For many years the HBS has presented talks for our members and friends on the third Friday of every month in the Fernkloof Hall. As a botanical society we like to take these opportunities to persuade people that “Plants matter”. Jim Sweet, our speaker on Friday 16th March, could not have addressed a topic closer to our core belief. “Grasses: where would we be without them”.
Listening to Jim, we realised to what an extent the whole human race is underpinned by grasses in the form of cereals for our staple foods, and other grasses for a host of uses including construction (bamboo), thatching (Hyparrhenia), biofuel (sugar cane) medicinal (common couch grass), essential oils (lemon grass) and erosion control (vetiver grass). More obviously, grass supports a huge biomass and diversity of domestic stock and wildlife through natural grazing in the prairies, pampas, steppes and savannas of the world.
Grasses may be annuals, which complete their life cycle in a single season, or perennials which can last indefinitely. The former need to be prolific seeders but require only a shallow root system. The latter also produce seed but rely mainly on regrowth and a well developed root system. Some perennial grasses spread by runners which can be above ground (stolons) or below ground (rhizomes). Kikuyu grass has both, making it a successful turf and grazing grass but difficult to eradicate!
One reason why grasses are so successful is that they are difficult to digest hence, to access this food source, herbivores have specialised digestive systems. Scientists have recently identified the gene responsible for cell stiffness and have shown that grass can grow quite well without it. Jim concluded by suggesting that it might not be long before we too are eating grass!
Article by Deirdre Richards