The species has a cunning ability to plant itself, using seeds that comprise short, hard, needle-sharp spikes, easily able to pierce clothing and skin. Stabbing pains accompany movement and skin irritation soon follows. Trying to pull them out by their thin, wiry, brown, 7cm-long tails doesn't work. The tails detach, but barbs keep the short, spiky seed heads firmly embedded. The only solution is to sit and patiently extract the seeds, working them through the clothing or body hairs to free the barbs.

Animals, however, can't separate the seed from its hairy shaft. Some time and distance after attaching itself to a passing creature, the seed will work loose and fall to the ground. Here moisture from overnight dew or rain causes the curled shaft hairs to stiffen and straighten. This unwinding drills the seed into the ground, the barb keeping it in place while it germinates. Most good safari guides will demonstrate this clever drilling action by holding the seed between the thumb and forefinger and licking the shaft, which immediately causes it to unwind.

Spear grass grows in tufts up to 75cm high. When mature, the long brown tails often become entangled in the wind. The grass itself is palatable, easily digested and fairly nutritious. Many animals, particularly mountain zebra, roan and sable antelope and waterbuck, enjoy it. However, when imbedded, seed heads can cause serious damage to an animal's skin, surrounding flesh and coat.

Sheep farmers commonly detest spear grass for the dreadful mess it can make of wool. It's not surprising, therefore, that Zulu warriors described it as inzala, a name the Boers translated literally as assegaigras (an assegai is a Zulu spear).