Hello: These “growths” are growing on one of my allium flowers. Any idea what they are?
Dear gardener, I am so sorry but I am totally stumped by your question. The closest I got is that it is either a seedpod, a bulbil (a small bulb), or a wasp gall.
I did find a photograph online of an allium with a three-chamber green seedpod with little black seeds in each pod. However, each of these individual seedpods is tiny, and each seedpod is at the end of one of the multiple stalks (pedicels) that make up the flower umbels.
It looks from your photograph that the growths are at the base of the umbel, and at the top of the peduncle (stalk of the inflorescence), which makes me think yet another explanation is closer.
Alternatively, it could be a bulbil. Some alliums (Allium roseum, A. sphaerocephalon, and A. vineale) produce aerial bulbils (small young bulbs instead of flowers) in the flower head. Here is a photo.
A more likely explanation is that the growths are galls created by a small wasp midge that is now a parasite on your allium. I would cut off the gall and dispose of it, rather than composting it.
You could determine which it is, by cutting through the pods and finding either the seed, onion, or a midge. Sorry that I am not more helpful.