'qt', you know the ferny-looking foliage on the carrots at the supermarket? Well, first you will see some kind of very thin long leaves and then a tiny fern-like leaf will appear. After awhile, there will be more and more of the fern-like leaves. But first, there will be those 2 thin, strap-like seed-leaves that don't really look ferny at all.
An onion seedling will come up with one leaf. It will be bent and a rather odd-looking thing because the tip will still be trapped in the soil. After a few days, the tip will spring loose and the little thing will point straight up in the air. They are almost as skinny as dog hair - green, dog hair.
Steve