This pink color on the Scudder Pond is caused by a native species of aquatic fern called Azolla microphylla (synonymous with Azolla mexicana). Although it looks a lot like Lemna (duck weed) at first glance, this is actually a tiny pteridophyte (fern). One common name for this plant is mosquito fern because it suppresses mosquito breeding. It is also an excellent water quality filter.