Here come the Four Horsemen of the Prairies

Panicum virgatum in Open Space area, in Broomfield, CO

Colorado is short grass territory (or at the least the eastern part of the state is), but as summer here is getting into full swing, I noticed that some of the iconic tallgrass prairie species are starting to show themselves.

The Four Horsemen of the Prairies refers to four species that tend to dominate the prairies farther east. The ensemble cast includes Andropogon gerardii (Big Bluestem), Panicum virgatum (Switchgrass) , Schizachyrium scoparium (Little Bluestem), and Sorghastrum nutans (Indiangrass).

Sorghastrum nutans in Broomfield, CO

I must admit that I was not really looking for them, engrossed as I was by the more western oriented species here, but I was walking along one of the Open Spaces in Broomfield when I spotted what looked to be Panicum virgatum in flower. The largish specimens lined part of the path, and a quick check of the flowerhead confirmed the identity.

I've always been a fan of this species as an ornamental, but seeing it in situ always is a treat, especially when in flower.

Sorghastrum nutans in Broomfield, CO

The second "horseman" I saw was one that for one reason or the other, I have not encountered much. This time, I found a slew of Sorghastrum nutans (Indiangrass) flowering along a sidewalk in Broomfield, CO, as well as in the various trails around Boulder.

Many people consider it a beauty, but personally, the fleshy colored and awned flowerheads of the species has never struck me as particularly attractive. Nevertheless, I was enchanted by the small flowerheads, which had escaped the mower blades by virtue of being shielded underneath some metal handhold along the path.

Schizachyrium scoparium along sidewalk in Broomfield, CO

And then there's Schizachyrium scoparium (Little bluestem), which I have owned as an ornamental and is an attractive plant to me. Unfortunately, the single specimen I have stumbled upon so far was still in the earlier stages of flowering, but I am looking forward to seeing more of this species going forward. 

Ladybug on Bothriochloa ischaemum(?). Where art thou Andropogon gerardii?

I was also on the lookout for the biggest horseman of all - Andropogon gerardii (Big Bluestem), but all the lookalikes I found at first seemed to be of some other species...specifically, Bothriochloa ischaemum, which is called yellow bluestem or King ranch Bluestem (in Texas).

Andropogon gerardii near Enchanted Mesa Trail, Boulder, CO

There are trails in that city called Lower and Upper Bluestem trails, and so I expected to find bluestems in the area, which I did. Unfortunately, most seemed to be yellow bluestem (Bothriochloa ischaemum) at this time.

It did not help that my identification skills aren't the best, but I finally found specimens of this large species during one of my hikes in Boulder. Not, as it turns out in the bluestem trails, but in trails closer to Chautauqua Park. Perhaps later in the season this tallest of the Four Horsemen will make its presence more widely known.

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

Finally, I also found a really tall and attractive species that I identified as Sporobolus michauxianus (formerly Spartina pectinata). This is commonly called Prairie Cordgrass here, and it has amazing

pinkish anthers! When I first saw it from a distance I thought it was some weird A. gerardii, but I'm happy to have met the acquaintance of another spectacular looking member of the Poaceae during my trip to Colorado.

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

Mass Flowering of Native C4 Grasses in a Florida Savanna

Andropogon ternarius (syn. Anatherum cabanisii)

Update: Thanks to an unknown commentator and the infernal never ending work of taxonomists, the following corrections are added - the Andropogon ternarius depicted is synonymously termed Anatherum cabanisii, while the Andropogon glomeratus here is Anatherum tenuispatheus, which is synonymous with Andropogon glomeratus var. pumilus. 

Update 2: Added comments and pics of Saccharum giganteum.

The passing of the seasons can be seen in the regular changes in the grasses that make up a landscape. Even here in subtropical Florida, the coming of Fall heralds the flowering of many of the C4 grasses that dominate the longleaf pine savannas that are a marvelous (but threatened) fixture of the natural environment. 

Andropogon glomeratus (syn. Anatherum tenuispatheus)

I visit the Nature Conservancy's Disney Preserve in Kissimmee fairly regularly, and during my visit this late October, the surroundings were suddenly aglow with the sudden flowering of several C4 grasses. 

