Sunday, September 24, 2023

Guardians of the Weed Field

A Lovecraftian Field of Cogongrass

This was written in March of 1986 for a paper, but the events in it happened almost a decade earlier, in the late 1970s. The weed field in the story was dominated by the usual dominant species in the Philippines, probably Imperata cylindrica (cogongrass) and Saccharum spontaneum (wild sugarcane).

I remember the day they burned the field down.

I was a fifth-grader then, perhaps only 10 years of age, and on my way to my school's elementary school library. Lunchtime had just began, and for the next hour or so I would eagerly wade through a Hardy Boys or Nancy Drew mystery; I had not yet discovered science fiction books (in the guise of the ever popular Star Trek series) and the lives of those teenage detectives seemed to me the height of adventure. It was while thinking of these same detectives that I noticed  faint wisps of smoke rising  from beyond one of the school's  many playgrounds.

To one side of my school there lay a wild tangle of rank grasses and thorny plants - a virtual no-man's land that was part of the school property. This weed field extended from the school's side and half way to the horizon and was some 50 meters across, which made it one really gigantic monster to my over-active 5th grade imagination.

Saccharum spontaneum, Philippines

Nestled between this field and the school was a small area that had been cleared of the meters high weeds, and here we students did our gardening; we toiled and troubled over our sickly-looking vegetable plants, all the while wondering about the "jungle" that nearly surrounded us and the positively gruesome creatures that we knew lived within it. Like normal pre-teens however, the thought of what lay concealed within that wild land did not repulse us but drew us towards it, and we once dared each other to walk into the field and stay there for an hour or so, a peso to the fellow who came out whole and alive. Finally, one or two takers walked into the field when our Practical Arts teacher was conveniently busy with something else, but they were soon dragged back by this enraged gentleman (who had threatened us all with F grades if we failed to reveal the whereabouts of our missing classmates) and sent to the principal. Needless to say, we never tried that stunt again. 

Imperata cylindrica, Philippines, from Amazing Lingsat.

Now I could see smoke rising from the weed field; it came from half a dozen or so fires that raged throughout the land. Plants that were once so tall and proud now became blackened ash that filled the air and rained all over the side of the school nearest to the field. A growing crowd of excited students watched as men from the school started new fires in an effort to hasten the weed field's demise, their tiny figures barely visible in the distance as clouds of ash and smoke rolled in from the burning field to cover a nearby playground. I thought at first that the fires would spread to the school proper, but the men obviously knew what they were doing and somehow controlled its spread.

I stayed watching for a while longer, then continued on my way to the library. The afternoon passed, and it was soon time to go home. But my school bus was late (as usual) and so I decided to see what had happened to the weed field.

Playing field in school. From D. Gamboa and E. Nacion.

While I was busy slaving away in my hot, stuffy classroom, the workmen had done their work - more than half of the field had been converted to ash. The weed field looked fearsome and awe-inspiring no more; in fact, it looked downright pitiful that fateful afternoon - a victim of my school's expansionist policies. I learned later that a school chapel would be built over the ashes of the field.

I found the weed field's creatures that day. They were stored in glass jars filled with formaldehyde, their scaled bodies coiled tightly in death. The jars stood like brooding sentinels on open wooden shelves. There were dozens and dozens of the slain creatures, from foot-long green snakes to pythons reaching three meters in length. They had escaped the fires only to be caught and killed by the ever-vigilant workers. 

I remember feeling sorry for these misunderstood "monsters", who we children had feared and perhaps even hated for so long. In death, they did not seem menacing even to my young eyes, but instead seemed so pitiful. They were the guardians of the weed field and they had guarded it well for so long; and when their home died, they had died loyally with it.

Monday, September 18, 2023

Second update on the rapid expansion of an invasive grass in Florida

Hillside with cogon grass. From Amazing Lingsat

The previous 2 posts on this topic:

Update on the rapid expansion of an invasive grass (December 30, 2021)

Rapid expansion of an invasive grass as viewed using Google StreetView (April 4, 2021)

About 20 months after the last update (December 30, 2021), I again visited the same location and checked on the pace of expansion of the Imperata cylindrica cluster.

The cogon grass cluster had been expanding at a rate of 0.6 meters per month to one side, and during the last check, it had moved 6 meters to the west (left) of a green optic cable marker (see pic below).

When I visited yesterday, the cluster had expanded laterally another 6 meters before encountering a large low lying tree (see pic below).

