Everyone who has grown a lawn knows how the grass keeps growing after it has been mowed. Few gardeners notice that the pointed tip of each blade, once lost, is not regenerated. Instead, the blades continue growth from near their bases, from what are known as intercalary meristems, areas of cell division inserted between the blade and the stem. The evolution of intercalary meristems enabled various types of grasses to survive in prairie habitats in association with herds of grazing animals, such as deer, antelope, bison and, later, domesticated cows. As long as the animal’s teeth simply snip
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