The Case for Urban Open Spaces

Bouteloua dactyloides staminate spikelet (from another location)

One of the first things I noticed here in Colorado is the prevalence of land called "Open Spaces". These Open Spaces are preserved land that is not developed, although they may be adjacent to the usual parks and other recreational locations.

According to the department that manages these areas in the city of Boulder:

The open space lands teem with native plants and wildlife and are home to threatened and endangered species. They serve as a buffer between Boulder and nearby development. They sustain agriculture uses and add untold benefits to the natural environment - clean air, water, and earth. The lands shape the urban mosaic of the Boulder Valley and provide residents with passive recreation opportunities. Trails are used by walkers, hikers, bicyclists, horseback riders, dog walkers and other passive recreational uses.

I visited one of these Open Spaces in nearby Broomfield, which has kept their city beautiful by preserving large tracts of land. In the Open Space that I visited there, walking paths crisscrossed the place, and people were jogging, walking their dogs, and generally just enjoying nature. I did some botanizing one morning, and found many native grasses, although they were outnumbered by the usual naturalized exotics that have become ubiquitous wherever humanity has taken hold.

Part of an Open Space in Broomfield, CO

I spent  an enjoyable morning just walking the paths and looking at the critters, and managed to identify some of the major species during my botanizing. As always, I am always open to corrections of my identifications.

One of the most notable denizens of the area was Bromus inermis, which existed in large clusters and is commonly called Smooth Brome. You can identify it not only by the recognizable spikelets and habit, but by a W crimp in the middle of the leaves. This species is an introduced forage grass, but it has become somewhat invasive in many places.

Bromus inermis

The native Pascopyrum smithii (called Western Wheatgrass here) was also quite abundant. It is rhizomatous, and so exists in the area in large groupings.

Pascopyrum smithii

Close to it I also saw Thinopyrum obtusiflorum, which looks somewhat similar, but is significantly taller than its neighbor. This species is not native, but had been introduced from Eurasia. It has a few common names, such as tall wheatgrass, rush wheatgrass, and Eurasian quackgrass.

Thinopyrum obtusiflorum

Another naturalized Eurasian species was also quite abundant. Agropyron cristatum is called crested wheat grass, and the sight of its flowerheads en masse was quite attractive.

Agropyron cristatum

There were also stands of what I first took to be escaped cultivated plants. but which may instead be a native called Hordeum brachyantherum (meadow barley). These were one of the taller species in the community, dwarfing everything but some of the Thinopyrum obtusiflorum specimens.

Hordeum brachyantherum

The smaller species I found along the sides of the path, and included native grasses from the genus Bouteloua (which has become one of my fav genera, and which I'll explore more in a later article).

Bouteloua gracilis (called Blue Grama grass here) was in evidence along the margins, their distinctive flowerheads dangling bright green anthers. This species is one of the dominant inhabitants of the short grass prairies in Eastern Colorado.

Bouteloua gracilis

I also found some specimens of the equally diminutive Bouteloua dactyloides (called buffalo grass here), another dominant species of the short grass prairies that has been used as turf. More on this later, but it is one of the few dioecious grasses, with some individuals having only staminate flowers,  and others only pistillate flowers.

Bouteloua dactyloides (staminate spikelet)

Other species that I found included the natives Panicum capillare, Bouteloua curtipendula, and Hordeum jubatum, as well as a few clusters of the invasive Bromus tectorum. In a creek, I even found a lone cattail (Typha sp, not Poaceae) surrounded by the invasive Phalaris arundinacea (Reed Canary Grass).

Phalaris arundinacea surrounds a lone cattail (Typha sp)

The variety of species was fantastic, and I loved the time I spent botanizing. All in all, I have to say that I am fully and heavily in support of creating such Open Spaces. I would rather see natural areas like these preserved, than more gated communities, mini-malls, McMansions and parking lots. 

As noted above, some of the advantages include:

• They serve as home to threatened and endangered species.
• They serve as a buffer between a city and nearby development.
• They sustain agriculture uses and add untold benefits to the natural environment - clean air, water, and earth.
• The lands shape the urban mosaic and provide residents with passive recreation opportunities. Trails are used by walkers, hikers, bicyclists, horseback riders, dog walkers and other passive recreational uses.

