Dinosaur fodder

The common horse-tail, Equisetum arvense, is an ancient species of plant whose ancestors were browed by dinosaurs. Modern horsetails are only a few centimetres high but their ancestors included tree-like species up to 200 feet in height living in the Carboniferous forests. They all evolved long before the flowering plants came along and they produce  spores rather than  seeds. 
Horse-tails grow in moist, rich soils in all parts of the world except Australasia. Some, including ours, produce two kinds of shoots. The first shoots to emerge in the spring are the reproductive squad and are topped with cone-like clusters of spore capsules. These are the ones in the photograph. In a couple of weeks time they will be replaced with green shoots whose role in life will be photosynthesis, growth and replenishing the energy stores.