If you remember from earlier posts, C4 grasses have a specialized carbon-concentrating photosynthetic mechanism that allows them to be more efficient in hot and arid conditions, and they tend to grow fastest and flower during the latter parts of the season. 

Andropogon ternarius (syn. Anatherum cabanisii)

Whereas before, the preserve was a somewhat monotonous landscape of Serenoa repens (saw palmetto) and various smaller grasses like Aristida beyrichiana, with longleaf pines interspersed at almost regular intervals, now the area was dominated by the visually arresting inflorescence of different Andropogon spp. and a few other C4 grasses.,

Sorghastrum secundum

I admittedly am still learning how to identify the many Andropogon spp, but there were a few species that stood out enough that even I was able to identify them. Among the most beautiful was Andropogon ternarius (locally called Splitbeard Bluestem in this area, syn Andropogon cabanisii). Each inflorescence contained a pair of silvery racemes that formed a distinct V, with the awned spikelets giving it a beautiful feathery appearance.

Sorghastrum secundum

Some other Andropogon spp that were in flower included A. glomeratus (Bushy Bluestem, syn Anatherum tenuispatheus), A. virginicus (Broomsedge), and others that I cannot yet identify to species. 

Sorghastrum secundum flowerheads rise up from the understory

An interesting new grass that I found was Sorghastrum secundum, which is related of course to the more well known Sorghastrum nutans (locally called Indiangrass). Unlike S. nutans, the spikelets in S. secundum are all located to one side of the raceme, and this gave rise to one of the local names for it, Lopsided Indiangrass.

Sorghastrum secundum with mostly detached spikelets

But perhaps the most beautiful species that graced the preserve during my visits was Muhlenbergia sericea. This grass is also known as Muhlenbergia capillaris var filipes, and known locally as Gulf Muhly and Sweetgrass.

Muhlenbergia sericea (capillaris)

The purplish inflorescence waved easily in the breeze, and looked almost ethereal when seen in front of the sun's bright rays. M. sericea and its relatives are used often as ornamental grasses here in the peninsula, although I noticed that there is a hit and miss quality when it comes to the lavishness of its flowering in cultivation.

Muhlenbergia sericea (capillaris) line the hiking trail

People were not the only ones appreciative of this species. I also saw a juvenile alligator hiding in the shade of one of the M. sericea specimens (see image below).

An alligator under Muhlenbergia sericea

Perhaps most remarkable of all were vast fields of Saccharum giganteum (locally called Sugarcane Plumegrass), which lay behind rows of Andropogon glomeratus that lined the road leading in and out of the preserve.

Andropogon grasses were in abundance at the preserve (forefront). The tall grasses behind it in the far distance were Saccharum giganteum.

I could not identify them at first due to the distance, but after an unknown commentator mentioned the name, I later came back and waded into the field and took pics.

Saccharum giganteum

The culms and sheaths were quite hairy, and so too were the flowerheads. Macroshots revealed that the spikelets had a ring of long white hairs rising from the base, and straight awns that nailed the ID as S. giganteum.

Saccharum giganteum flowerhead. Inside pic shows expansion of the inflorescence against an aroid backdrop.

Saccharum giganteum spikelet showing long callus hairs and awn.

In the end, there were quite a few species that were in flower that I could not identify at the time. This was especially true for the Andropogon spp, which I am still learning about. Nevertheless, I'll be sure to drop by again soon to continue my exploration of this beautiful grassland, and perhaps someday I'll be able to name all the various species I encounter.

Native grasses during a hike at the Environmental Education Center at Lord Stirling Park (Great Swamp National Wildlife Refuge)

Inflorescence of Andropogon gerardii

Little did I know when we started our hike at the Environmental Education Center (EEC) at Lord Stirling Park that I would finally encounter and identify one of my more sought after species, one of the members of the legendary "Four Horsemen" of the Tall Grass Prairies. These 4 native grasses (Andropogon gerardii/Big Bluestem, Panicum virgatum/Swirchgrass, Sorghatrum nutans/Indiangrass, and Schizachyrium scoparium/Little Bluestem) dominated vast swathes of America before giving way to the spread of another type of grassland with the introduction of corn. 

