to Richea scoparia
Life is tough on top of Hobart’s Mount Wellington. Temperatures frequently drop below zero, bitter-cold winds blow year round, and snow can fall any time. It’s no wonder that one little resident plant known as the “Honey Bush” (Richea scoparia) carries its delicate reproductive organs inside secure capsules formed by fused petals (calyptra).
While that’s great for protection against the elements, it has a couple of critical drawbacks: insects can’t get in to pollinate the plant, and seeds can’t get out. However, research by Mats Olsson, now at Sweden’s University of Gothenburg, and colleagues, has revealed how R. scoparia ingeniously overcomes this problem with the aid of a small reptile, the Snow Skink (Niveoscincus micro-lepidotus ).Photo: © Martin Bicevskis
Snow Skinks occur in large numbers on Mt Wellington where, for most of the year, they scavenge mainly insects. In summer however, they feed almost exclusively on R. scoparia nectar, which they obtain by ripping open the calyptra along the plant’s flower spikes. In so doing, the skinks expose the plants reproductive organs to pollinating insects and provide an escape route for the seeds that later develop.
The researchers found that, by varying the amount
of nectar offered, R. scoparia has quite a degree of control
over its relationship with Snow Skinks. To optimise pollination in a place
with such severe and unpredictable weather, it’s best for mature calyptra
to be opened when conditions are mildest. That is exactly when lizards
and insects, being “cold-blooded” ectotherms, are out and about. And, not
surprisingly, lizards overwhelmingly prefer mature calyptra (brown and
laden with nectar) to those that are unripe (pinkish red in colour and
offering much less of a reward.)
(Article reproduced with permission from Nature Australia Magazine Volume 27 Number 3, Summer 2001-2002)
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