Invasion of the mutant martian spear plant. . . .

This thing is just plain scarey looking. I have no idea what it is, but it's growing like a weed in the middle of the meadow where little else will grow.

Here it is in context. It looks like it would pierce your foot if you stepped on it. Another thing that I should kill while I still can, while it's still small? "Small" being a relative term here. . . .

Speaking of killing small plants, though, I think the tomatoes are toying with me. They have not grown a bit since the last picture posted. Perversely, now I want them to survive! Maybe they heard my earlier threats and are on strike. I'm sorry, little tomatoes - please grow!

Now back to our mystery: does anyone have any idea what this pointy plant is?

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UPDATE [Thursday, 04.16.09] - seen on king's to-do list: "Kill mutant martian spear plant"