One Year Anniversary!

Ornamentals at Lake Louise, Baanf National Park, Canada

I just realized I went right through the anniversary of this site without knowing it,

About a year ago I decided to chronicle the encounters I've had with this most important of plant families, and it's been a doozy of a journey indeed. From the burning hot sands of Great Dunes National Park and White Sand National Monument, to the forested gloom of Shenandoah and many other places in between, grasses have become a major part of my travels.

I've learned so much, and I've had great help in identifying some of the species I've encountered, mostly from those groups in facebook that I frequent.

I hope people who read this have learned as well, and have like me, grown even more appreciative of the myriad ways grasses have impacted and continue to influence our lives.

Sporobolus airoides at White Sands National Monument

Here come the C4s! Warm season grasses start flowering

Spikelets of Schizachyrium scoparium

I noticed that two of the grasses I care for at home have started to flower, and both are warm season grasses.

A warm season grass of course refers to a species which reaches its optimal growing rate when the season temperatures are high, normally during mid-Summer. Cold season grasses on the other hand tend to grow fast and flower earlier in the season.

Interestingly enough, the difference between these two groups lies in the way they photosynthesize.

Warm season grasses have C4 photosynthesis, wherein the first carbon compound produced during the process has 4 carbons, whereas cool season grasses have C3 photosynthesis, in which a 3-carbon compound is the initial product.

C4 grasses are much more productive in photosynthesis during hot and dry conditions. So just when C3 cool season grasses start to slow down because of the heat of summer, C4 grasses start revving up their engines.

Flowering spike of Schizachyrium scoparium

Two warm season grasses I have are Panicum virgatum 'Northwind', which I purchased a couple months back, and a specimen of  Schizachyrium scoparium (Little Bluestem), which is native to this area, and which I had obtained last year.

I've always liked S. scoparium, ever since I saw fields of this species on a trip to New Hampshire, and its inflorescence is quite distinctive and beautiful to my eyes.

Spikelets of Panicum virgatum 'Northwind';

The P. virgatum cultivar has also become a favorite of mine, with its erect and tight form and blue green leaves. Its spikelets are quite tiny, and when I photographed them a few days back, they had yet to mature. But I am already looking forward with anticipation to the full panicles maturing, their branches opening up like some botanical umbrella.

Go, go C4s! ;-)

Oplismenus undulatifolius at Patapsco Valley State Park (Avalon Area)

The new invader was first discovered in 1996 in Patapsco State Park in Maryland (Peterson et al, 1999). 15 years later, it had spread to thousand of acres in Maryland, Virginia, and even one spot in Pennsylvania. But its origin in the USA was at this park, and on the way home from Shenandoah we visited it for a very short while to see first hand its presence in the park.

We entered the Cascade Falls Trail using the Cascade Trail North Carpark, and a short walk of around 15 min quickly took us to one of the falls. At the falls itself I was interested in seeing a single plant growing from between two smooth rocks in front of the waterfall, and nearby was a young colony at the base of a tree.

A single specimen peeking out from rocks near the waterfall

On the trail itself I encountered a few colonies of the species, and what was interesting was that quite a few of the specimens in the area had leaf damage. Although at first I thought this was from too much light or from some herbicide, Dr. Vanessa Beauchamp said that it was most likely leafminers that caused it. Indeed, it seems a few insects like the leafhopper Tylozygus geometricus and wood midges (Lestremiinae spp) can also cause damage.

Damage from leaf miners

The damaged grasses though were confined to one area of the trail, and many of the other specimens that I saw were fine.

Clumps of O. undulatifolius along Cascade Falls Trail, with some of the individuals showing leaf damage.

I was also surprised to discover masses of the species intermixed with other weeds on the slopes of the trail area which can be viewed only from across from the parking lot. I had to use my telephoto lens to get close enough to identity the grass.

Masses of O. undulatifolius on the side of a small hill, I used a telephoto lens to view it.

All in all I enjoyed the very short stop at Patapsco Valley State Park, and wished I had more time to explore more of the area. Perhaps one day when we pass by again.

Literature Cited

Peterson, P.M., E.E. Terrell, E.C. Uebel, C.A. Davis, H. Scholz, and R.J. Soreng. 1999. (Scientific Note) Oplismenus hirtellus subspecies undulatifolius, A new record for North America. Castanea 64:201-202.

Ornamental grasses take center stage at the Virginia House

I visited Shrine Mont in Orkney Springs, VA during a survey for the new invasive Oplismenus undulatifolius. While there, I marveled at a 4 story building that seemed the embodiment of some antebellum fantasy.

In fact, the building was built in 1847 and restored in 1987, after it had been purchased by the Shrine Mont in 1979. It now functions as the conference center for the retreat center, which hosts workshops, conferences, and music festivals, as well as family reunions and vacations, parish weekends , and individual retreats,

The grounds around the building had been designed with simplicity and elegance in mind, and the centerpiece of the large lawn was a round growing space where a huge Miscanthus specimen stood, surrounded by four clumps of Japanese Blood Grass (Imperata cylindrica). Various low growing dicot flowering plants completed the tableau.

