HeyPK

From a distance it looked like L. palustris, but then I spotted the big flower. The USDA map does not show L. aucuata in Mississippi, but it is shown in Alabama just to the east. It was in a ditch quite near my home in Madison, MS, just north of Jackson.

Tex Gal

Another example of a COMPLETELY different emersed form. It never ceases to amaze me!

Cavan Allen

Are you sure that's L. arcuata Paul? It kinda looks like L. peploides.

HeyPK

Nope! L. peploides is also common around here and is a much bigger plant and does not have lots of side branches coming from the main stem like this one does. I picked some of this putative arcuata and will float it in a tank and see if I can get the submersed form.

Two pictures of L. peploides

Cavan Allen

You still have that article, right? Can you key it out?

Phil Edwards

I agree with Cavan, the first photo looks a lot like the L. peploides we have here in GA and what I've seen in NC. Looking at the flower, it appears there are 5 petals rather than the 4 [i]arcuata[/] has.

Here's the description of L. arcuata from Godfrey and Wooten.

Perennial, branches prostrate and creeping, rooting at the lower nodes. Stem pubescent with short, hooked hairs, these sometimes shed on older portions. Leaves opposite, sessile, oblanceolate or some of them narrowly or broadly elliptic, the 3 shapes not uncommonly on a single plant, mostly 8-20mm long, sometimes glabrous, sometimes minutely scabrid on and near the margins and with hooded hairs on the midrib beneatl. Flowers solitary in leave axis, usually only in the axil of one of the pair of leaves at a given node and relatively few nodes bearing flowers at all; flower stalks slender, markedly longer than the subtending leaves, sparsly closed with short, hooked hairs as are the floral tubes and outer surfaces of the calyx segments; bractlets narrowly oblanceolate, 2-3mm long, opposite or subopposite just below the floral tube or distally on the flower stalks. Calyx segments 4, elongate-triangular, 4-8 mm long. Petals 4, bright yellow, obovate, somewhat longer than the calyx segments. Capsule obconical in outline, obscurely quadrangular, usually curved, 6-8 mm long.

HeyPK

I am agreeing, too. However, the plant looks quite different and much smaller than the local L. peploides growing in the same ditch. When I get some time, I will get both plants together to do a comparison picture.