Gardening and Horticulture - Weed Identification and Control

Hello,
I am having a huge problem with a certain weed spreading in my lawn. This weed will grow eight to ten inches tall in places if left without cutting. It has an unusual cross shape with three sprouts coming out of a central seed ball. Does anyone know what type of weed it is, and what herbicide I could use to exterminate it?
For size reference, the grass in the photos is St. Augustine.
Thanks for you help!
CJ
http://i302.photobucket.com/albums/nn113/cj12101/Grass/picture3154.jpg
http://i302.photobucket.com/albums/nn113/cj12101/Grass/picture3148.jpg
http://i302.photobucket.com/albums/nn113/cj12101/Grass/picture3149.jpg
http://i302.photobucket.com/albums/nn113/cj12101/Grass/picture3150.jpg

Nut sedge is invasive and difficult to control. Yours looks more like yellow nut sedge than purple nut sedge. There are pre and post emergent treatments for yellow nut sedge. http://pubs.caes.uga.edu/caespubs/pubcd/C867-9.htm

Sorry for my delayed reply. Thank you for your response. The guy at my local nursery told me pretty confidently this is a species of sandbur. I meantioned I've been told it may be a sedge, but he said sedge has a triangular stem, while this one is just slightly folded. Does it possibly look like sandbur to you?
Thanks,
Carter

I landscape during the summers when school is out, and I have always known that as nutsedge. Honestly, send a picture to any university botanist (google search) and you should get a reply. I would like to know for sure myself.

Yellow nut sedge has a v-shaped leaf pressed along the vein.
Stems are triangular in shape. Seed heads are on triangular stems.

http://www.topturf.net/nutsedge.jpg

http://www.topturf.net/yellow-nutsedge.jpg
Photo Credits: Top Turf

Well, you're right that it's some kind of sedge. I think I've narrowed it down to Green Kyllinga. Check out the photos at this link. It's exactly what I've got. Doesn't sound fun to try to exterminate...
http://www.ppws.vt.edu/scott/weed_id/kylbr.htm