Cogon has continued lateral expansion all the way to tree on west (left). September, 2023

The cogon ramets had crowded to the right of the crown of the low lying tree, but has not yet been able to bridge the shadow gap and cross to the other side.

However, I found isolated ramets huddling under the tree's shadow, with the one furthest west about 3 meters in from the crown edge. In addition, the cogon cluster is at the same time growing around the tree from behind. The result of these two activities means that sooner or later, the cogon will make its way to the unshadowed west side of the tree. at which point it should again commence its rapid lateral movement.

Cogon slogging under the tree's shadow towards the other side. September 2023.

The expansion rate of 0.6-0.7 meters per month that I had calculated in previous posts was based on an unshaded environment. It's been 20 months since I checked in Dec 2021, and in that time, the cluster has moved around 9 meters sideways, which comes out to 0.45 meters per month. This is noticeably slower than before, but obviously understandable given the shaded territory that it is trying to cross.

An interesting side topic is the ability of the species to traverse shaded environments. Although there are some indications that cogon grass is able to tolerate some shading, the presence of ramets deep into the shade of the tree might be explained by something more interesting.

As a rhizomatous species, cogon grass may have clonal integration. That is, researchers have found that clusters of interconnected ramets have attributes that cannot be found in non-clonal species. Not only does information flow between the members of the genet, but nutrients and water can be translocated throughout the entire network of ramets. This ability to actively and deliberately move information and other materials allows these clonal grasses to withstand stresses in heterogeneous environments that separated individual plants cannot. 

Thus in this case, the ramets under the crown of the tree might be sustained by photosynthates flowing to it from the unshaded and larger clones. 

More information on clonal integration is discussed here:


I've been rather lax in checking up on this fascinating invasion recently (has 20 months gone already!!), but in future I'll try to update it every 6 months or so. 

Thursday, September 14, 2023

Life in the Cracks Part Deux (Vertical Edition)

The very first article I posted was in July 2019, when I marveled over all the varied life that existed around us without being noticed.

In that post, I highlighted Digitaria spp weeds that had sprouted up from the cracks in the parking lot of an office complex.

Life In the Cracks

I was reminded of this again while walking around a park in Broomfield, CO last month, and I noticed a wayward individual grass that had somehow germinated from an extremely narrow vertical crack going up the side of a bridge.

The base of the culm comes straight out of the narrow crack.

There were no other vegetation at all in the long crack, and given that it hadn't rained in a bit, I had to wonder how the specimen was surviving at all. The other question that sprung to my mind was how it got there in the first place, and the most likely explanation was that a wind blown seed had fond its way into the crack, and had been lucky enough to take root before it could be dislodged.

It was a Setaria sp (Setaria viridis?), members of which seem to have a proficiency when it comes to such an epiphytic lifestyle. I have seen members of this genus proliferating along walls in New Jersey as well, although none of those were in the same precarious situation as this lone Broomfield individual.

Flowerhead of the specimen

To most people, such minor miracles as this are not even noticed, or acknowledged. At most their eyes might hover fleetingly over the lone survivor, then dismiss it as just another weed and continue on.

But when I first saw this, I was amazed. Life, it seems, will always find a way. It will grow and exist if there is any way at all to do so, no matter how unusual or surprising its method. Life is persistent; it is dogged and stubborn. It will turn up in the most unexpected of places, and surprise us.

I hope I never get tired of having such feelings of amazement at the wonder of life.

ps. as an aside, the ability of members of the Poaceae to survive in what seemingly are epiphytic conditions again highlights the question of why the family does not have more real epiphytes, like the members of the Orchid and Bromeliad families. There are only a grand total of perhaps 2 grasses that are considered truly epiphytic, out of a membership of around 12,000 species. Why have grasses, which are so dominant in many other places, failed to capitalize on this niche?

The answer to the question seems to be tied to the fact that the Poaceae are mainly wind pollinated, and that such a mechanism is not optimal in the wet, humid and closed environments that are favored by true epiphytes. For more on this topic, click below:

Calling all orchid-wannabees: Where are the epiphytic grasses???

Sunday, September 10, 2023

A Short History of Ornamental Grasses

World's Fair Pavilion in Forest Park, in St. Louis

Ornamental non-bamboo grasses have become such a ubiquitous feature of suburban and urban landscapes nowadays, that it might surprise some people that their widespread use is a relatively new phenomenon here in the USA.

This was brought home to me after I visited the World's Fair Pavilion in Forest Park, St. Louis last week.

