April 2024

12 Buckden Roundabout April 2024 Grasses Grasses Grasses are probably one of the most important but under - considered group of plants on our world. Found in all terrestri- al habitats they dominate around 40% of the land surface of the planet. Poaceae or Gramineae, as the family is known, has some 12,000 naturally occurring species worldwide with around 160 species in the UK. This does not include the Sedges or the Rushes which, despite some species having grass in their name, are not of the same family. Diversity is one of the keys to the family ’ s success. Consider the variation between Early Sand Grass, considered one of the smallest species, approx. 50mm tall with a stem diameter of less than 1mm compared to the Giant Bamboo reaching 46m high with a stem diameter of 36cm and with each stalk weighing close to ½ a tonne. They are so adaptable that a grass species is one of the few plants native to Antarctica. Initially thought to have evolved around 55 million years ago, recent improvements in fossil analysis have found residue on dinosaur teeth suggesting grasses were in existence up to 110 million years before the present. They have evolved to grow from the stem base rather than from the stem or leaf tip. This allows regeneration to easily take place if the upper part of the plant is removed. Hence, they can stand regular cutting or grazing and regenerate rapidly from fire and other natural dis- asters. Because of the way they grow, grasses form the main diet of a huge number of wild species. On the African savannah Zebra and many Antelope species graze whilst an English meadow grassland provides food and shelter to many small mammals like the Harvest Mouse and Field Vole. Even carnivores will eat grass, Brown Bears are known to graze extensively when other food sources run short and one species of bear lives on nothing else, the Giant Panda. These are just the species that you no- tice, many thousands of invertebrate species, from Grasshop- pers and Crickets to Leafhoppers and Aphids and many differ- ent larvae and caterpillars all rely on grasses as a food source. To combat this some species have evolved a mechanism that deposits silicates in their leaves leaving a sharp edge. Mostly found in tropical species these can be capable of cutting through cloth and even some UK species are capable of draw- ing blood from an unwary finger. But it ’ s not just wildlife that is sustained by grasses. Of all crops grown by man about 70% are grasses. Through direct consumption, mainly of their seeds, grasses provide just over half of man ’ s dietary energy. This does not include the growing of grass to feed grazing animals destined for the human food chain. Further products originating from grass include beer and spirits through the processing of wheat and barley and half the world ’ s sugar is derived from sugarcane, another grass spe- cies. Add to this its use in construction, Bamboo makes excel- lent scaffolding, its value as an amenity, where would outdoor sports be without grass pitches, and its aesthetic use in many gardens it can be seen just how useful this plant family is. - Gregory Belcher (Snr Reserves officer, Grafham Water) Bamboo forest, South Korea, photo by Lance Vanlewen African savannah grasses, photo by Christopher T Cooper Wheat—a species of grass