Unlike marine algae, freshwater algae is usually little more than green slime. Much of it is actually microscopic single-celled organisms that form the base of the food chain. That is why the water is green ( when it is green. ) *
Fanwort is a fully aquatic true plant. It grows steadily through the warm months, and can choke-out large areas, then dies back in the winter. Fanwort produces tiny flowers above the surface.
Sedges and Reeds are superficially similar, but actually quite different. But unless you are a biologist - who cares? ( Reeds are grasses, sedges are sedges. )
Sedges
Sedges tolerate a wide range of salinity, from freshwater to seawater, although they seem to grow best in brackish water. So, like above, if you are exploring a bay or inlet, that stuff all around you is most likely sedge.
Water Lilies are found in all still and slow-flowing freshwaters. One thing that I have noticed about them is that on any lake or pond, you will always find white ones, and usually also pink or yellow ones, but never both. The flowers begin in summer and last well into fall.
The launch point is on the river behind the little strip mall off Route 527 / Old Matawan Rd. I have never had a problem parking here, although I don't think this would be a good place for a large group to show up. Entry can be messy if the water is low.
The river is tidal and brackish at this point. If the tide is high, you can go upstream to the left, under the highway. Pick your way around all the fallen trees and have fun avoiding all the dead-ends, and you can go all the way to the Duhernal Lake dam. The lake itself is off limits.