when did the first grass appear on earth
Evolutionary history of plants By the middle of the Devonian, many of the features recognised in plants today were present, including roots and leaves. Late Devonian free-sporing plants such as Archaeopteris had secondary vascular tissue that produced wood and had formed forests of tall trees. Also by late Devonian, Elkinsia, an early seed fern, had evolved seeds.[9] Evolutionary innovation continued into the Carboniferous and is still ongoing today. Most plant groups were relatively unscathed by the Permo-Triassic extinction event, although the structures of communities changed. This may have set the scene for the appearance of the flowering plants in the Triassic (~200 million years ago), and their later diversification in the Cretaceous and Paleogene. The latest major group of plants to evolve were the grasses, which became important in the mid-Paleogene, from around 40 million years ago. The grasses, as well as many other groups, evolved new mechanisms of metabolism to survive the low CO2 and warm, dry conditions of the tropics over the last 10 million years.