Nectar Production in Abutilon II. Submicroscopic Structure of the Nectary

Abstract

The nectary hair cells of Abutilon are particularly rich in mitochondria and endoplasmic reticulum. The vacuoles are initially small but enlarge and coalesce during nectar production when invaginations of the plasmalemma are often present at the tips and at the cross-walls of the hairs. The presence of these invaginations suggests that nectar may be transported through the nectary by a process resembling pinocytosis and exocytosis. Entry of nectar into the hair is restricted to a route through the protoplast of the stalk cell by a cutinized sheath in the outer walls of this cell