umbellet

from The Century Dictionary.

• noun A little or partial umbel; an umbel formed at the end of one of the primary rays of a compound umbel; an umbellule. See cut under Osmorrhiza.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A small or partial umbel; an umbellule.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a secondary umbel in a compound umbel such as the carrot; an umbellule