I love it when landscapers make major use of ornamental grasses, and the towering Miscanthus and its attendant plants certainly make for an arresting display. Images from a decade back show that the space had more taller non-graminoid flowering plants at the time, and neither the Miscanthus nor the I. cylindrica were present, so this might been a somewhat recent design.

The other interesting thing was the fact they had made use of I. cylindrica, which just so happens to be designated as a Tier 2 noxious weed in that state. This means that it is present in the state and is subject to suppression and eradication efforts, and that its movement is controlled. One wonders what the groundskeepers would think if the plants suddenly reverted to their wild all-green form ;-)

How to identify Oplismenus undulatifolius (Wavyleaf Basketgrass)

I'm not an expert at all in identifying grasses, and in fact I'm quite new at it. But in the case of this new invasive species identification is actually fairly easy so long as you look for certain attributes. And you don't even have to look at ligules!

1. Look for even and regular ripples on the upper leaf surface. This is I think one of the most characteristic feature of this grass.

2. Check the stems for hairiness. This species is quite hairy, and the hairs are visible to the naked eye. This is also one way to distinguish this species from native Oplismenus, which are much less hairy.

3. When looking at a riot of understory plants, look for specimens that tend to sprawl on the ground and whose alternate leaves are all on the same plane. The leaf tips are also quite long and sharp.

Easy, right? Now see whether you can spot this species in the image below.

See them?

Here are some specimens in that pic ;-)

In search of a new forest invasive : Oplismenus undulatifolius (Wavyleaf Basketgrass)

The Wildflower Trail is a 1.3 km paved trail that follows along the route Gen. Stonewall Jackson took when he marched from the Shenandoah Valley to Fredericksburg through New Market, Virginia.

I had some time in between hikes in Shenandoah and so I had decided to visit this very easy trail in search of one of the newest invasive grasses in the country.

Trudging deeper into the woods

Oplismenus undulatifolius (Wavyleaf Basketgrass) was first discovered in the 1990s in Patapsco State Park in Maryland (Peterson et al, 1999). It is a very shade-tolerant perennial grass that reputedly can crowd out competitors and cover the dark understory of forests. It is currently found only in Maryland, Virginia, West Virginia, and Pennsylvania (one treated colony), and some specimens have been found as far west as the Shenandoah area (EDDSMaps, 2020). Its ability to thrive in as low as 2-11 mols m(-2) day(-1) means it can occupy niches where even the dreaded Microstegium vimineum (Stiltgrass) has trouble dominating.

It should be noted that a native species of this genus (Oplismenus hirtellus and perhaps others) is also found in the United States, mostly in the Southeastern part of the country, and should not be confused with this non-native invader. They can be distinguished by the fact O. undulatifolius is conspicuously hairier and has white flowers, whereas O. hirtellus has purplish or reddish flowers.

The fallen logs

The entrance to the Wildflower Trail is  pretty unobtrusive, and I would have easily missed it if I had not been using google maps to plot my way. But when I cruised into the rather large parking lot I saw that people still knew about it, because there were 5 other cars parked.

The surprise find

Heartened by the presence of other  hikers, I trudged into the trail and made my way deeper into the forest. There were smatterings of M. vimineum along the sides, but none of the other many plants looked like the pictures of O. undulatifolius that I had seen on the web.

Rippled leaves

The trail ended in a circular open space, and I still had not found any evidence of the invasive grass.  Instead of going back to my car in defeat, I decided to press on into the woods, and I slowly made my way forward where the piles of decaying leaves that coated the ground was less thick.

Hairy stems

When I spied two large fallen logs I carefully leveled myself up onto one and peered into the shadowy depression formed by their intersection. Imagine the surprise I felt when I spotted a few leaves that seemed to have the rippled surface so characteristic of O. undulatifolius!

The grass was intermixed with masses of M. vimineum, as well as a few other plants, and a careful search of my surroundings revealed more of the invasive (including near a large clump of stiltgrass), although never in a large enough grouping to merit unusual attention. I even found a very young specimen that even at that small stage had the characteristic rippled leaves. I was able to quickly ID the plants because in addition to the rippled leaves, O. undulatifolius has very hair stems, and its sprawling behavior on the forest floor also helps in the identification.

Mixed in with the stiltgrass

While hiking through trails in nearby Shenandoah National Park, I made it a point to look for the species, although the rapid pace of our hike meant my search was not very comprehensive at all. Nevertheless, O. undulatifolius had been seen in the area, and it is being actively controlled by park management. This is because unlike M. vimineum, which is now ubiquitous, this new invasive is still at that stage where it may be possible to control its spread.

