Erigeron divergens (spreading fleabane) Arches National Park

Description:

Summary[edit] Description: Erigeron divergens Torrey & Gray, 1841 - spreading fleabane in Utah, USA. Plants are multicellular, photosynthesizing eucaryotes. Most species occupy terrestrial environments, but they also occur in freshwater and saltwater aquatic environments. The oldest known land plants in the fossil record are Ordovician to Silurian. Land plant body fossils are known in Silurian sedimentary rocks - they are small and simple plants (e.g., Cooksonia). Fossil root traces in paleosol horizons are known in the Ordovician. During the Devonian, the first trees and forests appeared. Earth's initial forestation event occurred during the Middle to Late Paleozoic. Earth's continents have been partly to mostly covered with forests ever since the Late Devonian. Occasional mass extinction events temporarily removed much of Earth's plant ecosystems - this occurred at the Permian-Triassic boundary (251 million years ago) and the Cretaceous-Tertiary boundary (65 million years ago). The most conspicuous group of living plants is the angiosperms, the flowering plants. They first unambiguously appeared in the fossil record during the Cretaceous. They quickly dominated Earth's terrestrial ecosystems, and have dominated ever since. This domination was due to the evolutionary success of flowers, which are structures that greatly aid angiosperm reproduction. The plant shown above is a member of the daisy/sunflower family (Asteraceae), the second-largest group of angiosperms in the world, with >23,000 described species. The spreading fleabane has many dull green-colored stems with small, narrow to moderately narrow, elongated leaves. The flower consists of a small, yellowish, central disk surrounded by narrow, elongated, whitish petals. Erigeron divergens occurs in a variety of open habitats in Mexico, western America, and southwestern Canada. Classification: Plantae, Angiospermophyta, Asterales, Asteraceae/Compositae. Date: 17 June 2009, 15:16. Source: Erigeron divergens (spreading fleabane) (Arches National Park, Utah, USA) 3. Author: James St. John.