Answer: Catnip is a member of the mint family and all members of the mint family have square stems. There are weeds with leaves similar to catnip, but without the square stems. Some can cause itching in sensitive individuals. I think you've found stinging nettle. The hairs on the leaves come off on your hands and skin when you touch the plant and can cause a numbing, itching and burning. The best solution is to cut the weeds down to ground level as soon as they appear. If you keep the plants from flowering and setting seeds you go a long way in controlling it!
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