Psammophyte Beach Bum in a Barren Land: Sporobolus virginicus in Paracas, Peru

The area around the beach town of Paracas in Peru is pure desert, a desolate land with nary a plant beyond those weedy and cultivated critters that settled into the few human settlements in the region.

But close to the sea, various native plants clung to life against the all encompassing dryness. Precipitation is under 1 cm per year in the region (!), and the few areas with water are an oasis that attracts life.

One of the few plants that was not deliberately planted was Sporobolus virginicus, which thrived in large clusters next to the beach in town. It is called Seashore Dropseed in the USA.

This species is found all over the Caribbean and American coastal mainland, and is an extreme halophyte. That is, it is able to tolerate high salt concentrations, something that is advantageous in the saltwater drenched beaches where it loves to bum around. Some populations of this species can tolerate up to 1.5 M NaCl, which is 3 times the salt concentration of sea water!

In addition, the species is a psammophyte, which simply means that it can thrive in areas that are sandy and often unstable. This again makes it suitable for the changeable landscape of coastal beaches.

The grass itself is a tough looking critter, with stiff pointy leaves and a seemingly aggressive manner. Even its flowerheads are no nonsense structures bereft of any extraneous adornments. If this is a beach bum, then it's one that you don't want to tangle with. In fact, I saw one Paracas cluster sending ramets deep into  the midst of a neighboring plant, an act that seemed quite hostile. But appearances can be deceiving, and I have not seen any references that indicate the species has become invasive, or that it is even a particularly aggressive species in all the many places that you can find it.

It is also relatively easy to identify in beach settings, although one needs to see the flowerheads to differentiate it quickly from something like Paspalum vaginatum (which has the more typical Paspalum inflorescence). So the next time you are walking along a beach and see clusters of S. virginicus, think to yourself and marvel at the adaptability and tenaciousness of this cosmopolitan beach bum.

Rogue's Gallery of Exotic Grasses in Sacramento, CA

I was visiting a park yesterday in Sacramento (California, USA), and I chanced upon a scene that tickled my fancy.

Exotic and invasive grasses are not a rare sight in the state, especially since the so-called Golden Hills of the state are the direct result of the introduction of alien species - more on that in a later article. But by a fortuitous coincidence I managed to take a single photograph that had quite a few of the more infamous exotic grasses in it. 

 Included in the image is Taeniatherum caput-medusae, Aegilops triuncialis, Bromus diandrus, and Avena barbata/fatua. Click on the image to expand and try to see whether you can spot examples of each!

A couple of the specimens in the photograph are actually new to me. One was the beautiful (but invasive) Bromus diandrus., which is much larger than B. tectorum (cheatgrass).

 

Bromus diandrus

The other is Aegilops triuncialis, which is commonly called barbed goatgrass in the USA. 

Aegilops triuncialis

As an aside, in addition to seeing Aegilops spp for the first time ever, I also saw my first specimens of Bromus madritensis (which has the common name Red Brome here in the USA). This species has an attractive inflorescence, but has proven to be quite invasive in desert shrub habitats and grasslands.

Bromus madritensis

Bromus madritensis

The Viking Syndrome: Why Grasslands (and Grasses) Became Wildly Successful

The open spaces, the open grasslands. Nothing could be better.

The overwhelming success of the Poaceae is not simply because of their well known habit of growing from the base, unlike many other plants. It is also because they exhibit traits that when taken together, researchers have termed the "Viking Syndrome", in honor of the ancient group that ranged far and wide, colonized many places, and had profound effects in areas where they landed.

One of the grasses I saw as I first stepped into the streets of Lima, Peru last month was a species that I had seen many times in many different places. There was no mistaking the distinctive digitate inflorescence, nor the wiry stoloniferous habit that was one factor that allowed the grass to become a fearsome competitor and so valuable to turf grass managers. I had seen the same species in New Jersey, in Florida, in several Caribbean Islands, and even in the Philippines. It was the common Cynodon dactylon (called Bermuda grass in the USA), and its success is one that is repeated time and time again in the Poaceae.

