Tapetum (botany)

The tapetum's unusually large nuclear constitution helps it provide nutrients and regulatory molecules to the forming pollen grains.

The following processes are responsible for this: Tapetum helps in pollen wall formation, transportation of nutrients to the inner side of the anther, and synthesis of callase enzyme to separate microspore tetrads.

Two main tapetum types are recognised, secretory (glandular) and periplasmodial (amoeboid).

In contrast, the tapetal cell walls dissolve in the periplasmodial type, and their protoplasts fuse to form a multinucleate periplasmodium.

A third, less common type, the invasive non-syncytial tapetum, has been described in Canna, where the tapetal cell walls break down to invade the anther locule but do not fuse to form a periplasmodium.