Our garden has always (since we moved in 4 years ago) had a problem with this weed. It spreads like wildfire and is difficult to pull up (snaps level with soil). We had a lot of work done to the garden last autumn - new lawn, new play area for kids with membrane and play bark, new patio and path, etc. - and while it is better than before, the bloody stuff is coming back. Even pushing its way through the membrane under the bark. I think I've seen it called prairie grass before but anything online doesn't look like it (that I've been able to find anyway). Comes up with its "needles" tightly closed in looking like a kind of smooth shoot. Then when the "needles" unfurl it looks like tiny trees. It can get very tall if not pulled or cut back and seems to be able to push its way through lawn, shingle and membrane/bark. Any ideas what it is and how to get rid (short of napalm)? Thanks in advance.