IDing Elodea?

I needed to add some plants to my aquarium to help suck up nutrients to battle algae and bought some "Anacharis" which I assumed was Elodea canadensis and what I wanted as it is native to Ohio. Now that I look at it I am not so sure that it isn't one of the non-native look alikes. So how can I tell what kind I have. I have done an internet search and all that I can find is the native plants have 3 leaves per whorl and the non-natives have more. Sound right? or are their other ID characteristics?

Andy

In general, Elodea sp tend to have leaves arranged in 3, Egeria sp - 5, Hydrilla sp - 5.
There are so many exotics floating around, that sometimes when searchig for plants in a stream, all you find are exotics...

This website by Texas A&M is an interesting one and may help you (or anyone out) for future reference.
Texas A&M Aquatic Plant Identification Index

Pet shop anacharis is usually Egeria densa, at least in my experience. Pond suppliers seem to carry Elodea canadensis more often.

Edited by Newt, 14 April 2009 - 08:50 PM.

Here's an ID key from Alan Weakley's Flora of the Carolinas and Virginia, available for free download here:
http://www.herbarium.unc.edu/flora.htm


Hydrocharitaceae with Leaves in whorls along the stem....3

3a Leaves in whorls of 2-3 (no whorls with > 4 leaves) ................................................................................
...............Elodea
3b Leaves in whorls of 3-8 (some or most whorls with 4 or more leaves)....4
4a Leaves mostly 2-3 cm long, finely toothed with slender, weak teeth on the margins and rarely also the midrib
beneath; fresh leaves not noticeably rough to the touch; leaf whorls generally crowded on all stems; petals white,
9-11 mm long............................................................................
...................................................................... Egeria
4b Leaves mostly 1-2 cm long, toothed with stout, sharp teeth on the margins and also on conical bases along the
midrib beneath; fresh leaves noticeably rough to the touch; leaf whorls crowded on terminal portions of stems,
remote on older stems; petals translucent, 2-5 mm long ................................................................................
Hydrilla

Other references ive seen say that Egeria leaves on the lower and middle portion of stem are mostly in whorls of 4, while Hydrilla are mostly in 5's.
Both can have more leaves per whorl on upper stem near the water surface. In soft water Hydrilla doesnt always get the distinctive scratchy feel that Alan describes. Some states may also have Lagarosiphon (African elodea) - not yet invaded in the Carolinas, and not in this key.

In general, Elodea sp tend to have leaves arranged in 3, Egeria sp - 5, Hydrilla sp - 5.
There are so many exotics floating around, that sometimes when searchig for plants in a stream, all you find are exotics...

This website by Texas A&M is an interesting one and may help you (or anyone out) for future reference.
Texas A&M Aquatic Plant Identification Index