Wednesday, September 29, 2021

A purple find in Mt. Rainier

If you are the type of plant nerd who craves rarity, then the Poaceae is likely not for you.

The adaptability of grasses as a whole means that individual species tend to be geographically widespread and able to exist in diverse environments. There are rare and endemic grasses, but they tend to be in the minority, and most don't really have any unusual features that sets them apart from the rest of the family.

We were hiking the skyline loop near Mt. Rainier in Washington State this September when I stumbled on a grass that really caught my eye. This long trail skirts the side of the dormant volcano, starting at 1600 meters above sea level and gaining altitude to a maximum elevation of more than 2000 meters. The sub-alpine environment is rocky and tree-less, with low lying plants, including various unremarkable graminoids.

But one particular specimen next to the path suddenly made me stop in my tracks.

The grass was half hidden behind one of the many rocks that littered the trail, and its slender stalks ended in gracefully drooping spikelets. It was a rather handsome specimen, but what made me really pay attention was the fact the entire plant was a dark purplish color! In fact, it looked even darker hued than my ornamental Andropogon gerardii 'Blackhawk", and it really stood out in the bright morning sun.

Unfortunately, I did not bring my macro lens on the hike, but I made do with the 50 mm lens and took a few pictures of the plant habit and spikelets..

When I returned home I spent some time trying to identify the specimen from the images I took, and finally decided that it was Vahlodea atropurpurea, which is also called Mountain Hair Grass.

This subalpine/alpine species is fairly rare, though circumboreal, and considered endangered in several places, including California and the New England states. It is not considered globally endangered, but I was still happy to have stumbled on the species during the hike, as its discovery reminded me that it is still possible to find quite unusual grasses even in touristy areas like Mt. Rainier.

Tuesday, September 28, 2021

There's snakes in them Painted Hills!

Painted Hills
The Painted Hills unit of the John Day Fossils Bed monument in Oregon is a beautiful landscape, filled with multi-colored hills that are a testament to the changing environmental conditions in the area over millions of years. But almost hidden among the ground cover is the same hegemonic grass species that is rapidly spreading in the Great Basin.

Medusahead seedheads rise above the surrounding ground cover
We spent a few hours in the park and hiked the five major trails. In all of the trails I found clusters of Taeniatherum caput-medusae. Some trails had only isolated small groups, but others had thousands of individual plants. The species was also relatively easy to identify, with the seedheads sporting twisted awns that made it seem like the head of the fabled Medusa.

It was even possible to determine larger clusters of the species from a distance. The dried grass formed a very dense looking golden mass, which stood out very clearly from the surrounding darker colored ground.

The carpet of medusahead was easy to distinguish on the desert floor
The carpet of medusahead grass serves as a foreground to the beautiful hills

When I moved closer to examine the golden carpet, I found dense thatches of medusahead, the individual plants so close to each other that they formed an almost impenetrable barrier to other species. T. caput-medusae has a very high silica content (which makes it unpalatable to grazing animals for much of its life cycle, with grazing capacities reduced by as much as 80 to 90%), and the thatch is not only slow to degrade but is also a source of fine fuels for any fire. These attributes contribute to its continued spread and dominance over existing plants in an area. 

Dense thatch of medusahead in Painted Hills
The Painted Hills is undoubtedly gorgeous, and this beauty is enhanced by the natural flora that surrounds the hills, whether it be the trees or the sagebrush or the bunch grasses and associated forbs. The continued encroachment and spread of T. caput-medusae in this protected environment would tarnish that beauty and result in a monotypic community that is also very fire-prone.

Monday, September 27, 2021

Snakes in Paradise

Taeniatherum caput-medusae (medusahead grass)
Taeniatherum caput-medusae (medusahead grass)
I visited the  Phoenix Park Vernal Pools in Fair Oaks, California last week.

The park is a designated National Natural Landmark because of its vernal pools, and for those who do not know what these are, vernal pools are a unique type of ephemeral environment which are filled with rain or snow water for part of the year, but which have no inlet or outlet. Vernal pools support an amazing range of plants and animal, some of which are very rare and endangered, and the reason I was there last week was to see whether I could catch a glimpse of the dried remnants of the Sacramento Orcutt grass (Orcuttia viscida) and perhaps Orcuttia tenuis.