Cynodon dactylon in Peru

The discovery of this species in Peru was not even a surprise to me, because I have grown accustomed to seeing grass species that are extremely cosmopolitan in their distribution.

In an earlier article, I had summarized some of the reasons why grasses can be considered the most successful plant family in the world, even not taking into account their economic importance to humanity (e.g. rice, wheat, maize/corn, etc). 

Grasses are only the fifth most species-rich angiosperm family with about 12,000 species (Clayton et al., 2015). And yet ecologically, grasses are by far the most dominant plant family. Areas dominated by grasses cover up to 43% of the surface of the world (Gibson, 2009), and they are found in almost every ecological habitat, including Antarctica. Up to 37% of the land area of the USA is dominated by grasses! Entire ecosystems of animals and other plants depend on grasses for their continued health and existence.

In fact, although grasses account for only 3% of plant species on Earth, grass-dominated landscapes contribute 33% of global primary productivity, the amount of CO2 removed from the atmosphere every year to fuel photosynthesis (Beer et al., 2010).

The overwhelming success of the Poaceae is not simply because of their well known habit of growing from the base, unlike many other plants. It is also because they exhibit a suite of invasive traits that when taken together, researchers have termed the "Viking Syndrome," in honor of the ancient group that ranged far and wide, colonized many places, and had profound effects in areas where they landed (Linder et al, 2018). 

Specifically, grasses have:

1. Efficient dispersal, 
2. Rapid population growth, 
3. Environmental flexibility 
4. Flexible growth forms and phenotypic plasticity
5. The ability to transform environments to benefit themselves

It is this combination of invasive traits that have allowed grasses to become the most successful plant family in the world today.

1. Efficient Dispersal

Grasses certainly are able to disperse far and wide. The method of dispersal after pollination varies among species, but include wind dispersal (anemochory), dispersal via animal coats

(epizoochory), and dispersal after ingestion by an animal (endozoochory). The ability of grass species to be efficiently dispersed is almost everywhere in evidence. 

For example, the dune grass Leymus arenarius was one of only 4 plants to appear during the first decade after the formation of the volcanic island of Surtsey in 1963 (Magnusson et al, 2014). Some grass species like Phragmites australis are also hailed as being perhaps the most widely distributed angiosperm in the world, with a range that extends from 70 degrees N to the tropics (Holm et al, 1977). 

The unit of dispersal is the inflorescence in whole or part. This "diaspore" includes the basic unit of the grass flowers, which are the spikelets. In many grasses these are frequently tiny and lend themselves to easy dispersal, but beyond that grass spikelets can show various modifications that enable them to be carried far and wide. The most common have long awns that help in wind dispersal, but some Cenchrus spp have sharp barbed "thorns" that can easily catch on animal fur or clothing.

The deadly spines of Cenchrus sp

In some others like Oplismenus undulatifolius the awns exude sticky droplets of liquid which can also adhere to passing traffic. Studies have found that a dog running through this grass could pick up 12000 or more seeds on its fur! People are also used as vehicles for dispersal, with one study showing that around 800 seeds adhered to fleece within 30 seconds, while even denim pulled in around 300 seeds within the same timespan (Beauchamp et al, 2013)!

The sticky awns of Oplismenus undulatifolius helps in its dispersaL

2. Rapid Population Growth

The ability to create enormous populations very quickly might be another trait that helps in their invasive success. Such rapid population growth can be the result of shorter generation times and early reproduction. This allows pioneer populations in new habitats to quickly overrun the area, and the shorter generation times also creates more rapid responses to directional selection.

Although no definitive study has been made to compare entire plant families, many grasses have extremely short generations times. For example, the weedy and cosmopolitan Poa annua can flower just six weeks after germination (Cope et al, 2009) . In the same way, the weedy and extremely invasive Bromus tectorum (called cheatgrass in the USA) also can flower within 5 weeks (Meyer et al, 2004).

