The Center for Aquatic and Invasive Plants (Univ of Florida),
http://aquat1.ifas.ufl.edu/ has excellent photographs and line drawings of
lots of native and invasive water plants, wildlife, birds, etc. The line
drawing comparison of hydrilla, elodea, egeria is good for determining which
plant is growing in your pond.
--
Zk

"Cichlidiot" wrote ...

Yep, they can get flowers. And the differences between the Elodea and
Egeria species are in the structure of the flowers, although I can't
remember the exact differences now ...