Saturday, November 27, 2021

The Vexing Problem of Invasive Ornamental Grasses

Cortaderia  selloana in Virginia 

The use of ornamental grasses has been growing rapidly since the 1970s, when Cortaderia selloana (pampas grass) and Festuca glauca (blue fescue) were the only well known ornamental grasses sold in West Coast retail stores.

It's a different situation today, with ornamental grasses gracing many residential and commercial areas, and even having their own sections in gardening stores.  

But look closely at the selection in many stores and you'll come to realize that many (if not most) of the ornamental grasses are not native to the region in which they are being sold.

Huge Cortaderia selloana on sidewalks in Virginia 

Unfortunately, many people select ornamental  grasses without any consideration about their potential for harming the environment, and  the horticultural industry itself may exacerbate  the problem by continuing to sell plants that have been proven to be invasive. This lack of awareness extends to even reputable botanical gardens and arboretum, and I have repeatedly seen some institutions make heavy use of ornamental grasses like Miscanthus sinensis. Granted, these non-native grasses are often beautiful, but this dependence on such cultivars creates problems due to the potential invasiveness of the species. 

Escaped Cortaderia selloana in Florida

It's not all black and white though. What may be invasive in one region, might be relatively benign in another clime. For example, Imperata cylindrica is one of the most invasive grass in many subtropical and tropical areas in the world, but a red  cultivar (called Japanese Blood Grass)  is relatively harmless in colder areas, even though it can allegedly revert to an all-green invasive form when grown in a more suitable climate.

Large Miscanthus sinensis in parking lot of suburban strip mall in NJ

However, a species that may at first seem non-invasive can become invasive over time. This might have been the case with the popular  Cortaderia selloana (pampas grass) from South America.

Escaped Miscanthus sinensis at forest edge in NJ

This species became very popular in the late 19th century, with society becoming enamored of the large pure white inflorescence and using it almost everywhere. At one point, half a million of the plumes were being sold yearly. But for decades, the invasive nature of C. selloana seems to have been overshadowed by a close relative. C. jubata. In fact, even in the 1970s, researchers reported most of the infestations they found were of C. jubata, and non-cultivated C. selloana did not exist far from human habitation. This seems to have changed by the 1990s, when new surveys showed that C. selloana had become the more invasive of the two, with outcrossing populations found in many different native habitats. Even the morphology of these populations had changed, with the pure white plumes becoming darker.

Arundo donax in an arboretum in NJ

There are sterile options when it comes to non-native ornamental  grasses, including hybrids of M. sinensis. These can be a way out of the trap of desiring particular grasses that have the potential to be invasive, although consumers have to do their research  before buying such species.

In the end, there are several possible solutions to the problem of invasive  ornamental  grasses:

  1. Make it illegal for the retail industry to sell invasive species, and enforce the law.

  2. If possible, sell sterile cultivars of any non-native species.

  3. Continue to inform people about the problems associated with non-native ornamentals, even those that do not seem to be currently invasive.

  4. Promote the use of native ornamental grasses, such as Panicum virgatum, Schizachyrium scoparium, and Andropogon gerardii cultivars. Emphasize not only the environmental reasons for using these, but also their beauty and adaptability.
Only through the rigorous implementation of all these will we be able to make sure we continue to protect the integrity and beauty of our native habitats.

Cortaderia selloana in North Carolina parking lots


Lambrinos, JG (2004). A tale of two invaders. The dynamic history of pampas grass and jubata grass in California. Cal-IPC News. Vol. 12, Nos. 3/4

Friday, November 26, 2021

The Perfect Obsession

New Mexico

I used to pine for the tropics. 

I missed the warm weather and amazing biological diversity that was a common part of my life when I was younger. Many of the things I was passionate about were nowhere to be seen in temperate areas, which was where I found myself the last few decades due to work or family. Thus, I usually had to wait for vacations and trips to find those plants and animals that had grabbed my interest. 

There are temperate aroids here in the East Coast, but none of the large exotic Meconostigma that I specialized in. There are no large banyan trees with their amazing buttresses and surreal aerial roots, nor exotic insects or predatory stomatopods.

It came to a point where I was planning vacations based solely on whether I could spend some time looking for and studying my passion at the time.

New Hampshire

But this all changed when I discovered my fascination with the Poaceae.

Grasses can be found quite literally almost everywhere. They inhabit every continent, including Antartica, and can be found in every type of habitat and ecosystem on Earth. And not just in small ones and twos either, but in many cases in numberless masses that blanket entire fields and hillsides.