Entrance to the Vernal Pool section of the park
If you are wondering why I am so intrigued by these species, then I would strongly suggest reading the article on vernal pool annual grasses from the Winter 2009 edition of the California Native Grasslands Association. You can read the PDF version here. It will go a long way to explaining why  find these rare grasses so fascinating, and why I made a special trip to see them in Sacramento during my West Coast trip.

I arrived in late morning, and there were a few people about. The park environment itself was dominated by the usual mix of golden-hued annual exotic grasses that have reshaped California, with a few trees scattered around. These annual exotics form the iconic golden hills in the state and its neighbors, and were brought over when Europeans arrived a few hundred years ago. 

The typical grasses in the menagerie that I saw included Avena spp (Avena fatua and A. barbata), Bromus spp (B.diandrus, as well as a species that I found quite curious called Briza minima.

In addition to the usual exotic grasses, I also found a colony of the hegemonic invasive grass Taeniatherum caput-medusae (medusahead grass). I have posted about this species before, and how it has been transforming rangeland in vast areas of the West, and it can be recognized by the twisted awns that resemble the snakes in the fabled Medusa's head.

Medusahead with the distinctive twisting awns
The medusahead formed its distinctive dense thatch as it sprawled along a 10 meter section parallel to the trail, pushing aside other grasses. This high-silica thatch prevents other plants species from growing in the midst of the stand of medusahead, and I was alarmed that the infestation might spread further and endanger the vernal pools.

Dense thatch of Taeniatherum caput-medusae (medusahead grass) in Phoenix Park
I took note of its location, then continued to wander the trails for awhile, taking pics but not exactly sure where the actual pools would be. I knew they would be dried up by now, but I had no idea how to distinguish the dried pools from the surrounding grounds. 

Fortunately, I met a local man who was also using the trail, and he kindly pointed out to me those areas which would have been filled with shallow water during earlier in the season. He mentioned that they stood out because wildflowers bloomed from them at one time.

Dark depression that marks the site of the vernal pool
The dry vernal pools were depressions that had a slightly darker color than the surrounding area. One of them was close to where I had been walking, and you can clearly see the outlines of the pool in the image above.

Since we were not allowed to step outside the trail,  I used a drone to view the pool from above, and again the pool was quite obvious from several meters up.
Vernal pool from several meters up.
It was while photographing the pool that I noticed the patch of yellow-white that lay near its center. The patch was quite distinctive, but I could not make out what it was from the trail, so I moved the drone closer to hover over it and took several pics. 

Taeniatherum caput-medusae (medusahead grass)
Possible medusahead grass in center of vernal pool

Imagine my surprise when I looked at the image later on my laptop and discovered that the white patch looked to be a thatch of medusahead grass!

A quick survey of the literature mentioned that this species could be found in the vicinity of vernal pools, and sometimes all the way to the high water mark of such pools. But like many other grasses, it did not seem to be able to proliferate in the pools themselves, so I am at a loss as to how this colony could thrive in this case. Perhaps there was a slight mound in that part of the pool that allowed the medusahead seedlings to take hold.

Whatever the reason, the best course of action would be to positively identify the grass, and take measures to remove these particular snakes from the park, and especially from the pools themselves. Without direct and decisive intervention, this hegemonic species might slowly take over the park, turning it into a monotypic stand of medusahead.

Sunday, September 26, 2021

Curious Critter: Briza minima


I was exploring the Vernal Pool area in Phoenix Park in Fair Oaks, California, when I chanced upon a most curious sight.

At first I thought it was some cocoon that was hanging from a grass stem, but I immediately saw that I was mistaken. What I had thought at first to be of animal origin was in fact the dried seedheads of a grass!

Briza minima  is called shivery grass or lesser quaking grass, to distinguish it from the much larger Briza maxima. This bigger species has many common names, and they include big quaking grass, great quaking grass, greater quaking-grass, large quaking grass, blowfly grass, rattlesnake grass, shelly grass, rattle grass, and shell grass.

