Equisetum hyemale aka Scouring Rush or Horsetail
These living fossils have been around for the past 300 million years, a part of the Carboniferous or Coal Age, and are the last living example of “Sphenophytes” (plants having straight stems, with branches and leaves arranged in regular whorls). “Scouring Rush” gets its name from times past when it was used for scrubbing pans and polishing all sorts of objects, because its ribbed and furrowed stem cells have a high percentage of silica and feel abrasive to the touch. The Equisetum species are in the family, Equisetaceae, which is in the plant division, Pteridophyta. This means that Equisetum species are closely related to ferns, and their reproductive spores are dispersed by the winds. The popular and widely used name “Horsetail” comes from the Latin words equus (horse) and seta (bristle), from the peculiar bristly appearance of the jointed stems of the plants.
The plant bears no leaves, and looks almost like a pot of green bamboo stakes that florists use to support unusually tall plants. The stems are jointed and they come apart at each joint - usually with a loud popping sound. Where the tips (strobilis) are missing, the stems end in a circular depression with brown edges. It is not uncommon to see straw-brown dead tips on top of a healthy green stem. This is probably a safety valve for drought conditions. When water is more plentiful, the plant usually sends out shoots from the top edge of the remaining stem. These little spikes adhere to the stem as though they were welded there. The hyemale species has an insatiable desire to keep its roots very wet. It cannot be over-watered, and is happy to sit in large puddles - in fact, it thrives profusely in watery conditions. Its close relative Equisetum arvense has very little thirst, and can grow and thrive on dry, hard-packed soils.
Thanks Sadhya [photoblog.com] for the help on the ID


but i thinks it's great avatar's tail