Glossary Details – Lecythidaceae

Glossary Details:

Title: Placentation of L. poiteaui. Photo by C. M. Potascheff.

Description: Placentation of L. poiteaui as shown in cross-section based on Mori & Bolten 8636 from Suriname. The ovary is 4-locular, each of which is made up of a single carpel as indicated by the white dots. Each septal unit includes a head (outlined in light blue) and a base (outlined in green) and consists of tissue from adjacent carpels. The placental tissue originates from apices of a single carpel. There are 4 septal units and 4 placentae in a 4-locular ovary, 6 in a 6-locular ovary, etc. The placental units are derived from the opposite ends of a carpel.

Term:

Septal unit

Definition:

The shape of a section of a septum, including both the septal unit stalk and the septal unit head, as viewed in a cross section through the placenta.

Notes:

The septal unit consists of tissue from adjacent carpels and includes the septal unit base and an expanded portion that develops into one-half of the placenta in one locule and the other half in the adjacent locule. There are 4 septal units in a 4-locular ovary, 6 in a 6-locular ovary, etc. The placental unit consists of one-half of the head of a septal unit.