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Cycads in bloom
All cycads are diecious, meaning that there are both male and female plants. You
can tell by the symbols on the labels what gender each plant is. Male plants have
cylindrical cones, the underside of which have a multitude of anthers. The cones
of female plants are more rounded, and carry the ovules.
The cycads are one of the oldest groups of plants to rely on animals for pollination.
This duty is usually carried out by weevils, which transport the pollen from the male
cycad to the female. For a long time, scientists assumed that these earliest pollination
relationships were fairly casual and non-specific, but more recent research has revealed
that even some of the most archaic cycads have developed quite intricate mechanisms
to ensure pollination.
The cones of the male cycad emit a scent that attracts weevils, which find protection
and food between its scales. The cones also provide a place for the weevils to lay their
eggs. As they develop, the weevil larvae feed on the starchy tissue inside the cone.
Female cycad cones actually emit the same scent as male plants. Unlike them, however,
they provide neither food nor a place to lay eggs, as the tissue of their cones
contains toxins absent in the male. Disappointed, the weevils fly on to the next
plant – after fulfilling their purpose as pollen transporters.
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Cycads in bloom (MP3, 621 KB)
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