I thought it might be a Portulaca but couldn't find any with the same flowers. Maybe this probably wrong suggestion will spur something in someone's memory.

Bacopa monnieri shows some resemblance.

http://luirig.altervista.org/s...

http://www.wildflower.org/plan...

I found something else which was similar but I don't remember what it was!

Arenaria was one I thought similar, if you can find a photo of Arenaria ludens ..

http://luirig.altervista.org/s...

http://www.nordaflora.no/arena...

http://www.naturamediterraneo....

My first thought was Purslane aka wild Portulaca, Pigweed, Pusley. The fat little paddle shaped leaves look right, and the flowers can be that big, but the wild ones are usually smaller. The unopened flower on the right looks like a purslane, too.

The hybrid purslanes you see at the garden centers have flowers in different colors incl. white that look like that, too. If you are near enough to find it again, taste one of the leaves. A juicy, slightly tart taste will seal the deal. (Purslane is a delicious and nutritous salad green.)

Not Bacopa monnieri, I am growing that at home.
Arenaria ludens doesn't grow anywhere near hear. No Arenaria are recorded in Galveston County, but the closest, Arenaria serpyllifolia, does not look like it.

If we could at least get a family that would help, I went through all the Portulacaceae but can't find anything close.

http://luirig.altervista.org/f...

I've also been through most of the Caryophyllaceae..

http://luirig.altervista.org/f...

And some of the Scrophulariaceae ..

http://luirig.altervista.org/f...

Also checked Aizoaceae ..

http://luirig.altervista.org/f...

Can anyone could suggest a family from this long list? It's relatively easy to search for those only found in TX.

http://luirig.altervista.org/s...

I don't know what to look for but the USDA plants database has more search options than I even understand, including limiting the results to a particular state.

http://plants.usda.gov/adv_sea...

Could it be a variety of Minuartia? http://www.google.com/search?q...

I started with Minuartia Lin but couldn't find anything with leaves like it.

Interesting plant! It seems obvious a succulent.

As far as I can see the flower, I suppose the plant belongs to the family Gentianaceae.

I am tempted to say it's Sabatia arenicola. A form with white flower which has developed a succulent appearance, more like I seen in pictures on the internet.
Plants that grow in the coastal marine sand frequently develop succulent habit, similar to the desert plants, because they have to face the same requirements to save fresh water.

Good eye Justin. I have also seen examples of coastal plants that grow more succulent leaves than the inland forms. I also found pictures of a coastal Sabatia arenicola that appears to have the same smaller more succulent leaves as in my photo. The only difference is the flower color.

http://www.wlf.louisiana.gov/f...

I think that may be it but I will leave this thread open for now just in case someone might come along with a better suggestion.
Hopefully I will be able to go back to that area again next year and see if I can get a better look.

Meanwhile I read other descriptions of the plant. Especially in older books is emphasized succulent appearance of the plant. Now I'm more sure of identifying plant above.

Jay if you can, I think it would be useful to display photos and the topic of family Gentianaceae. The thread "Gentian family - Family Gentianaceae" in Wildflowers forum

Even if identification is still questionable.
I don't found yet such photographs of the Sabatia arenicola showing succulent character of the plants, so good like yours.

Here a picture of Herbarium Specimen http://eol.org/data_objects/17... (click on image to see bigger)

I searched for Gentianaceae Galveston Island and found Sabatia angularis which can have white flowers, the photo also shows some pinkish marks around the eye which can be seen in the one in question .. leaves also look succulent. This was Galveston!

http://www.wildflower.org/gall...

Form albiflora has white flowers ..

http://en.wikipedia.org/wiki/S...

I don't think it is Sabatia angularis. That do not means I can't mistake.

What make me to say that the flower, presented by Jay, it is Sabatia arenicola was to observe the calyx.
Calyx lobe is short if we compare to the calyx tube and have more a triangular shape, that, how I read, it is caracteristic for the S.arenicola. (But I think in different conditions can be more or less obvious triangular shape). And the sharp raised ridges on calyx tube.

S.angularis have calyx with sharply ridges while S.angularis lacks ridges or have low ridges.


A page with good pictures for S.angularis
http://www.missouriplants.com/...


I think Sabatia arenicola is more close to Sabatia campestris. They have the calyx tube very similar, but the calyx lobes is different special if we compare the length of lobe relative to calyx tube length.

All this three species can have white flower form. But it is a rare form.

Bibliography

[1] A field guide to Southwestern and Texas wildflowers - by Theodore F.Niehaus, Charles L.Ripper and Virginia Savage; - The Peterson Field Guide Series 1984.
[2] Plants of The Texas Coastal Bend - by Roy L.Lehman, Ruth O'Brien and Tammy White; - Texas A&M University Press College Station, second printing 2009


On WEB pages
[a] Here

http://www.biodiversitylibrary...

on page 1315-1317 description of all these three species.

[b] Here

http://www.biodiversitylibrary...

interesting key to delimited some species of Sabatia (zoom for can well read or if somebody is more interested it can download like PDF )

----

Note

About image of S.arenicola presented here
http://www.wildflower.org/gall...

I don't know what to say about this picture. It is difficult to see the calyx. And the calyx lobes don't look for me like of S.arenicola.
But below on page it is mentioned that the image has not been verified.
And of course the plants depend very much of growing condition (A cultivated specie can look very different compare with really wild sisters)
If we look with attention to the picture on right the plant have a flower with 7 petals and in [1] (book mentioned above) it is write "always 5 petals" so it is possible the plant from wildflower.org it is not S.arenicola.