Interestingly enough, the grass embryo might be one factor that contributes to their reproductive success. Unlike other plants in their order (the Poales), which consist of undifferentiated cells, the embryos of grasses is already differentiated into specialized tissues, including the root, a shoot with leaf initials, and a specialized structure called the scutellum, which digests endosperm and moves it to the rest of the embryo. 

Bromus tectorum can flower within 5 weeks of germination 

3. Environmental Flexibility

The Poaceae as a whole occupy all the environmental niches available to angiosperms. This ability is related to the amazing flexibility of the grasses when it comes to adapting to various environments.

For example, grasses have the ability to survive in the widest range of temperatures among plants, with Deschampsia antartica able to live down to -10 degrees C (with an optimum of 10 degrees), and Dichanthelium thermale able to tolerate up to 65 degrees C in the active geothermal areas of Yellowstone National Park. The evolution of freezing tolerance in the family in particular opened up vast areas of the colder parts of the world to colonization by the grasses.

Another example of the ability of members of the Poaceae to exist in extreme environments is the large number of halophytes in the family. Halophytes are organisms that are very tolerant of high salt concentrations, and the grass family is second only to the Amaranthaceae in the number of species that are halophytes (Moray et al, 2015), with studies indicating that salt tolerance evolved independently at least 70 times in the family (Bennett et al, 2013).

This ability to flourish in a wide range of environments is founded on various traits. As an example, the Poaceae exhibits all 3 different types of photosynthesis (C3, C4, and CAM), an attribute it shares with only 8 other plant families. Since the the type of photosynthesis used by a plant greatly influences where it grows best, this means the Poaceae is capable of existing in innumerable and varied environments. 

The Poaceae also have a strong propensity to readily absorb novel genetic information from  their environment, and incorporate them into their own genome (Hibdige et al, 2021). They do this via a process called Lateral Gene Transfer (LGT), where a species can acquire new adaptive genes and traits from completely different species without any sexual reproduction. Such instances of LGT are an amazing way for a grass to "leap frog" the slower evolutionary pathways and suddenly acquire traits that allow them to survive in extreme and varied environments.

Muhlenbergia capillaris is a salt tolerant dune grass

4. Flexible growth forms and phenotypic plasticity

Grasses have evolved  a variety of growth forms that allow them to adapt to almost any situation or event, whether it be (a) continuous defoliation, such as by herbivores, (b) periodic defoliation, such as in seasonal climates, or (c) competition against other plants such as in forests.

In terms of vertical reach, most grasses are low lying organisms, but some species are tall, and form towering grasslands that reach high above the height of a man (e.g. Saccharum spontaneum grasslands). Bamboos are even taller, and their woody stems allow them to reach the height of mature trees in shaded forests.

In terms of horizontal spread, some grasses are bunch grasses that form tussocks, while others spread horizontally via stolons (above ground horizontal shoots) or rhizomes (below ground horizontal shoots) to form (for example) the typical lawns. This type of growth is controlled mainly by whether the species has intravaginal innovation (new shoots originate from axillary buds within the leaf sheaths) or extravaginal innovation (new shoots grow from axillary buds outside the leaf sheaths). In the latter case, the result is the ability of the grass to spread horizontally and blanket an entire area.

The vast majority of grasses also exhibit hemicryptophyte growth, which means that their buds are at or near the soil surface. This is one of the key mechanisms that allows grasses to withstand repeated defoliation via grazing or fire, and thus create climax communities that demonstrate an alternative biome state. This trait also means grasses do not necessarily need to maintain above ground structures during periods of extreme stress, such as droughts and cold, and it is the common reason that people assume grasses are so successful.

Bamboo sp (probably Bambusa vulgaris)

5. Transformation of Environments

The ability of members of the Poaceae to significantly transform their environment is perhaps the primary key to their success. By changing their surroundings, grasses create a hostile environment for other plants (including trees and shrubs) that may usurp their dominance, and even relegate them to minor components of the biota.