I was not expecting much because the EEC is located in the Great Swamp National Wildlife Refuge, a remnant of the Wisconsin Glacier, which retreated around 11,000 years ago to form the New Jersey Wetlands. So I thought I would see lots of marshy areas, wilt under the high humidity, and of course be attacked by lots of mosquitoes.

What I did not expect was a very well maintained, and honestly impressive trail system, but that's what I saw. A significant proportion of the path was on wooden boardwalks, which was impressive, and the trails were wide enough that you didn't have to touch vegetation on either side - always a recipe for picking up ticks. It even had a garden near the EEC building, with labeled plants, though not many of the plants were flowering at the time we went there.

Carpet of Microstegium vimineum

We found a trail map of the area and decided that we would move from trail to trail along the periphery of the place, thus maximizing our hiking time. We first traveled counter clockwise along the yellow trail towards Lenape Meadow, and as usual I saw lots of Microstegium vimineum (Stiltgrass) covering the sides of the path, as well as sometimes extending deeper into canopy. This invasive grass is the bane of forest managers, and I had already grown used to encountering it every time I entered some forested area. You can identify stilt grass by the bamboo-like leaves as well as the silvery stripe that runs along the upper leaf surface.

Close up of leaves of Microstegium vimineum

Fortunately however, we did encounter some other plants along the way, including a quite striking plant with dark red flowers, which I later identified as Lobelia cardinalis.

Lobelia cardinalis

We also saw lots of cattails (Typha species) as we crossed the Boondocks Boardwalk along the north end of Lord Stirling Park. The sight of so many cattails was interesting and unexpected because this plant is being pushed aside by a grass called Phragmites australis in most places.. The reason for its health in the area seems to be because the park managers are actively controlling populations of the invasive grass.

Cattail

But what excited me at first was the sight of clumps of S. scoparium (Little Bluestem) at Lenape Meadow.

A clump of S. scoparium at Lenape Meadow (center of pic)

I've always been fond of this species ever since I saw fields of it in New Hampshire, with the distinctive red flowerheads arrowing stright up into the air. Of course, it's only early August, so the S. scoparium I saw at Lenape Meadow still had not gained their full beauty.

S. scoparium in New Hampshire

However, my delight at the discovery of my old friend Little Bluestem was nothing to the amazement that I experienced when we passed Alexander Meadow at the extreme southwest of the park. There I saw a field of grass that almost made my jaw drop. Rising more than 3 meters into the air were flowerheads that looked like turkey feet waving in the air. I had come upon my first field of A. gerardii (Big Bluestem)!!!!

I believe I have never encountered this species before, ever since I started learning more about grasses last year.  The distinctive turkey feet flowerheads and towering height made them almost instantly recognizable, and we passed through the meadow surrounded by these impressive grasses.

A. gerardii inflorescence, looking like turkey feet

I took a few macroshots of the spikelets, which were tightly appressed and had a few dangling yellow or red anthers, although it was obvious that full anthesis had not yet started for many flowerheads.

I also saw quite a number of P. virgatum (Switchgrass) in the field, their wispy flowerheads forming almost a mist-like cloud above the grasses. This species is the 3rd member of the Four Horsemen of the Tall Grass Prairie present in the park, and I had a feeling the 4th and final member (Sorghastrum nutans) might also be somewhere there, although I did not have time to explore the place further.

P.virgatum flowerheads

In the end, it was a very nice and productive hike, although we did sweat throughout the experience, and were bitten by quite a few mosquitoes. 

A native among the Stiltgrass - Sorghastrum nutans (Indian Grass)

I've gotten so used to seeing Japanese stiltgrass (Microstegium vimineum) during hikes, that it's always nice to see some other beautiful grass species along the trail.

The hike at Lewis Morris County Park in Morristown, NJ was turning out to be the same, with carpets of the invasive grass lining the sides of the trail, when I found myself looking at a tall stately looking grass in an open clearing. The specimens were notable for the large yellow stamens protruded from the spikelets.

The grass turned out to be Sorghastrum nutans (Indian grass), a warm season native that used to be a common component of the tallgrass prairies that used to dominate the American landscape.

This was an awesome find, and I hope to be able to hike the trail again and take more photographs of this majestic species.