Equisetum

The plant you see in the photo, Equisetum or "horsetail" is an aggressive weed with a very interesting history (taken from wikipedia):

Equisetum is a "living fossil" as it is the only living genus of the entire class Equisetopsida, which for over one hundred million years was much more diverse and dominated the understory of late Paleozoic forests. Some Equisetopsida were large trees reaching to 30 meters tall.[3] The genus Calamites of the family Calamitaceae, for example, is abundant in coal deposits from the Carboniferous period.

These are babies (at most 12 inches tall) compared to what they were like back in its heyday. I always did think they looked a bit prehistoric... They just started to grow and they end up developing a top that looks like a brush used to clean out bottles or other round objects.

Hope you all have a wonderful weekend!