Bidens sp. - beggar's ticks in Virginia, USA. (October 2016)

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.

Beggar's ticks are a member of the daisy/sunflower family. Their fruit are a type of "burr" that readily sticks to the fur of animals or the clothing of people. A cluster of radiating burrs occurs at the tips of branches. Individual burrs are easily detached when disturbed. The distal ends are trifid and barbed (click on the above photo to zoom in and see the small barbs).

I probably had about a thousand of these on my pants, shirt, shoelaces, and hat after visiting this site.

Classification: Plantae, Angiospermophyta, Asterales, Asteraceae

Locality: Grassy Branch Outcrop - base of roadcut on the northern side of Rt. 603, just downstream from the Big Laurel Creek-Grassy Branch confluence, west of the town of Troutdale & east of the town of Konnarock, southern Smyth County, southwestern Virginia, USA

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