Grasses

    The various structures provide the features used in identification of grasses. The flower, called the inflorescence, is the easy place to start. However, some species are so similar that you may need to look more closely at other parts of the plant. The diagram below illustrates the basics.

    The stem of a grass is seldom branched. It is mostly hollow and straight, interrupted at intervals by swollen joints called NODES. The stems are called CULMS.

    Some grasses have stems which grow along the surface of the ground, and result in new shoots. These horizontal stems are called STOLONS. If the horizontal stems are below the ground, they are called RHIZOMES.

    Leaves start at NODES. The part of the leaf closest to the node encloses and protects the shoot in a LEAF SHEATH. The further portion of the leaf opens out and is the LEAF BLADE. The LEAF BLADE is usually long and narrow, and tapers to a point.

    Where the SHEATH and the BLADE meet, there is a small tissue flap called the LIGULE. This flap is sometimes nothing more than a fringe of hairs. It may also happen that the LIGULE has little projections on either side called AURICLES.

    The flower head of grass is called INFLORESCENCE. There are no petals, and the flower is protected by scales called a FLORET.

    All the florets are protected by a second set of scales called GLUMES. GLUMES may have bristle-like extensions called AWNS.

    The entire structure – Florets, glumes, and awns – is called a SPIKELET.

    The arrangement of the SPIKELETS into the INFLORESCENCE is often the first key in grass identification.

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    This grassland species is regarded as the most valuable grass in sourveld. Themeda triandra grows abundantly when the veld is in good condition.

    The grass is green to blue-green, tufted, and is often flushed with pink. As it ages, the colour deepens to red. The spikelets (grass flowers) form wedge-shaped clusters, sometimes hairy, which tend to hang down.

    The species name tri (three) and andr (man) is Greek, referring to the three male spikelets surrounding the bisexual spikelet in each cluster.

    Themeda is fire resistant, increasing with frequent burning provided it is not overgrazed. The grass is palatable, and an important and well-known grazing grass.

    The grass grows in regions with average to high rainfall, and is common in altitudes between 1300 and 3000 meters above sea level.

    Themeda triandra occurs only in southern Africa, though it is one of 18 Themeda species occurring across the world.

    Interesting fact: The long awns (long bristle-like projections) of the spikelet twirl when wet, and drive the seed into the ground.

    Flowers: between October and July.

    Height: between 300mm and 1500 mm

    Uses: grazing; indicator of good veld conditions

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