From the primary floral axis a the secondary axes come off in a radiating or umbrella-like manner, and end in small umbels b, which are called partial umbels or umbellules.
- Compound umbel of Common Dill (Anethum graveolens), having a primary umbel a, and secondary umbels b, without either involucre or involucel.
Again, there may be a raceme of capitula, that is, a group of capitula disposed in a racemose manner, as in Petasites, a raceme of umbels, as in ivy, and so on, all the forms of inflorescence being indefinite in disposition.
Raceme of Umbels, Ivy.
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.