Guinea Grass and the Licorice Jellybean

BY DR. MEGAN CLAYTON AND DR. BARRON RECTOR, Extension Range Specialists, Texas A&M AgriLife Extension Service

As we find ourselves in the Easter season, my mind often goes to one of my favorite kind of forages, jellybeans! These colorful small beans look great in a candy jar and offer many fun flavors that may even take you back to a certain place or family gathering. I enjoy all but one – the licorice jellybean. It’s hard for me to see why someone would prefer licorice to all the other fruity flavors, although we all know a small handful of people who claim to love licorice or have learned to tolerate it in the jellybean mix.

I liken Guinea grass (Megathyrsus maxima) to licorice jellybeans. Although there are a handful of people who may wish for more Guinea grass or consider it to be one of their premier livestock forages because it works well for their operation, many people would either like to eliminate it from the “jellybean” mix or have learned to live with it.

Far from its homeland of Africa, this tall, awkward grass with straight stems adorned all the way up with weeping leaves thrives in our drought-prone lands of South Texas. Experimental plantings of the grass have been documented in Kingsville during the mid-70’s, although its presence was noted in Hitchcock’s Manual of the Grasses of the United States in 1935. Could this silent creeper be the cattle forage or hay producer that keeps our livestock operations profitable, as much of tropical America has discovered? Alternatively, will this grass eventually spread throughout native rangelands, decreasing plant diversity necessary for wildlife species to thrive?

There is a good chance you have run into the subject of this story, whether in an open field or underneath a shade tree of a service station. Guinea grass has adapted to many different environments, especially southern Texas. In Shaw’s Guide to Texas Grasses, he documents Guinea grass occurrence in 23 counties, Dallas being the furthest north, although its cold tolerance is not completely understood. Not only can the grass grow up to 8 feet tall, but it also uses rhizomes, or underground stems, to create new plants and quickly dominate an area. A leafy, highly competitive grass could easily be viewed as a hero, especially to those ranchers who face many challenges when trying to produce forage for livestock in dry regions. Like many grasses, livestock prefer Guinea grass when it is regularly grazed to maintain high digestibility. Some ranchers hay it, creating a lasting resource for their cattle when the rain stops or when other grasses in South Texas lose their nutritional value. Other ranchers have noted Guinea grass to encroach on areas previously established with buffelgrass (Cenchrus ciliaris), another introduced South Texas forage grass for cattle native to India and Africa.

As is the case with many introduced grasses, Guinea grass aggressively outcompetes other native vegetation leaving less plant diversity in the area. Wildlife managers in the sand plains of South Texas have indicated a harsh reduction of valuable forbs for quail, such as cowpen daisy, woolly croton, and annual sunflowers, in areas where Guinea grass has invaded. How much can be tolerated before land becomes essentially useless for many wildlife species?

Unlike the characteristically black licorice jellybean that is easy to recognize in a mix, Guinea grass can be very difficult to tell apart from other grass species, especially Kleingrass (Panicum coloratum; introduced from Africa) and Switchgrass (Panicum virgatum; native to Texas). Switchgrass can grow as tall as Guinea grass, if not taller, although you will rarely see Kleingrass over six feet. Guinea grass stems are very thin like Kleingrass, but they grow straight up and do not fall down right away. Switchgrass has very stout, hollow stems that grow straight up. Guinea grass usually has the shortest leaf that “weep” over towards the ground with many short hairs on the sheath collar, the area where the leaf attaches to the stem. Kleingrass has a white midvein on the lower part of the leaf and small glands or pimples on the side of the leaf and are sharply pointed. Switchgrass leaves are often a yellow-green color and taper at the ends. Guinea grass has seeds that are bigger than Kleingrass, but equal to or bigger than switchgrass seeds.

Table summarizing differences between Guinea grass and lookalikes, Kleingrass and Switchgrass.

Guinea Grass Up to 8’ Thin, grow straight up

Shortest, weep over, hairs on sheath collar

White midvein on lower part of leaf, small glands on side, sharply pointed

Yellowgreen, taper at ends Large seed

Kleingrass Up to 4.5-6’ Thin, tend to fall over Large seed

Switchgrass

3-8, can be over 10’ Stout, grow straight up, hollow

Large, comparable to Guinea grass

Traditional management with prescribed fire may alter the plant community as Guinea grass increases the natural fuel load, creating a hotter fire and one that may more readily burn up into the brush canopy. Winter burns are typically found to favor Guinea grass, with the plants potentially reaching 7 feet tall within a few months of the burn. Research has shown that summer prescribed fire can reduce the presence of Guinea grass and increase the diversity of native plants in the shortterm, especially when combined with patch grazing by cattle. spraying with glyphosate, a broad-spectrum herbicide, to control small colonies or heavily grazing the grass if that is practical without overgrazing other beneficial forages.

So, what is Guinea grass’s weakness? Reports indicate that the grass does not like to be waterlogged. Unfortunately, South Texas is not often under standing water and even then, we would have to balance the desire to control the grass with the impacts on other plant species and the flush of mosquitos this would no doubt bring! Our week of abnormally low temperatures in late February may have killed the tops of these grasses, but they can be expected to recover with the onset of warming spring temperatures or be reborn from seeds in the soil from past year’s flowering and seed-set.

Although there are differing opinions on Guinea grass and licorice jellybeans, we can likely all agree that this spring season offers us a time of renewal in many forms. It is a great time to rethink land management practices to move us towards our land goals and be better stewards for the long-term health of rangelands.

1650 – Guinea grass regrowth after mowing on the side of Highway 281 in Hidalgo County. Photo credit: Barron Rector

Guinea grass after fire – Guinea grass seedlings (left) and resprouts (right) less than three months after a February wildfire in the sand plains of South Texas. Photo credit: Barron Rector