Umbel synonyms

The tufted head or umbel is likened by Pliny to a thyrsus.

At the base of the general umbel in umbelliferous plants a whorl of bracts often exists, called a general involucre, and at the base of the smaller umbels or umbellules there is a similar leafy whorl called an involucel or partial involucre.

When the axis is so shortened that the secondary axes arise from a common point, and spread out as radii of nearly equal length, each ending in a single flower or dividing again in a similar radiating manner, an umbel is produced, as in fig.

- Compound umbel of Common Dill (Anethum graveolens), having a primary umbel a, and secondary umbels b, without either involucre or involucel.