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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