# Ludwigia and possible Rotala, emersed ID



## davemonkey (Mar 29, 2008)

I found a couple plants that look fun to try but I'd like to get a positive ID on them first.

First 3 pics are the _Luwigia sp_. Leaves alternate, stem very squared, flowers are the typical large yellow-4-petaled flowers...looks like 8 stamens (the blooms fell off by the time I took these photos). Capsules are long tubes, but not too long. Stems formed somewhat of a bush and were erect and strudy.

Next 3 pics are what I thought might be _Rotala romasior _(not sure if I spelled that corectly). The only thing is that these stems were more decumbant than erect and they were rooting along the stem wherever it touched the soil.

Can anyone provide a postive ID on these 2 plants?


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## khanzer22 (Nov 30, 2009)

Looks like Rotala ramosior to me as well...


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## Cavan Allen (Jul 22, 2004)

Looks like _Ludwigia leptocarpa_ (presumably, the petals have fallen off) and _Rotala ramosior_. Rooting at the nodes is not unusual for the latter.

http://www.southeasternflora.com/view_flora.asp?plantid=207#


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## davemonkey (Mar 29, 2008)

_L. leptocarpa_ has 5 petals though on the bloom. The one I collected only had 4. I noticed a bloom opening up tonight before I left the office (the stems are in a water bottle right now so that are staying hydrated). When I get back in the morning I'll snap a picture of it, and try to get a better shot of the stem and leaves. I was wondering if it might be _L. decurrens_, but I didn't notice any "wing" that the description mentioned...maybe I'm not understanding it right.

Anyway, if the bloom is still there tomorrow AM, I'll post a pic of it.

Here's a description I found just now...if this is correct, that is called "winged" due to the square stems having the wings (I am presuming that means along the entire length of the stem and not just a flag here and there) then I bet this is it. http://plants.usda.gov/plantguide/pdf/pg_lude4.pdf


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## Cavan Allen (Jul 22, 2004)

I should have asked if the stems and fruit are pubescent or not. Are they?


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## davemonkey (Mar 29, 2008)

They are pubescent. Hairs are extrememly short though...hard to se with the naked eye but they show up clearly under a 10x lens.

That fruit capsule is just under 1.5" long.

The flower did not survive the night. It has falled apart in the bottle, but definitely 4 petals.

Give me about 5 minutes...I'll post a more detailed pic of the stem and the friut...

Detail of fruit:









Detail of stem...note the 'squareness'. The hairs are hard to make out, but they show clearly under a 10x lens:


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## davemonkey (Mar 29, 2008)

I finally had some time to read thoroghly through Godfrey and Wooten. Their description for _L. octovalvis_ fits very well.

I looked it up on the Florida plant site and it seems to match.
http://florida.plantatlas.usf.edu/Plant.aspx?id=956

Has anyone ever tried that species?


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## Cavan Allen (Jul 22, 2004)

I think you're probably right. Definitely not decurrens, at least, which is glabrous. I looked at some octovalis specimens the other day and they seem to be quite variable in terms of leaf shape. Fruit looks about right as well.

I have never tried it submerged. All _Ludwigia_ of sections _Dantia_ (brevipes, repens, etc) and _Microcarpium_ (glandulosa, pilosa, etc) have worked, even if some of them don't look so hot (simpsonii, linifolia). We did try _L. alternifolia_ from section _Ludwigia_ (I think), but that doesn't work. Can't hurt to try though.


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