Coontail 

Ceratophyllum demersum

Also known as: hornwort.

Also known as: hornwort.

Coontail is a submersed aquatic plant and can be easily identified by the "raccoon tail" cluster of leaves at the end of the main stalk. It has slender stems and leather-like leaves. Coontail is called hornwort when it is sold for aquarium decorations. It then spreads into ponds after aquariums are dumped into water bodies.