Umbellules

An umbellule is a small umbel, a secondary inflorescence or subunit within a plant’s overall flowering arrangement that resembles a tiny umbrella. The term is used to describe a cluster of flowers whose pedicels radiate from a common point on a short axis, forming a compact, umbrella-like head that is smaller than a typical umbel.

Morphology and arrangement: In an umbellule, the flowers are borne on pedicels that originate from the end of a short stalk or a branch, producing a localized, umbrella-shaped grouping. Umbellules can be solitary or multiple within a larger inflorescence and may occur as a secondary or even tertiary level of branching. The rays (or spokes) of an umbellule are shorter than those of a full-sized umbel, contributing to its dainty, dense appearance.

Occurrence and taxonomic usage: The term is most often encountered in descriptions of Apiaceae (the carrot family) and related groups, where compound umbels are common. In such plants, an inflorescence may be described as comprising a main umbel with one or more umbellules at the ends of its rays or along its branches, providing a nested, umbrella-like display.

Etymology and distinction: Umbellule literally means “little umbel.” It is distinguished from a full umbel by its smaller size and subordination within a larger inflorescence, though some sources use the terms umbella, umbeller, or umbellae to describe similar small umbrella-shaped units. The exact usage can vary among botanists and floras.