Operculum (plural = opercula)

Title

Operculum (plural = opercula)

Definition

Lid-like; the lid of a dehiscent fruit as found in many, but not all, Lecythidaceae.

Notes

In Lecythidaceae, dehiscent fruits with opercula occur in Allantoma, the obliquely zygomorphic-flowered Cariniana, and most of the species of the other zygomorphic-flowered genera. An exception among the zygomorphic-flowered genera is Couroupita in which all species are indehiscent and there is no sign of an operculum. A few zygmorphic-flowered species have reverted back to indehiscent fruits. For example, Bertholletia excelsa has an opercular opening smaller in diameter than the seeds and an operculum that drops into the fruit when it dehisces. When ripe, the fruits of this species drop to the ground with the seeds trapped inside; thus the fruits of this species are functionally indehiscent, a feature not found in any other species of neotropical Lecythidaceae. Other species with secondary indehiscence are Lecythis rorida, a riverine species which drops its entire fruit into the water at maturity with the operculum intact (the line of opercular dehiscence is visiblea and the operculum may occasionally drop from the fruit) and Lecythis gracieana, L. lurida, L. parvifructa, and L. prancei which always drop to the ground with the operculum intact.

Related Terms

Indehiscent fruit

Dehiscent fruit

Opercular rim