The way grasses transform the environment is rooted in their makeup. The reproductive fecundity of the grasses allows them to exist in numberless hordes, and their growth forms enable them to blanket entire habitats in contiguous swards, denying food, water and sunlight to competing plants. Their enormous populations, enabled via wind pollination, also allows them to use biotic feedback mechanisms that utilize fire and herbivore grazing to transform closed canopy forests into grasslands, and later maintain this alternative climax state. 

African Tropical Grassland (Savanna), by Gossipguy)

All the factors above combine to give to the Poaceae an invasive and aggressive quality that is perhaps unmatched in the plant kingdom. It allowed the grasses to range far and wide, colonizing all four corners of the world, and transforming vast lands into the wide open spaces that we see today. 

LITERATURE CITED

Beauchamp, Vanessa B.; Koontz, Stephanie M.; Suss, Christine; Hawkins, Chad; Kyde, Kerrie L.; Schnase, John L. (2013). "An introduction to Oplismenus undulatifolius(Ard.) Roem. & Schult. (wavyleaf basketgrass), a recent invader in Mid-Atlantic forest understories". The Journal of the Torrey Botanical Society. 140 (4): 391–413.

Beer, C., Reichstein, M., Tomelleri, E., Ciais, P., Jung, M., Carvalhais, N., Rodenbeck, C., Arain, M. A., Baldocchi, D., Bonan, G. B., Bondeau, A., Cescatti, A., Lasslop, G., Lindroth, A., Lomas, M., Luyssaert, S., Margolis, H., Oleson, K. W., Roupsard, O., Veenendaal, E., Viovy, N., Williams, C., Woodward, F. I. & Papale, D. (2010). Terrestrial gross carbon dioxide uptake: global distribution and covariation with climate. Science 329,
834–838

Bennett TH, Flowers TJ, Bromham L. Repeated evolution of salt-tolerance in grasses. Biol Lett. 2013;9:20130029-20130029

Cope, T., Gray, A. J., Tebbs, M. & Ashton, P. (2009). Grasses of the British Isles. Botanical Society of the British Isles, London.

Estep, M. C., McKain, M. R., Vela Diaz, D., Zhong, J., Hodge, J. G., Hodkinson, T. R., Layton, D. J., Malcomber, S. T., Pasquet, R. & Kellogg, E. A. (2014). Allopolyploidy, diversification, and the Miocene grassland expansion. Proceedings of the National Academy of Sciences of the United States of America 111, 15149–15154.

Gibson, D. J. (2009). Grasses and Grassland Ecology. Oxford University Press, Oxford.

Hibdige, S.G.S., Raimondeau, P., Christin, P.-A. and Dnning, L.T. (2021), Widespread lateral gene transfer among grasses. New Phytol. https://doi.org/10.1111/nph.17328

Holm, LeRoy G.; Plocknett, Donald L.; Pancho, Juan V.; Herberger, James P. 1977. The world's worst weeds: distribution and biology. Honolulu, HI: University Press of Hawaii. 609 p.

Linder, H.P., Lehmann, C.E., Archibald, S., Osborne, C.P., & Richardson, D.M. (2018). Global grass (Poaceae) success underpinned by traits facilitating colonization, persistence and habitat transformation. Biological Reviews, 93.

Magnusson, Borgthor & Magnússon, Sigurður & Ólafsson, Erling & Sigurdsson, Bjarni. (2014). Plant colonization, succession and ecosystem development on Surtsey with reference to neighbouring islands. Biogeosciences. 11. 5521-5537. 10.5194/bg-11-5521-2014. 

Meyer, Susan & Nelson, David & Carlson, Stephanie. (2004). Ecological Genetics of Vernalization Response in Bromus tectorum L. (Poaceae). Annals of botany. 93. 653-63. 10.1093/aob/mch088. 

