I started on these reeds about a month ago and got sidetracked making trees, so I'll post about them now before I forget again.
What's a body of slow moving water without some reeds?
I started out using some Woodland Scenics Light Green Field Grass.
Then I dipped that end in some Matte Medium and let it dry.
I trimmed the tops off to a length of about 1/2" even, later I cut a few at a slight angle so I would wind up with a few different lengths.
Using an exacto I split them into smaller batches.