Noun
A kind of flower cluster in which the flower stalks radiate from a common point, as in the carrot and milkweed. It is simple or compound; in the latter case, each peduncle bears another little umbel, called umbellet, or umbellule.
Source: Webster's dictionaryA. ×proliferum, tree onion The tree onion or Egyptian onion produces bulblets in the umbel instead of flowers, and is now known to be a hybrid of A. cepa × A. fistulosum. Source: Internet
The inflorescence takes the form of a globular umbel of white flowers with parts in sixes. Source: Internet