Moray, C., Hua, X. & Bromham, L. Salt tolerance is evolutionarily labile in a diverse set of angiosperm families. BMC Evol Biol 15, 90 (2015). https://doi.org/10.1186/s12862-015-0379-0

If scientific names became common (the case of Avena in Peru)

Avena fatua spikelets in Ollantaytambo, Peru

I eat a bowl of oatmeal everyday, and during our trip to Peru I tried to keep the same daily routine. Thus, we visited small grocery stores and super mercados in search of this food item, as well as water and various veggies. 

During one such trip I was startled to notice that the oatmeal packages in the store shelves were all labeled "Avena"!

Oatmeal for 1.30 soles!

Avena of course is the genus name of the oats, including the cultivated species Avena sativa. I have been boning up on my Spanish, and it was a small revelation to find out that in that language, oatmeal is known by the genus name of the plant.

Avena fatua in the Moras Salt mines in the Sacred Valley of Peru

This is I think similar in the way Spanish (and several other languages) use modifications of the species name of corn to designate that particular food plant. The binomial is Zea mays, and in Spanish the word for corn is "maiz", just like some other countries call it "maize".

Spikelets in A. fatua, some showing empty glumes

I've found this custom eminently laudable and something that would help (in a very small way) introduce laypeople to scientific nomenclature. Wouldn't it be interesting if rice is called "Oryza", or barley called "Hordeum"?

Maybe even fictional novels and movies could help spread the use of such monikers. I remember Stephen King, in his Dark Tower novels, uses the word "Oriza" to designate various items in the work that are associated with rice. These included a society of women warriors called "Sisters of Oriza", who wielded plate-like throwing weapons called orizas, and whose founder was named Lady Oriza. 

Seeds between dried glumes

Finally, speaking of  "Avena", during the trip one of the most common field grasses was of the genus Avena, likely Avena fatua. I saw this species all over the Sacred Valley area, including at the ruins of Ollantaytambo and Moray, as well as the town of Urubamba and the Moras Salt Mines. Even though this is considered a weedy introduced species, I've found the plant quite attractive, with its many drooping large and awned spikelets.

Just because it's weedy, does not mean it can't be physically attractive!

A Mountain Bamboo in Machu Picchu

Note: Due to the rain at the time, I had to resort to phone pics at times, so I apologize in advance for the quality of those images. 

The rain and drizzle could not fully detract from the beauty of Machu Picchu, but it did hinder my ability to take good photographs. The fact that I was also part of a tour and needed to go as fast as the tour guide also affected any botanizing that I might have wanted to do.

Nevertheless, I did manage to see some interesting specimens in the rush to finish the tour, and among the grasses I found I spotted individuals that looked like bamboo.

Lining the path

Some of the bamboo-like individuals carpeted the side of the paths, while others draped over the passing people as they trudged along beneath. All had delicate and slender leaves, and were somewhat vine-like in their general habit. They were overall one of the best looking of the plants in the park, and quite distinct from the surrounding vegetation.

I decided later that they were of the bamboo genus Chusquea of the grass subfamily Bambusoideae, and after further research perhaps the species Chusquea delicatula. Members of the genus Chusquea are sometimes called the South American mountain bamboos, which I'll admit is a really cool common name.

Chusquea delicatula draped above passersby

C. delicatula itself is an Andean bamboo that has very long and thin culms. It is viney, and the nodes sport side branches that form star-like shapes (see pic below). The images of this species that I found on the web seemed to show a rather more delicate looking bamboo, but perhaps the vagaries of living in the wild instead of luxuriating as a somewhat more pampered ornamental makes a difference. Either way, I am always happy to accept corrections to my identifications. 

Nodes with side branches forming star patterns (red arrows)

Chusquea is the most diverse neotropical bamboo genus, and has the widest latitudinal range of any bamboo genus, occurring from 24 degrees North in Mexico to 47 degrees South in Chile. It also has the largest altitudinal range, and can be found from sea level to over 4000 m. Species in this genus are sometimes dominant parts of montane forests and high altitude grasslands. Machu Pichu at 2400 m is seemingly perfect for C. delicatula, and I saw quite a number of these grasses during my tour of the park.

