1. Many trichomes on plant
surfaces are secretory. This panel shows nectary trichomes in Abutilon megapotamicum.
The flower is at the left. The five nectaries lie at the inner faces of the
fused sepals, where the dotted line is. Each nectary is a cluster of several
thousand haira with globular heads, through which a sugary nectar is secreted
in pressure-driven pulses. The central image shows hairs just before secretion
starts in a flower that is about to open; on the right are hairs with drops
of nectar on the head cells and in larger aggregates in the background. Pre-nectar
passes up the hairs, probably through plasmodesmata, and emerges at the apices.
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