The park itself is amazingly large, but what interested me most was a building that was surrounded by large stands of beautiful ornamental grasses. This World's Fair Pavilion was built in 1909 from proceeds of the World's Fair that was held in 1904. It's built on top of a hill and is surrounded by a large expanse of lawn and other plants.

Gigantic Panicum virgatum in Forest Park, St. Louis

The largest Panicum virgatum specimens I have ever seen in masses graced both sides of the area in front of the pavilion. There were also stands of Miscanthus sinensis, as well as the usual stately Calamagrostis. These ornamental grasses dominate the landscape today, but pictures of the same pavilion from the 1930s showed no signs of the stately and graceful grasses. Instead, shrubs and bushes and trees were the norm (see image below).

The pavilion in the 1930s. From the Missouri Historical Society. Note the lack of ornamental grasses.

The drastic change in the landscaping is significant. Although the use of bamboo for landscape decoration was popular even during ancient times, ornamental non-bamboo grasses did not enjoy the same popularity. However, during the 1930s, the renowned  German nurseryman, Karl Foerster pushed for their use in Germany and Europe. He collected grass seeds and plants from all over the world, and after cultivating them in his nurseries he introduced them to the market.

Calamagrostis to the left, Panicum virgatum to the right. In Forest Park, St. Louis

Among the many plants he introduced, perhaps his most famous creation is the outstanding ornamental grass Calamagrostis × acutiflora 'Karl Foerster', which he released to the market in 1950 as a natural hybrid of C. epigejos (native to Europe, Asia and Africa) and C. arundinacea (native to Eurasia, China and India).

Calamagrostis in background, Cenchrus setaceus in foreground, in Colorado

This rise in the use of ornamental grasses in Europe was not mirrored in the USA until much later, but various growers were instrumental in pushing for this new paradigm.

In the early 1960s, Kurt Bluemel began the introduction of ornamental grasses into America through his nursery in Maryland, called Kurt Bluemel Inc. Educated in Germany and Switzerland, Bluemel was passionate about grasses, and by the time he passed away decades later, he was well known as Der Gras K├Ânig, the Grass King. 

Kurt Bluemel. From Baltimore Sun.

He is said to have carried his first grass specimens in his luggage when he came to America, and his collaboration with Wolfgang Oehme, a German-born landscape architect based in Towson, was highly influential in creating a growing appreciation for ornamental grasses in the country. Some of his notable works include creating the savannas at Disney World's Animal Kingdom, and Busch Gardens. 

Panicum virgatum

By the 1980s, the momentum behind ornamental grasses had finally reached a crux, and an influx of growers finally pushed it into the mainstream. In 1986, John and Jill Hoffman established the Hoffman Nursery in North Carolina, which specialized in ornamental grasses. 

John Hoffman. From Hoffman Nursery.

John's interest in ornamental grasses was stoked during a visit to Germany, where he met the plant breeder Ernst Pagels. Pagels was an enthusiastic supporter of grass-filled gardens, and this along with the support of his mentor,  J.C. Raulston at North Carolina State University, fueled his passion. Today, Hoffman Nursery is one of the largest suppliers of ornamental and native grasses in the country.

Miscanthus sinensis

The trend towards landscaping with grasses then moved from the East Coast to the West Coast through the efforts of people like horticulturalist John Greenlee. In order to complete an oak savanna project in California in the 1980s, he travelled to Kurt Bluemel's Nursery in Maryland, where he was astounded by the hundreds of varieties of ornamental grasses that were on display. He ended up trucking a load of the grasses in a tractor trailer from Maryland to California, and after a stint in Brazil with the renowned landscape architect Roberto Burle Marx (who is also held in high esteem in the aroid community), he finally opened the first ornamental grass nursery in the West Coast.

John Greenlee. From Greenlee Meadow Collection.

Fast forward to today, when people routinely use ornamental grasses both in residential and commercial landscaping. And although many of the varieties used are the showy exotics (such as Miscanthus sinensis and Cenchrus setaceus), the use of native grasses as ornamentals (such as Trypsacum dactyloides in Florida, and Bouteloua gracilis in Colorado) is also widespread.

Bouteloua gracilis in Colorado

Meanwhile, new varieties and species continue to be introduced into the market. Not only do they contribute linear structure to a design, but their ease of maintenance, resistance to herbivores like deer, and their ability to impart movement to an otherwise static landscape, make ornamental grasses perfect components for any project.

Looking out from the pavilion in Forest Park, St. Louis. White flowerheads are Miscanthus sinensis cultivars