days are getting shorter, but we still have a few things to get you out and about this fall! The O.W.L.S. will take their last trip of the season to the Richardson-Jakway Historic Site on Thursday, November 16th. Don't miss the chance to see this amazing pioneer homestead and jewel of the Silos and Smokestacks National Heritage Area! On November 18th, the Motor Mill Bridge Lighting will again highlight the outstanding work of the gnomes at Motor Mill. Swing down that night at 5:00 for a proper celebration, or take a leisurely drive all holiday season to see the stunning sight.

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