Fall 2011 - L-R from top: Astilbe - the corner's not weeds, don't pull; bottom - Japanese Painted Fern; middle - small Water Lil

Fall 2011 - L-R from top: Astilbe - the corner's not weeds, don't pull; bottom - Japanese Painted Fern; middle - small Water Lily supposedly hardy. Also Waterweed (Elodea) (see description) Don't know how deep pond is, so don't know if they lifted the Water Lily for the Winter or not. perennials except for maybe the lily

The other plant blooming (10/1/11) is most likely Waterweed (Elodea). The plant stays submerged and only the flower floats at the top. Wikipedia says "In the fall, leafy stalks will detach from the parent plant, float away, root, and start new plants. This is the American water weed's most important method of spreading". (When it grows in waterways it can sometimes spread to the point of being considered invasive.)

From what I can find Elodea is a good plant for ponds because it's a great oxygenator for the water. It also prevents algae from forming on the pond so no algae preventative has to be added to the pond weekly. Another benefit is that it offers a place for baby fish to hide. :o)