<P> 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 . 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 CO and warm , dry conditions of the tropics over the last 10 million years . </P>
<P> 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 . 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 CO and warm , dry conditions of the tropics over the last 10 million years . </P>
when did the first grass appear on earth
when did the first grass appear on earth
around 40 million years ago
around 40 million years ago