# Two Heteranthera species in central Mississippi ditches



## HeyPK (Jan 23, 2004)

They look as though they are related to _Eichornia crassipes_, the water hyacinth, but they turn out to be _Heteranthera_ species, and there are two of them. The first is, I think, _H. reniformis_:









This species has multiple flowers on a stalk. The other plant in the picture is Ludwigia peploides:









The other species has single white flowers. It could be _H. limosa_, which usually has blue flowers, but is also shown in a number of pictures with white flowers. Or, it could be_ H. rotundifolia_, which, on the USDA plant database, is west of Mississippi but not in Mississippi.


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## davemonkey (Mar 29, 2008)

*Re: Two Ditch Heteranthera species in central Mississippi*

Awesome! We have _H. limosa_ here in SE Texas as well (at least in the coastal counties) and I've only seen them with blue flowers. They also seem to stay quite small (compared to other wetland plants like burheads and pickerel weed).


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## Noto (Oct 26, 2009)

Nice! For what it's worth, the few _H. limosa _I've seen blooming in TN have had white flowers.


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## PeterE (Feb 9, 2010)

Great pics! Both look like attractive species.


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## Tex Gal (Nov 1, 2007)

The heart-shaped leaves are adorable. What is the size? Does the submerged growth look the same?


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## HeyPK (Jan 23, 2004)

The H. reniformis can have leaves two to three inches across with petioles up to six inches long. The floating plants in the first picture were smaller with leaves an inch or so across. I suspect that the submerged growth would have strap-like leaves. 
Update: They sprayed the ditch with roundup, and all the visible growth of the white-flowered species was killed. Hopefully, they didn't get all of it, and the species can make a comeback. It is a nice ditch for other aquarium plants, such as _Echinodorus cordifolius_. I don't know why people hate plants that grow in ditches. The ditch was so much prettier when it was all green and the plants were flowering. Now it looks all brown and dead.


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## HeyPK (Jan 23, 2004)

The white-flowered Heteranthera species is coming back! They sprayed the ditches and they also used a weed eater before they sprayed. The plants that were not cut down with the weed eater were killed entirely by the roundup, but the plants that were cut down got such a small dose of the roundup that they are putting out new leaves. Yea! Nature, 1. Stupid anti-nature people, 0.


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## HeyPK (Jan 23, 2004)

Update and major correction!

The white flowered species, I am now convinced, is not Heteranthera at all, but _Limnobium spongia_. I should have recognized it by its flower, which has too many petals to be Heteranthera.


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## miremonster (Mar 26, 2006)

Hello Paul,
nice to see real Limnobium spongia! The name is often in aquarium literature, also erroneously for L. laevigatum in the trade, but it seems to me that this species is nowhere cultivated in Europe.


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## Cavan Allen (Jul 22, 2004)

I saw it in Vermont one time.


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## miremonster (Mar 26, 2006)

Hello Paul & Cavan,
but now looking at the pics again I'm in doubt with Limnobium... There are young leaf blades wrapping the petioles of the older leaves, as in Heteranthera and other Pontederiaceae but not in Limnobium (AFAIK).
@Paul: Could You make a closeup pic of the leaf venation? Heteranthera: many fine nerves parallel to the midrib, connecting nerves hardly visible. Limnobium: few spaced parallel nerves on each side of the midrib, between them distinctive connecting nerves => grid-like pattern, as in Alismataceae, Apono- or Potamogeton.

-Heiko


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## HeyPK (Jan 23, 2004)

I think you are right, Heiko. I can't see cross veins, the leaves emerge from a sheath around the stem, and the plant does have prostrate stems, whereas Limnobium appears to be a crown plant with runners. Also, the flower has 6 petals, which is consistent with other Heteranthera species. Best guess is _H. limosa_. Many, but not all pictures show _H. limosa_ with narrower leaves and blue flowers. Some pictures, however, show white flowers.  
This is an enlargement of my picture.


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## miremonster (Mar 26, 2006)

Hello Paul,
I've looked in FNA, the broad leaves and white flowers seem to be in line with H. limosa:
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=115266
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101660


> blade oblong to ovate, 1-5 cm × 4-33 mm, length equaling or greater than width; base truncate to cuneate, apex acute.


Though it isn't known from Miss.: Can _H. rotundifolia_ be excluded, based on the key and description in FNA?


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## HeyPK (Jan 23, 2004)

Miremonster said:


> Though it isn't known from Miss.: Can H. rotundifolia be excluded, based on the key and description in FNA?


The differentiation between the two species in FNA's key seems based on when the stems begin to elongate. It is always for rotundifolia unless it has been emersed at an early age, but only happens if the plant is in over 5 cm of water for limosa. That sounds like a hard one to check out. And, just what is meant by elongation? The leaf descriptions seem to favor that I have _H. limosa_. There are no cordate leaf bases. (See picture in first post.)

The other thing is flanges on the central lobe of the perianth. I will have to wait until this summer when the plants are blooming to check that one. Hope they don't spray the ditch too often! From what I have seen, however, all six of the petals of my plant are the same. (To be botanically correct, I should say all six of the tepals are the same, since the sepals and petals look the same, and they are called tepals when they are like that.)



FNA said:


> Vegetative stems commonly elongating unless plant emersed from early age; petiolate leaf blade round to oblong, base cordate to truncate; distal central perianth limb lobe with lateral flanges 5 Heteranthera rotundifolia
> +	Vegetative stems elongating only on plants in over 5 cm of water; petiolate leaf blade oblong to ovate, base truncate to cuneate; distal central perianth limb lobe without lateral flanges 6 Heteranthera limosa


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## miremonster (Mar 26, 2006)

OK, then it's most probably H. limosa indeed. In the description I've overlooked these lateral flanges on the perianth lobes, that seems to be a good distinguishing feature, hopefully they will flower before spraying.


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## HeyPK (Jan 23, 2004)

This summer, I am going to have to get up earlier than I am accustomed to to get a picture f the flower before it wilts. :ranger:

I found this picture, which shows a plant looking very much like mine. The picture was at this link:http://florasilvestre.es/mediterranea/index.htm


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## miremonster (Mar 26, 2006)

I was not aware that Heterantheras occur introduced in South Europe! 
This H. limosa in Spain has a slightly cordate lamina basis...


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