ACtually this may help. The first two photos were of growth that had a relatively broad blade. Here is a picture of another patch of the lawn which has much narrower blades. I am assuming given all areas of the lawn have had equal growth conditions, this patch is something different than the above pictures. Could this be Rye?

The nuts can lie dormant in the ground for several years, so even when you think you've got it gone, it can reappear. This is one that requires absolute diligence, but, with diligence, you can conquer it. The chemical is called Image. I pour a bit into a paper bowl, wear a disposable plastic glove, dip my gloved hand into the bowl and then "run my fingers" through the blades. Wait a week and if the leaves don't look sick, do it again. Two applications nearly always works. By applying it this way, it's unlikely you will get the chemical on anything else. Still, Image is supposed to be safe for use on most ornamentals...If you have a big patch, you will have alot to do at first, but as the season progresses, it gets easier, and usually by year three, you have it completely conquered. BUT if you let off the pressure, those nuts will run under ground and reproduce like mad, landing you right where you started. Grrrr. The alternative is moving your garden.... Oh, and yes, I have a friend who conquered a patch of it by pulling it daily until it gave up the ghost. I guess it depends on how much time/money you're willing to spend.

If all you have are grasses...maybe check out Imazapic. There has been some conflicting info on it's affect on native forbs. So do your research first. It is used in Cotton and Peanuts in Florida and in Prairie or CRP management in other states.... Info is under the heading: Weed Management During Establishment Establishing Prairie Plants for CRP and Wildlife Habitat http://ipcm.wisc.edu/uw_weeds/extension/articles/prarplntcrp.htm Also see the label.... Vera Here is a link that might be useful: Imazapic (Plateau) Label

Pulling tends to leave the 'nut' (actually a tuberous root) in place. And new plants will just generate from that root. But if you carefully dig up the entire plant, root nut and all, and before it is allowed to flower and seed you can pull/remove by hand and have pretty decent control. FWIW, this s a much easier practice to follow in a planting bed.....not so much in the lawn. And is rather time consuming!!