Thanks, dchall -- I try really hard never to allow any weeds to go to flower (not always successful, but I try). Given how widespread this got, I'm not detecting any budding/flowering at all -- is that even possible? Some of the 'older' patches had actually started to yellow/brown and go dry -- no flowers.

We live in SW Houston. During the summertime, DH mows at the highest level (so, 3"?). We had so much beneficial rain once a week last spring, the sprinklers never went on. During summertime, we've got the zones set to 60 minutes twice a week -- starting 4 a.m.

It's not as though we've had much of a winter this year -- I think we woke up to less than a handful of mornings when there was visible frost on the neighbor's rooftops. But the grass has definitely slowed to a point where DH is mowing only a couple of times a month -- I don't think he's lowered his mower.

I also have this in my lawn. I think it is one of the types of sedge - maybe carex texensis? There are other types which are similar, but in any case, it is much nicer than the nutsedges, in my opinion. Here is one of many webpages on this sedge : Texas sedge

Thanks, plantloverkat -- that could very well be it. However, it gave me quite a giggle that this is intentionally planted by some and has bona fide landscape uses! :D Oh, well....one person's weed is another person's, well, you know.

ETA: agree...nutsedges drive me nuts! hahaaaaaaa!

I managed to snip these before DH mowed:

I did more searching (starting with Texas sedge -- thanks, plantloverkat!) and stumbled on what I think is the culprit: kyllinga. NCSU's website pic is a perfect match:

If not opposed to chemical treatments, the growing number of turf-safe sedge-targeting herbicides can be pretty amazing on those resilient patches that no amount of pulling or digging seems to eliminate. This article from UTn includes a good table of some leading options: Nutsedge and Killinga Species.

Thanks for the link, bostedo -- very helpful. Sedgehammer...heh. :)

I may hit the local BigBox for Image, as that product seems fairly widely available. I spent another 5 hours in the yard yesterday, and to date have probably hand-pulled enough to fill a 5-gallon bucket. At least the weather's been nice!

Yes, it is a nut sedge. You have to dig down to get the nut rather than just pulling it out. I fought it all summer last year. The Image didn't seem to phase it so I found that digging it out was the most effective. Sedgehammer may work better but it was not available locally and I didn't bother to order it online after the Image failed. So far it has not come back as thick this year.

Sedgehammer apparently is not reliably effective without adding the recommended nonionic surfactant. Sedgehammer+ (SedgehammerPlus) includes the surfactant and is the version now most commonly sold in retail quantities. That's what we've used and found very effective at killing nutsedge down to the nuts. Though might not be as good on killinga according to UTn.

It has a short shelf life once mixed and produces a slow kill. So we mix only half a pouch at a time to get at least two fresh treatments for any well established clumps. Has eventually killed every nutsedge we've used it on where pulling, solarization, or glyphosate failed and digging missed too many. Not familiar with Image, but wonder if it shares some of the same usage peculiarities.

Thankfully, our nutsedge issues are minor and confined to our beds -- annual mulching keeps those checked.