Chusquea delicatula (?)

Unfortunately, the rain and the somewhat rapid pace of the tour meant that I could not really spend much time observing and photographing the specimens. They are beautiful plants, with their arching habit and dark green slender leaves. I hope that the next time I am in that area, I can hike the Incan Trail to Machu Picchu, and thus have a lot more time to devote to what has become one of my favorite bamboo groups.

Part of a bamboo looms over a group of rain-soaked tourists

The Rock Growers of the Sacred Valley in Peru

Using a wide angle lens to photograph Machu Picchu scene

The Sacred Valley (Valle Sagrado) area in Peru boasts some of the most beautiful landscapes in the world. It is dotted with the ancient ruins of Incan structures, their smooth stone walls fitted seamlessly together. Hidden within their intricate puzzle-like geometries lie secret images of animals, including those that this amazing people held sacred,  such as snakes, condors,  and pumas.

I visited this place last week, including the ruins of the world famous Machu Picchu, as well as the ruins of Pisac, Ollantaytambo, and Saqsaywaman. Remarkably, and especially in the wetter environment of Machu Picchu, the depressions and crevices in the stone walls and boulders held various plants, including some tiny grass species that were wonders to behold.

The genus Ctenium of the subfamily Chloridoideae is one that I have so far seldom encountered in the USA, but I found gorgeous specimens of this grass both in the ruins of Ollantatytambo and in Saqsaywaman.

Ctenium flowerhead in Saqsaywaman

Ctenium inflorescence have a characteristic form, with the spikelets in rows on only one side of the flowerhead. Some flowerheads also twist and curve as they mature, creating attractive botanical structures.

Ctenium growing on mossy soil on rock in Saqsaywaman

In Saqsaywaman, I found a thriving colony of this grass in a single large boulder. The rock had small depressions filled with moss and soil, and in each of these depressions lived one or more individuals, many of whom drooped as they were bursting with bunches of colorful flowerheads.

Ctenium inflorescence in Ollantaytambo

In Machu Picchu, I also found a beautiful tiny species that nestled in the moist crevices of stone walls. I only found these in a localized area in that park, but it was amazing to discover every single one of the individuals as the tour wound its way past that area. The dark green leaves seemed to shyly peek from their rocky cradles, and the spikelets were so tiny (perhaps 1 mm long, not including the long awns) that I had to use full magnification on my macro lens.

Tiny spikelets of unknown sp growing on rock walls in Machu Picchu

The tiny spikelets themselves with their single awns remind me of Muhlenbergia spp. But the overall habit of the plants could not have been more different. Instead of the characteristic thin bladed bunch grass that I have seen as ornamentals and beach residents, these miniscule jewels sported relatively thicker grass blades.

Tiny spikelets of wall growing unknown sp. in Macchu Picchu

The difficulty in taking good photos of the tiny specimens were further exacerbated by on and off rain. It was drizzling occasionally when we were there, and many of the flowerheads of the specimens were decorated in droplets of water. The rain also prevented me from using my camera during parts of the tour. 

Tiny grass sp growing out of crevice in moist rock wall in Machu Picchu

As mentioned in previous posts, the members of the Poaceae are relatively scarce as true epiphytes, probably due to the prevalence of wind pollination in the family. But given even small portions of soil, moss, or other available substrate, it seems that grasses are also fully capable of exploiting these niche habitats.

Using a wide angle lens to view of the ruins of Ollantytambo

Accidental Epiphytic Beauty

Cenchrus setaceus

In December 2020, I discovered a grass that was perched between two large branches of a tree.

This made me start thinking about why the Poaceae, even though it's the 4th or 5th most speciose plant family, did not really have real epiphytic species. I discussed this mystery in that old post, and came to the conclusion that it probably has to do with the fact that grasses are creatures of the light and wind. True epiphytes are pretty much all animal pollinated, and tend to occur in forested areas.

