# ID puzzler, experts needed



## lampeye

Saw this yesterday. I think I know what it is, but I want your opinions. In the second photo, yes, there's a Ludwigia with it, but I'm asking about the more delicate-looking light green submerged plant. I tried, but found no flowers on any plants. 

















The punchline is...I'm in Pennsylvania. o_0


----------



## miremonster

I'm pretty sure that this is a Callitriche species. The swimming rosette-like shoot tops are characteristic of the most species of this genus. At least here in Europe there are many difficult to distinguish Callitriche spp., I don't know the ones occuring in the U.S.


----------



## lampeye

Danke MM. I think you put me on the right track. It would almost certainly be _C. palustris_. It just seemed so Didiplis-esque, except for those maddening surface leaves. And I would expect to see lots of flowers in the leaf axils. The location would be ALL kinds of wrong, though. But Callitriche would make perfect sense.


----------



## Tausendblatt

WOW, now I know I am wrong as to the species of callitriche I have...


----------



## lampeye

It could be _C. stagnalis_, but I would need flowers or fruit to make the ID positive. There are only three aquatic _Callitriche_ in PA, according to the only reference I have, and it does not resemble _C. heterophylla_.


----------



## Cavan Allen

What part of Pennsylvania?


----------



## armedbiggiet

can i find this in the market? never hear any one have these. If PA can have it MD should too.


----------



## lampeye

Southeastern PA, near Quakertown. Found some of what MIGHT be _Samolus_, too. This would be a good spot for a DVAGA excursion.


----------



## Cavan Allen

lampeye said:


> Southeastern PA, near Quakertown.


Thought you might be. I'm not so sure what you took a photo of is a _Callitriche_. _Elatine americana_ looks astonishingly similar submersed, and I'd wager that's what you saw (endangered in PA - only found in the extreme East and Southeast according to USDA). _Callitriche_ floating leaves are rounder and more numerous, and all species I've encountered (many in PA) are ephemeral, and only seen in the spring and early summer; it's almost guaranteed that they're gone by now. _E. americana_ may be found as small clumps growing emersed on the shore with typical _Elatine_ fruits; you might try looking there again for that. I contrast to _Callitriche_ species that die every winter (not all annuals do in culture), _E. americana_ soldiers on, unaware of the bitter cold outside your window.


----------



## lampeye

I'm hoping this might help a little more. Having seen photos of both, I'm still leaning towards Callitriche, but I have little experience with either, so...


----------



## Zapins

I think it goes without saying you should collect some, grow it, and spread it around the hobby  What better way of ensuring its survival?


----------



## Tausendblatt

Callitriche sp. are among my favourite plants! They are pretty darn variable, there are round leaves and narrow leaves on the same plant. They spread by seeds in the aquarium easily, and seem to grow from cuttings as well. I have medium light and have had no CO2 until yesterday, they all do fine. I dose NPK, iron, Mg, Mn, and Zn. Just FYI.


I could distribute some soon, but I don't think I have an endangered species. Callitriche are abundant here! They never seem to grow in water more than a foot and a half. But would they in captivity? My theory is they are just outcompeted if they cannot easily reach the surface. I haven't let mine reach the surface yet, and they are doing fine.


----------



## Cavan Allen

OK lampeye, you were right. I found some of this in PA a few weeks ago with mature fruit. It is _Callitriche terrestris_, an unusual one often found well away from water and, apparently, it's not quite so..ephemeral. As of now, it is totally indistinguishable from what we've been mistakenly called _Elatine americana_. Lesson learned, I suppose. I don't remember quite how we arrived at that ID (I believe wanting to get it out there and share it because it's such a great plant had something to do with it), but suffice it to say that the ID is corrected. I'm told that _E. americana_ is now considered synonymous with _E. triandra_, and a cursory examination of some specimens seems to support that.

I'm not sure why the pics in the PF are broken right now, but I'll get on fixing it.


----------



## HeyPK

In Fassett's Manual of Aquatic Plants, 1940, _Elatine _is differentiated into species mainly by the pits on the seeds, whether they are rounded or angular, and by the size and shape of the seeds, which can be seen through the thin walls of the fruit. You need a microscope. _Elatine_ does not form a rosette at the surface.










_Callitriche_ is differentiated on the basis of the fruits, their shape, size, whether or not they have a visible stalk and whether or not they have bracts.










I know that _Callitriche_ is fertilized underwater by pollen released into the water. Probably _Elatine_ is, too.

Fassett is still a fine book with excellent drawings. The college library was throwing it out because it was old, and I was lucky to find it in a pile of discarded books.


----------



## HeyPK

Here is a picture taken 3/19/04 of Callitriche in Mississippi forming rosettes.


----------



## Cavan Allen

Yes, it is by the fruit with _Callitriche_. The material we found had mature fruit that was distinctly short stalked and of the right shape and size. Some of it was a bit away from the water on a path by the river. Quite different from other species that are always in water and usually gone by July.


----------



## Noto

Curious. I see plenty of _Callitriche_ in Tennessee through August and September, and have seen the tiny terrestrial form on mudflats along Kentucky Lake during winter draw-down (October). I just collected some from a shallow sandy run in the North Fork Obion, haven't keyed it out yet.


----------