Their  unusual forms have made them at times a favorite of the horticultural trade, and they have escaped multiple times and become an invasive in several countries, including the western USA.

When I took one of the delicate pods and shook it, I imagined I could hear tinny sounds emanating from the dried structure. I had to admit they looked quite interesting and I can understand why people could want such a grass in their gardens, but in this case, the results of that desire might be causing environmental problems due to its propensity to escape into the wild.

Monday, September 6, 2021

How roads are aiding our worst plant enemies

Japanese stiltgrass growing on abandoned railroad tracks along Ashokan Rail Trail
I was hiking the Ashokan Rail Trail in New York and noticed how the gravel path was frequently lined with masses of the invasive grass Microstegium vimineum (Japanese Stiltgrass), which crowded out other invasives, as well as the native flora.

This predilection of the species for roadsides and paths is one that I am familiar with, and so once I got home I looked up whether there was any reason for its behavior. My first thought was that roadsides created an environment with higher light levels than the interior of the canopy, but it turns out there are other reasons why such man made strictures aid invasive plants in general

The characteristic silver midrib of Japanese stiltgrass
Large scale studies have shown that M. vimineum presence in forests was strongly correlated with the presence and proximity of roads and other man-made paths. The probability of finding this species along the east facing sides of roads was as high as 83% in one study area. In addition, experiments revealed that the natural spread of this species was greatest in patches closer to roads, and that these patches also tended to have higher populations.  There was something in the areas around roads and paths that proved advantageous to the proliferation and spread of this invasive species,

Japanese stiltgrass lining the sides of a hiking path
One interesting and important finding from studies of M. vimineum is that the species if left to itself spreads very slowly, with seeds landing only 1 to 2 meters away from the parent plant. This was perplexing because land managers noticed that Japanese stiltgrass can quickly spread throughout an entire forest within a few years, which implied a rate of invasion that was orders of magnitude faster than it should be.
Japanese stiltgrass expanding from roadside into forest interior

It turns out that human activity along the forest roads is one of the major causes of the rapid and unnatural spread of stiltgrass in invaded forests, whether it's from hikers picking up seeds as they trudge along hiking paths, or vehicles doing the same along passable roadways.

In addition, the forest roads themselves can create conditions that are environmentally advantageous for this invasive grass. For example, the use of limestone gravel in many unpaved roads can raise the pH of the surrounding soil, which is favored by M. vimineum.

Unfortunately, it is neither possible nor perhaps even desirable to completely remove all human structures from parks and other forested areas in a quest to return the forests to their original pristine condition, But we can at least minimize the negative impact we have on these environments through more studies that delineate the many ways our presence in the natural world affect the denizens of the forests.

Sunday, September 5, 2021

Andropogon gerardii as an ornamental

Andropogon gerardii "Blackhawk"

 I've been interested in using various ornamental grasses in my yard, and last year I finally decided to test some of the Andropogon gerardii cultivars in the market.

I was not convinced this species had what I wanted in an ornamental grass, but I wanted to at least make sure I wasn't missing something.

Andropogon gerardii "Blackhawk"

I bought an A. gerardii "Blackhawk" and an A. geradii "Raindance". The former surprised me this Spring by prematurely coming out early, but then seemed to have problems and its above ground structures wilted. It was reduced for awhile to a few small stems that sprouted from the periphery, and I fully expected the plant to die completely or to only come back next Spring.

However, several months later the ornamental grass had come fully back, and had even pushed out tall inflorescence that towered above the shorter leaves.

Andropogon gerardii "Blackhawk"

I took some time to take some macro shots of the flowerheads of the 2 cultivars, but I must admit I am not a big enthusiast of the species as an ornamental. The flowerheads came up at different heights, and I just could not shake the feeling that the "Raindance" especially looked like it was simply a grassy weed that had not been pulled out.

However, the cultivar "Blackhawk" has at least one redeeming feature, and that is its dark color. The leaves right now are a very darkish red, and they are supposed to turn almost black in late September. This unusual color of the cultivar perhaps makes up for the somewhat disappointing flowerheads.

Overall, I think the Andropogon cultivars do not match the beauty of other native ornamentals, such a Panicum virgatum or Schyzachyrium scoparium.