So now I can indulge in my fascination with this plant family almost 365 days of the year, although winter does bring with it the near cessation of growth of all vegetation in these norther climes. No longer do I need to miss the beauty of boreal and temperate landscapes because of my near obsession with warmer travels.

I have at last found a perfect obsession, one which rewards my curiosity and desire for learning and discovery each and every day.


Tuesday, November 23, 2021

The Bad-Ass Bamboo Forest in Shang-Chi

Shang-Chi's parents meet with the Bamboo Forest as backdrop for their fight

I just watched the new Marvel movie Shang-Chi on Disney Plus, and I have to say I enjoyed it a lot.

It was funny, the cast was personable and relatable, and the special effects were fantastic. The movie has a 92% rating at, and it broke several box office records during its release.

But two scenes in particular made me really like the movie.

The mother of Shang-Chi comes from a village called Ta Lo, which is filled with magical beasts from Chinese folklore. This village is guarded by a bamboo forest, which forms a beautiful backdrop for a fight scene between the hero's parents when they first meet.

The bamboo in the forest also can move, and they have a penchant for wanting to squash intruders who try to find Ta Lo.

This awesome behavior is in full view in two different car scenes, where the maze-like forest opens up in front of rushing cars, only to close violently behind them. Anyone not fast enough to outwit and outrun the closing forest is smashed into bits and "eaten".

Fiction books and movies are replete with hostile plants, but this variation on the theme was entertaining and unique, and I highly recommend the movie to everyone. Enjoy!

Official Trailer:

Saturday, November 13, 2021

Wild on Ornamental Switchgrass (Panicum virgatum)

I admit I am a sucker for Panicum virgatum ornamental grasses.

I think it all started when I read The Obsessive Neurotic Gardener, a gardening blog whose author was particularly enamored of ornamental grasses.

He introduced me to a cultivar called P. virgatum 'Northwind', which not only has metallic green leaves, but looked quite stunning because it grew straight up and did not tend to flop after awhile. 

P, virgatum "Northwind"
I bought  one of these 2 years ago and it was indeed a beauty, with seemingly iridescent blue green  leaves that stood straight as an arrow.  This cultivar was introduced by  Roy Diblik of Northwind Perennial Farm, Lake Geneva, WI, and in 2014 it won the Perennial Plant of the Year, awarded by the Perennial Plant Association. I have seen it stand up to very strong winds, the thin blades not bending to the force of the storm.

"Thundercloud" to the left, and "Northwind" to the right

I also bought one of the crosses made using P. virgatum " Northwind" (with the tall cultivar P. virgatum "Cloud Nine") by Hoffman Nurseries, one of the premier ornamental grass suppliers here in the USA. 

P. virgatum "Thundercloud" attains a height of about 2.5 meters, with bluish leaves and the usual airy cloud of panicles. I got it this Spring, and it shot up to 1.3 meters this year (1.5 m with the panicles), easily overshadowing the more diminutive "Northwind". I can't wait to see how it does next year, although I have some concerns about the availability of growing space!

P. virgatum during winter

The largest ornamental grasses in our neighborhood are various cultivars of the non-native Miscanthus  sinensis, although one home seems to have a group of Saccharum ravennae as an unusual addition to their front lawn. But native ornamental grasses like P. virgatum are just as attractive and are certainly just as hardy, and I hope their popularity continues to grow.

Saccharum ravennae

Monday, November 8, 2021

How Lawns Might Affect the Perception of Prairies

Many Americans hate lawns, for various reasons. 

Perhaps their belief is based on the notion that lawns are bad for the environment, whether it's because of the chemical runoff inevitably created by their maintenance, the inordinate waste of water to sustain them, or the lack of biodiversity and havens for pollinators. But many other people, perhaps the majority, are either supportive of lawns, or at least apathetic to the social and even legal requirements that homes should maintain a cut clean lawn on their front yards.

I've sometimes wondered whether such viewpoints could be a factor in the way this one segment of society might view prairies. In this case, lawns may have a negative impact because the ideal and perfect lawn in their minds is the complete antithesis of a prairie. Lawns are  basically  human-maintained prairies where all the multitudes of plant and animal species have been stripped away and discarded, leaving behind just a few desirable grasses.

When they see a prairie, this notion of an idealized lawn could (even if subconsciously) blind them to the truth. Instead of seeing the amazing biological diversity contributed by the many forbs and other plants, they see "weeds"; instead of marveling at the animals that make the prairie their home and add to the wonderful complexity of food webs, they see "pests"; and instead of being awed by the tall grasses they see an unmown landscape.

What a tragedy, if this is the case!