I can't narrow down the top one besides to say I believe they are in the sedge family. Slice through one of the stems under the seed head and check to see if it is roughly triangular in shape. That would verify it is a sedge. The solution for sedges is different from that of grasses or other plants. In the US we have a product called Sedge Hammer and one called Image. Don't know what you might have behind the black stump. For the other weed my first approach would be to use a 2,4-d product. Do you have Weed-B-Gone? The idea for these sprays is to moisten the leaves of the plant, not to drench the soil. A little goes a long way. If the second plant is not killed by the Weed-B-Gone, I would try putting some RoundUp in a small bud vase and sticking a strand of the plant into the vase. Let it soak up the RoundUp. There are some vine type weeds where one root system feeds a lot of the plant. This might be one. I've tried it on bind weed in my garden. One vase killed all the weed in the garden.

Oh, so it really is nutgrass? I had nutgrass a couple years ago, but I was able to eradicate it until now. I just didn't identify it since the appearance of this weed is different from what I was familiar with. I thought nutgrass was identified by its tall, long, and thick yellow blades; however, from what I can tell, this weed doesn't meet any of that criteria. I assume the small green balls are actually the flower? Mine haven't bloomed yet, but this picture I found on Flickr seems to be the closest to what I have: http://www.flickr.com/photos/97769244@N00/1347478544/ Also, shortly after I posted, I found another plant called Sparganium which bears a striking resemblance to the current appearance of my yard. Here's a pic: http://www.pwrc.usgs.gov/history/herbarium/sparganium_americanum.jpg However, it appears to be an aquatic plant, commonly found in wet areas. I have no idea how it could have gotten into my yard, or how it would even survive in my dry, full-sun soil.

That is torpedo grass, very tough invader. Unfortunately not many options are effective. Of course roundup works, as does pulling, but it will continue. Apparently the Florida DOT hits it with a torch, then glyphosate with good success rates. My neighbor has also had some success with Drive XLR8

Keep that away from me and nuke it from orbit. It's the only way to be sure. Tenacity will take it out, although it'll also bleach PR/Fescue and may do damage to both as well depending on the cultivar (it is listed for turf type tall fescues and perennial ryegrasses, I've simply noticed it seems to do a little more damage to them than it does to bluegrass, although they certainly do recover from it). Several applications, several weeks apart, may be necessary to control it, and it's a prolific seeder, so it'll be back. Use of any good pre-emergent listed for P. annua (I like Prodiamine, but many others work as well...including Tenacity itself, which is a short-term pre-emergent of about 30 days) helps to suppress the seed sprout. P. annua is a fall-sprouting grass, just like any other, and easily survives any northern winter (it's now naturalized itself to friggin' Antarctica as per an arcticle...I mean article I read some years ago). Use of most pre-emergents will preclude reseeding your lawn since it sprouts at the same time and under the same conditions as your lawn grasses do, but Tenacity application with the lawn seeding will help you out there. It's not perfect, but it helps. The instructions are on the bottle.