But "accidental" grass epiphytes do occur, and I came upon an instance of this again when strolling around a neighborhood and canvassing the many ornamental grasses that graced its grounds.

Cenchrus setaceus inflorescence (white stigma and yellow anthers)

Varieties of Cenchrus setaceus (subfamily Panicoideae) were in evidence everywhere. They have beautiful cylindrical flowerheads that are tinged with purple, and I was gazing at a group of the ornamental C4 grasses when I was astonished to find that two of the specimens were literally growing from the trunk of nearby palm trees! Not only that, but both had flowerheads rising from their tops, a testament to the tenacity of the individuals.

Flowering accidental epiphyte (red arrow points to base of grass)

I examined one of them (see image below), and found that the shoots of the grass emerged from what I think are balls of moss that had adhered to the trunk. The moss piece felt hard to the touch and crumbled slightly when I handled it. So it is possible that seeds from this species had landed on the moss, and had been able to grow to maturity in such an unusual location.

Rooted in moss (Cenchrus setaceus)

Although Florida is considered a humid area, it does have a dry season when rain does not occur for many days or even weeks on end. But the air must retain enough moisture that allows not only mosses to survive on the exposed palm trees, but other more complex plants as well, such as the ferns and Tillandsia "air plants" that decorate many of the tree limbs here. In addition, this is a suburban community, and I have a feeling the various underground sprinklers that dot the landscape contribute some water as well. Finally, this species has been known to become invasive, and thus might possess some rugged attributes that belie its graceful appearance and allow it to colonize inhospitable locations.

But whatever the reason for their growth and survival, the two C. setaceus specimens certainly prove that the Poaceae might not have many true epiphytes, but it's not because of lack of trying.  

Mutual Assured Destruction: Revisiting an unlikely occupation

Flowering inflorescence of Imperata cylindrica, with orange anthers and purple stigmas

About a year ago, I wrote about how an invasive grass (Imperata cylindrica) started taking over an island in the parking lot of a building complex.

March 2022

A month or so after I posted that, the owner of the lot acted and when I next saw the lot in May, the entire island had been stripped of its vegetation and probably drenched in herbicides. They had pulled the trigger and given up on being able to selectively weed out the invasive, assuring the destruction of both the invasive grass and all the ornamental plants around it. Even so, I still saw a few blades of cogon grass poking out of the scene of destruction.

May 2022

I visited the area again last week, and the island was still bare, with even the two trees seemingly dead. The owners must have been repeatedly treating it in order to prevent any new regrowth of I. cylindrica. This repeated treatment and monitoring for a minimum of 2 years is a common practice when treating I. cylindrica infections, in order to ensure total eradication.

March 2023

I decided to revisit this old haunt because I had encountered another cluster of I. cylindrica that was weirdly similar to the situation in that parking island last year. In this new case, the invasive grass had grown on the mulched beds of two sidewalk Palm trees, and covered almost 20 m² at the bases of the trees. 

I. cylindrica cluster around the bases of sidewalk Palm trees

I had spotted it even from a distance because some of the ramets in the cluster were flowering, even though they had been cut close to the ground. When I came near I noticed that the white flowerheads were covered in orange anthers and purple stigmas.

I'm very surprised the cluster had avoided being eliminated by the groundskeepers in the neighborhood, who are usually quite liberal with the use of herbicides to keep most of the area weed free. Perhaps the presence of the palm trees, which are also monocots and thus susceptible to the same types of chemicals as grasses, had so far dissuaded them from acting.

I'm also slightly surprised that the thick mulch (tree bark) around the tree bases have had very little effect in preventing the spread of the invasive. The tenacity of this species can be admirable, even as the authorities curse its weedy nature, and I'll be sure to revisit the cluster occasionally when I can to see how it fares.

