I had two plants like this grow from seeds of 'Ailsa Craig' onions. One was very small and never did much, while this one grew very well.
It has no bulb at all, goes straight down to roots--it looks rather like a leek from the small one I pulled up. Instead of one stalk, it has many. As I said, this one was one seed this spring, and there are at least ten? stalks now. Also, it hasn't dried down like a normal cooking onion, it's still green and growing.
It's fun to go out in the garden and have those "Huh, what IS that?" moments. But this is frustrating because I can't find the seed packet the Ailsa Craig came from, and so don't know the company. I only planted maybe three dozen of the AC, so this was either a big coincidence to get two of those plants, or there was a large percentage of the odd seed in the packet and the original grower might have had an idea what it was. And I always keep every seed packet . . . Grrr.
Anyway, I may do like you suggest and see what happens next year. The base is maybe five or six inches across, so something might want to break lose without too much damage. Thanks for the reply! I sure appreciate it.
i would just call it a bunching onion and divide it up in the spring and eat what looks good. onions will cross pretty easily if there isn't enough distance between them to discourage the bees. the bees here love the chives and bunching onions and the other regular onions if i let them bloom. i planted some old seeds expecting not much to grow and now have a fine looking green hairy line in the garden i'm going to have to weed and thin out at some point. or if i leave them they can see if what will persist and survive through the winter and then i can try to deal with it in the spring. hmm, i like that plan better.