Vallisneria americana, aka "tapegrass," aka "water celery," aka "Val" is a lovely vascular plant that lives its entire life beneath the water's surface in lakes, rivers, and slightly brackish estuaries.
In Florida, Val is threatened by declining water quality and (in estuaries) by fluctuating salinity levels. It can tolerate up to about 1/3 the salinity of seawater, but it dies if it gets saltier than that. Another threat to Florida Val is grazing by the huge, non-native, aquatic snail Pomacea insularum, aka the Island Apple Snail.
This year at Florida Gulf Coast University I have my first graduate student, Shannan. She's going to do a project looking at the interactions between salinity, snails, and Val. It's going to be awesome. Today we scored big when my colleague David Ceilley offered to share with us his personal stash of Val, which was growing in a cattle tank behind one of our academic buildings.