If it has thick succulent leaves, it may be wild purslane.

Thanks for replying, Sylvia. I've never seen any purslane in Texas, but I saw plenty of it in California. The leaves definitely are flat and 'leafy', and not fleshy like succulents. I googled a lot of images of 'wild purslane' and see that purslane leafs tend not to have pointy tips.

The stem or root network reminds me of purslane, but it is not. In fact, combined with that runner network and the leaf shape, I wonder if they might be more in some family like the wandering jew plants.

I agree that if not purslane, then perhaps a wild tradescantia. How does the foliage compare to this one?

Thanks, purslane and PK. I'll do some more Googling on wandering jew varieties, but on first glance (at the pic PK posted), I don't think so. My weed's leaves are more elongated. I just zoomed in on my Pic 2 and noted a characteristic hairs (?) along the edges; the WJ leaves appear smooth. Also, particularly on the neighbor's side, my weeds have been largely left untouched (no one weeds and the bi-weekly mows wouldn't even touch these weeds so close to the ground). These plants show no signs of mounding/clumping nor any vertical growth. Seems like only lateral movement.

What I may do is plop some into a pot and see where it goes. :)

It reminds me of doveweed, Murdannia nudiflora. Your leaves look broader though but there could be some variability. Might check that one out.

Maybe the related Commelina/dayflower? It has hairy stems.

Some tradescantias are hairy (like T. sillamontana). However, I agree that the plant in question does not seem to be a tradescantia.

Omar

Thanks for the input, misti and annie. Interestingly, a search into Murdanna nudiflora led me to this pic of Commelina erecta:

The leaf shape is similar, and this also has the red spots. None of the runners on my weed ever appeared above ground, however -- they pretty much travel beneath the soil surface (and we haven't gotten that much rain lately -- and none torrential -- that would have washed an entire swale's worth of soil over these plants.

The sun's shining on that part of the house now, so I'll see if I can discern anything new.

Thanks again to everyone for taking the time to post!

A couple of close-ups from just now. I've planted this into a 4" pot, so we'll see if it flowers and provides more clues.

bostedo, I do believe you nailed it! Sure does appear to be the dreaded VA buttonweed. Boy, am I up against a beast. Said swale provides all the perfect conditions for VAB to absolutely thrive, and there's not a whole lot I can do about it...I don't much feel like weeding the neighbor's side of the yard, so I'll just have to keep an eye on this. Thanks!

ETA: ...and I'll be yanking that sucker I planted in the pot -- no way I'm gonna encourage these, not one bit. :)

But, but...it has pretty flowers! ;D

Omar

But(ton), but(ton)...who's got the button?

Tell you what, Omar: IM me your home address and I'll gladly send you all future plantlings I yank up so you can have all the perddddy flowers you want! ;)

:D I’ll pass this time, javiwa. I thought (and so did you) it would look good in your yard.

Omar

Javiwa, Harvey brought all kinds of new plants/weeds in my garden. I always get a few VA creepers but this year I’m pulling hundreds. And about wild purslane, I get lots of it in late summer

Knock wood, bossy, but I might have had a few purslane pop up in one bed decades ago, but none since. Yeah, DH and I find ourselves saying "ever since Harvey" quite a bit lately. Man, the dichondra has absolutely gone nuts in every stretch of St. Augustine -- don't know if I can blame that on Harvey, but I just don't ever remember it being this widespread.