A nearby field of flowering I. cylindrica

Poaceae on the App: Grass Pro SA

Summary: It's a fantastic mobile app that went far beyond my expectations, and would be a great help for anyone who wants to learn about grasses in the southern part of Africa.

My first experience with a mobile app for grasses was for the grasses of Montana, and I found it useful and quite portable, since I brought my phone everywhere.

So when I heard about a new app called Grass Pro SA that focused on South African grasses, I immediately downloaded it from the Google PlayStore for my Samsung Android smartphone, and was immediately appreciative of its quality.

The home screen has a rotating background of very nice images of various grass inflorescence, and displays all the main sections of the app.

The Grass List is simply a long list of all the species in the app (there were 324 species when I tested it, but I assume they add to it over time), with the capability to search for specific species by name. The subsections within it contain more detailed info on each species, including nice images, the distribution, and personal sightings. More about this features later below.

Grass List

The Sightings section allows the user to submit and sync sightings of species that they find to the common database. This is a great feature that is not in the more basic Montana app, and allows users to participate actively in the building of the database.

Help and About gives very detailed information about using the app, as well as credits to those people responsible for its creation.

The Settings section is interesting, because it allows you set the language options for the species and common names. It was cool to be able to see what the common name of Imperata cylindrica is in Afrikaans for example (Donsgras), although most of the African common names seem to be missing (I tried Zulu and Xhosa).

Settings Section

The Location Section is one of the best features of the app, and it is not available in the free evaluation version. In the main page you can select whether you want to see grasses in your current location (I assume the app uses the phone GPS), from a selected area in a map, or whether you want to see all grasses in South Africa.

Location Main Page

I decided to try out the Select from map subsection. As you can see from the image below I selected an area in the southwest corner of Namibia (by just tapping at it), and the app immediately noted that it has records of 20 grass species in that area.

Finding species in a specific map location

I then tapped the search icon next to the label "20 grasses", and it brought me to a page where I was able to filter the results by specifying particular traits (see image below). The app allowed filtering using 8 different methods, and this was something that was really amazing to me. 

Ability to filter results via 8 methods

Not only can you filter via the usual structural traits, but you can also filter using such unusual ways as ecological information (grazing value, plant succession stage. ecological grazing status, weeds), and even via common uses! (see image below).

Filtering via common uses

Just to show how the process works, I went the route of using the major physical attributes to identity a specimen.

In this case, I got the option of filtering the 20 species using such features as plant height, inflorescence, spikelet, and leaf blade width (see image below).

Filtering using major or main plant features

I decided to go with inflorescence, and tapping it took me to another subpage, where I was able to select from various types, such as unbranched, panicle, and digitate flower spikes (see image below).

Selecting type of inflorescence

A small icon ("i") next to each image allowed me to go to a help and information page that went into detail about the inflorescence types, which was really helpful.

Info page about inflorescence types

After selecting unbranched, rounded inflorescence, I was taken to a list of 3 grasses that met my criteria.

Since I knew the species Cenchrus ciliaris, I picked that, and I was taken to a species profile page (see image below). This page not only contained full descriptions of C.ciliaris, but it also had several nice photographs showing the habit and fine detail of the species. In addition, it also displayed the full distribution of the species in southern Africa.

I cannot emphasize enough how cool this little mobile app was. It went far beyond my expectations, and a lot of work and effort must have gone into creating it. I highly recommend it for anyone who would like to identify and learn about the Poaceae in the southern part of Africa, and I hope similar apps are created for other regions of the world. 

I think my only minor gripe is that a lot of the African languages did not seem to have common names for the species, but both Afrikaans and English common names were included. The app was also a bit confusing when I used Current Location to try to see species near me. Since I am located in the USA, I thought that it would note down zero grass species nearby, but it seemed to indicate the presence of all 324 species. 

The evaluation version is free, but to see all the species in the database (324 species when I tested it), and be able to use the Location feature, the cost is an annual subscription of around US $10 (including tax).