locules

Locule (plural locules) is a botanical term for a cavity or chamber within a plant organ, most often the ovary or the fruit, and less commonly within an anther. The word derives from Latin loculus, meaning a small place. In ovaries and fruits, locules are formed by internal walls called septa that subdivide the space.

In an ovary, the number of locules reflects the degree of carpellary fusion. An unilocular ovary has a single locule; a multilocular ovary contains two or more locules. In syncarpous ovaries, multiple locules arise from fused carpels; in apocarpous ovaries, each carpel typically forms its own locule, so the locule count can correspond to the number of carpels.

Locules contain the ovules or seeds and are often visible in cross-sections of mature fruits. The arrangement of locules is closely linked to placentation and fruit structure; many common fruits show distinct locular segmentation, such as tomatoes, peppers, and citrus, where seeds or juice sacs occupy the locules.

In addition to ovaries and fruits, the term locule is also used for compartments within anthers (locules or thecae) that hold pollen sacs. The concept of locules is a key descriptive feature in plant anatomy and helps characterize fruit types and reproductive morphology.

See also: unilocular, multilocular, septum (botany).