In addition, I believe Open Spaces give an airy and open vibe to a city, provide habitats for a large variety of plants and animals, and serve as a shining example of how nature and people can coexist together.

Kudos to the city of Broomfield, Boulder, and all the other enlightened communities in Colorado that have the foresight and the perseverance to protect the natural beauty of the land!

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 donax, Neyraudia 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.

Bee mimicking fly on flowers of Phalaris arundinacea cultivar

I was taking macro photos of the flowers of my ornamental Phalaris arundinacea 'Strawberries and Cream" when I noticed several small (less than 5 mm) bee-like insects rummaging on the inflorescence.

The vast majority of grasses are wind-pollinated of course, but there have been cases of insect pollination, including by hoverflies.

The specimens visiting the grass flowers were identified as Toxomerus geminatus by Jeff Skevington in a Facebook group for hoverflies of the world.

In these hoverflies, the insect eats the pollen directly using its extended proboscis, and facilitates pollination when pollen sticks to it and transfer during its visit to another flower.

There were perhaps 3 or 4 total of the bee-mimicking hoverflies on the flowers at any one time, and  at first I was thinking they actually were small solitary bees, although a quick look at the photos shows the single pair of wings and stubby antennae that mark them as flies.

I have to admit it was interesting to see them at work, although taking good pictures was doubly difficult because of the high winds at the time.

A couple more pics below. Enjoy!

Bloom time for Phalaris arundinacea (Reed Canary Grass)

There is this small lake that has a paved path going around it, and we usually walk the path during our afternoon exercise.

When we visited the lake two days ago, I noticed a stand of tall (1.5 m or so) grasses that had started blooming. The grass had pushed aside other plants and formed a dense barrier along the side of the path.

I do not believe I had seen this stand in years past, and I noticed that scattered around the lake were other similar specimens, although much smaller and existing only singly or in somewhat small groupings.

I examined the plant and suddenly realized that these were wild Phalaris arundinacea!

This C3 invasive grass has somewhat loose panicles, and each spikelet has a single fertile floret and two much smaller sterile florets surrounding it. Under my macro lens the pink-purple anthers looked deflated, and here and there I could see white feathery stigma poking out. 

If you look closely at the macro shot above, in the spikelet in center you can see what looks to be 2 stigma and 3 clustered anthers poking out.

The ligule is membranous and around 5 mm in height, and the collar region has a pale yellow color.

This species has distinct populations that are both native and transplants from Europe, although there has been lots of mixing going on. But in general, P. arundinacea can become invasive in some wetland habitats, were its vigorous rhizome system allows it to exclude other plants and create the monotypic stands that I noticed in my lake.

I tried to remember whether this stand was here last year, and I don't believe it was. The pandemic perhaps has meant less maintenance of the surrounding area, and the species has suddenly become more visible. Nevertheless, it would be interesting to continue monitoring the stand and see whether it continues to spread and overwhelm the plants around it as time passes.

Phalaris arundinacea as an Ornamental Grass

Phalaris arundinacea (or Reed Canary Grass as it's known here locally) is a perennial C3 grass that has become invasive in certain wetland areas, where it forms dense monotypic stands as it spreads using its thick rhizomes.

The species has become important for various commercial uses. For example, its ability to grow in contaminated soil has made it a prime candidate for phytoremediation, and as a very fast grower it has also been used in biomass production.

The genus has also become infamous because of its ability to poison animals. P. arundinacea contains tryptamine alkaloids, and may also accumulate high levels of selenium. It has a history of poisoning cattle and sheep, and a related species was involved in the "drunken" behavior of kangaroos in Australia, which can end in the death of the animal.

The wild form of this species is green and very tall, reaching more than 2 meters high. But there are also several ornamental varieties which have become popular in the trade.

I bought P. arundinacea 'Strawberries and Cream' last Fall and planted it in an enclosed cement container. The grass thrived, and this Spring I had to transplant out some of the plants or it would have engulfed the Calamagrostis acutiflora (Karl Foerster?) that shared the enclosure with it.

I love the leaves of this grass, which are strikingly white and green, with some pinkish highlights. The species also seems pretty tough, and a few days after transplanting them out, the somewhat withered looking grasses had pushed out new culms.

New stems poking out soon after transplant

I expect they will soon spread quickly to fill the available space, hopefully before the heat of summer, as this is a cool season grass.

I love working with tough species!