How to identify the different types of grasses in African savannahs
BY: Tasneem Johnson-Dollie
To the untrained eye, the African savannah may seem like a monotonous terrain. But, by learning how to identify the different types of grasses, you’ll see just how diverse this landscape really is.
Grasses are the most abundant group of greenery on Earth. And, they’re found in locations across the world: from the dry, desert landscapes of Africa, to the icy cold outdoors of Antarctica.
So, if you were to ask anyone around the world about grasses, it’s highly likely that they’d know what you’re talking about. They’d probably even be able to give you a decent general description of what grasses are.
But how do you go about telling one prickly specimen from a different type of grass?
Let’s start by taking a closer look at some answers to the question, “What is grass?”
What is grass?
Grasses are the spindly plants found growing along sidewalks, or out in wild spaces – like South Africa’s grasslands.
They come in a range of colours and textures. From the stiff, durable, deep-green blades of buffalo grass, to the lanky wisps of gold-and-brown thatching grasses that shudder with every puff of passing air.
All the world’s grasses belong to the plant family Poaceae, and each of these plants is made up of five different parts:
- flowers – the parts responsible for producing seeds
- blade – the leaf of the plant
- culm – the plant stem
- roots – the part of the plant below the ground
- rhizome – a modified part of the stem that grows underground and can put out new roots and stems
- stolon – an adapted part of the stem that can produce new plants.
These plant parts aren’t unique to grasses. But, identifying each different type of grass in the wild starts with being able to spot these features on a spindle of growth poking out among other African savannah plants.
To sharpen your grass-spotting skills, start off by looking at pictures of different types of grasses online or in textbooks. This way, you can get to know more about these plants before stepping out into the savannah.
Compare simple diagrams, then challenge yourself by identifying each part of the plant in up-close pictures of different types of grasses.
And, once you’ve found your grass-examining groove, you can set out and try your hand at identifying the more than 70 different grass types found in South African grasslands.
Further reading: All about the different types of grasses of Southern Africa
Here’s a closer look at how to identify them out in the wild.
How to identify the different types of grasses in African savannahs
On a Bushwise Field Guide’s online or on-site Field Guides Association of Southern Africa (FGASA) Field Guiding course, you’ll learn about the finer details of grass identification once you’re clued up on the basics.
This means that you won’t need to carry around pictures of all the different types of grasses found in the savannah. You’ll be able to identify them by paying attention to some tell-tale features instead.
For instance, because different grass types grow under different conditions and in different ways, it’s easier to tell some of them apart.
One example is when you compare stinking grass with red oat grass. Stinking grass grows in squat, shrub-like tufts and prefers to shoot up out of dense clay soils. But, red oat grass can grow as tall as 1,5 metres and pop out of almost any type of soil. See the difference?
Stinking grass also gives off an unpleasant smell when crushed and isn’t edible. In comparison, red oat grass is one of the most important edible grasses in the African savannah. It’s eaten by wildlife like birds and zebras, and grazing cattle like sheep and cows.
Another eye-catching feature that can help you tell the different types of grasses apart is their inflorescences (or flowering parts). An inflorescence is made up of bunches of flowers called spikelets. And, these spikelets come in three different formations:
- spikes – spikelets attached to the main stem of the plant
- racemes – spikelets found at the end of short stalks attached to the culm
- panicles – spikelets attached to branches that are attached to the culm.
How the appearance of African savannah plants changes from season to season
Compared to the global average of 786 millimetres of rainfall per year, South Africa’s 460 millimetres of annual rainfall makes the country a generally dry region.
But, from one season to another there are significant changes in rainfall that affect the growth of all savannah plants, including the different types of grasses.
The Limpopo province is home to some of the widest stretches of South African grasslands and this region receives most of its rainfall in the warmer months (between October and April).
During this time, you’re much more likely to see different types of grasses at their best: standing tall and shimmering in the sun-soaked savannah.
But, in the colder months, grasses aren’t blessed with as many showers. In some areas, frost may settle in as night-time temperatures drop below zero degrees celsius. This is when you’ll see much less of these leggy savannah plants around, and you’ll have to make do with watching the sunset across sandier scenery.
Added to the dryness of the terrain is the large amount of annual sunshine in Limpopo. With that in mind, you may be wondering, “How do grasses withstand the year-round heat?”
Well, it’s true that atmospheric temperatures can be sweltering at any time of the year: maximum temperatures average at around 22 degrees celsius in winter and up to 40 degrees celsius in summer. But the different types of grasses are adapted to deal with this African savannah climate.
One trick they have up their “sheathes” is their ability to channel water to their most important parts and away from most of their outer layers. This reduces the amount of water that’s lost to evaporation as the warm atmospheric air rubs up against the outer sheaths of these savannah plants.
Eventually, the outer layers of the plant dry out and die, leading to the tawny shade of many different types of grasses.
Under certain conditions – like very cold weather or when water is scarce – grasses go dormant and not much of the plant can be seen above ground at all. This means that some of these savannah plant’s most defining features won’t be on display.
So, you’ll need to find other ways of identifying each different type of grass from one season to the next.
What are other ways of identifying different types of grasses?
If you end up looking at two very similar grass stems, or if you’re trying to compare the tendrils of grasses that could be twins, you’ll need to get out your magnifying glass to be sure.
By zooming in on the collar of these African savannah plants, you’ll be able to tell with more certainty if you’re looking at samples that are the same, or different.
The collar is the area where the leaf blade joins the culm on all the different types of grasses. This landmark is where you’ll find the auricle – a set of sickle-shaped protrusions that wrap around the stem – and the ligule, which is a paper-like scale found inside the leaf blade.
Each of the different grass types has a distinct set of auricle and ligule that sets them apart from every other type of grass.
And, even when you’re out in the African grasslands during a time when grasses are dormant, you may still be able to identify different grass types using these characteristics.
South African grasslands make up almost one-third of the country’s land surface area. So, knowing the African savannah plants that make up the grassland biome can add to your knowledge on the country’s ecosystems in a big way.