More specimens around the base of a tree

Although it is currently only found in Maryland, Virginia, and small outbreaks in northern West Virginia, there was a chance that it might have spread towards West Virginia from the Shenandoah area, and so when I visited Wolf Gap Recreation Area in Wardenville, WV, I combed the nearby trails and campgrounds for any signs of the species. I also visited Shrine Mont in Orkney Springs, which lies near the border of West Virginia and Virginia. In both cases, I found M. vimineum in abundance, but no sign of the newer invasive.

Two younger individuals

However, the spread of O. undulatifolius to other states is something that I believe is inevitable. Vanessa Beauchamp, an invasive plant ecologist in Maryland who specializes in the species and fought valiantly to contain its spread, found that its sticky seeds stuck easily not only to people's pants legs, but also to passing animals like pet dogs. During one test, she discovered that a pet dog who run for 30 seconds in a field of O. undulatifolius managed to pick up an amazing 2000 seeds.

Given such fecundity, and coupled to the perennial lifestyle of the species and its ability to thrive in deep forest canopies, it is probably only a matter of time before it threatens major parts of the northeastern half of the USA.

A very young specimen already has the characteristic rippled leaves

For more on O. undulatifolius on this site, click here.

Literature Cited

EDDMapS. 2020. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed July 25, 2020.

Peterson, P.M., E.E. Terrell, E.C. Uebel, C.A. Davis, H. Scholz, and R.J. Soreng. 1999. (Scientific Note) Oplismenus hirtellus subspecies undulatifolius, A new record for North America. Castanea 64:201-202.

Merrill Creek Reservoir Trails and the lowdown on Microstegium vimineum (Stiltgrass)

A carpet of Microstegium vimineum covers the forest floor in Merrill Creek Reservoir

We hiked two trails in the Merrill Creek Reservoir in Harmony, NJ during the July 4th holiday. We traversed the entire length of the Shoreline Trail (blue) along the southeastern flank of the area, then spent an hour or more on the northwestern part of the Perimeter Trail (black).

There were very few hikers in either trail, and the Shoreline Trail in particular seemed relatively unmaintained, with grass frequently on the ground and understory vegetation crowding hikers from the sides. Although there were some nice views of the lake at certain spots, on the whole the tight narrow paths in some parts of the trails made for uneasy going, and we later found out my wife had a deer tick biting her shoulder!

The distinctive bamboo-like leaves of M. vimineum, with the distinctive line of silvery hairs along the midline

The hike did make me think about one of the worst invasive plants spreading in our forests right now.

Microstegium vimineum (or Stiltgrass) has small bamboo-like leaves with a distinctive silvery line along the midline. It is a low-growing grass species that has been pushing aside native vegetation in shady forested areas, and when people talk about this invasive, one sometimes has visions of immense swaths of forest understory clothed in its delicate green blades. Instead of a varied mix of other grasses and low herbaceous plants, one sees a monoculture that has strangled other competitors and holds sway over vast tracts of parkland and virgin woods.

Microstegium vimineum lines a hiking trail  in Merrill Creek Reservoir

I hike a lot in New Jersey and the surrounding states, and in my walks I have found that the reality is of course somewhat different than the visions of botanical Armageddon that some may have.

It's true that there are large areas which have undulating carpets of stiltgrass covering the forest floor, and there are many more cases where the hiking paths are lined on both sides by this invasive. But for much of the time M. vimineum is represented by perhaps only a few specimens whose small forms are lost in the riotous tangle of other understory vegetation.

This of course does not mean that we should become lax about protecting the biodiversity of our parks and forests. From all indications this invasive is expanding its range, and just because it does not completely dominate entire forest understories right now does not mean it won't do so in the near future.

The spread of this invasive is aided partly by mechanical means, including through the clothing of passing hikers. So if you encounter this species during one of your hikes in the woods, be sure not to inadvertently contribute to its spread by brushing against the plants.

The rhizome of Imperata cylindrica (Japanese Blood Grass)

I was transplanting some Imperata cylindrica from one container to another, and as always I stopped to look at its rhizomes.

Rhizomes are underground stems, and the green form Cogon grass forms extensive networks that may comprise up to 60% of the total mass of the plant! This very low shoot to rhizome/root ratio means that damage to the above ground shoots through fire or cutting does not kill the plant.

The rhizomes also allow colonies to quickly expand, with new stems and roots developing in the nodes of the rapidly spreading rhizomes. I am always fascinated to see new culms popping out of the ground far from the main clump of I. cylindrica.

The sharp tipped rhizomes have also been implicated in stabbing surrounding structures, whether the rhizomes or roots of competing plants, or its own underground rhizomes. The ability of the rhizomes to do this is because the tip of the rhizome is surrounded by continuously growing leafy bracts that have amazingly sharp tips. The tips can draw blood when touched too hard, and they allow the rhizomes to burrow through hard ground and even break through plastic tarp covering the soil!

References:

Characteristics of Cogon Grass Rhizomes and its Perforation of a Maiden Cane Rhizome.
Muchovej, J. J.; Onokpise, O. U.; Bambo, S. K. // International Journal of Botany; 2009, Vol. 5 Issue 4, p314