Webster's Revised Unabridged Dictionary · 1913

Water grass

Water grass

(a)
A tall march perennial grass (Paspalum dilatatum) of the southern United States and the American tropics.
(b)
Manna grass.
(c)
The grass Chloris elegans.
(d)
Velvet grass.
The water cress.
One of various horsetails. [Dialectal English]