Megaherbs: Giant, Endemic Mystery Plants of Campbell Island

On the Subantarctic Islands of New Zealand you can find megaherbs that are huge, hairy and warmer than air. These plants were first described by Joseph Hooker and Captain Ross while the two were on their Antarctic voyage. Since then they have puzzled scientists. The mystery of how these amazing plants produce heat seems to have been solved, however.

[Image Source: Flickr]

Campbell Island is an exotic and nearly untouched island that even takes Kiwis three days to reach because they have to sail south of the mainland for 600 km. Even though it has a wet, windy and cold climate, with temperatures rarely getting above 10°C, this island has an interesting endemic habitat. Covered with colorful, colossal plants and flowers and weird creatures, the landscape is surprising and eye-pleasing.

[Image Source: Flickr]

Scientists have spent years trying to explain how Campbell Island's megaherbs seem to be warmer than the air around them. According to a report on the BBC, botanist Peter Wardle, one  species, Pleurophyllum speciosum, has leaves with hairs on the ridges that create a greenhouse effect. This can heat up the leaves to 20°C and make their surface temperature much warmer than the surrounding environment.

[Image Source: Polar Research]

Lorna Little is a botanist who studied the plants for her Ph.D. at the University of Otago in Dunedin, New Zealand. She has been looking for an explanation for the effect Wardle observed. She has now published her findings in the journal Polar Research.

"The patches of megaherbs look like gardens that someone has put lots of time into," Little told the BBC. "It's really lush and colorful, a striking contrast. For me, the megaherbs on Campbell Island are the equivalent of jungles in the sub-Antarctic. But many people don't realize that there are so many colorful plants in this region. They think it's just ice and rock."

[Image Source: Polar Research]

Little took thermal pictures of flowers to check if the megaherbs are warmer than air. The result confirmed Wardle's findings: all but one of the six megaherb flowers and leaves were between 4°C and 10°C warmer than the air temperature.

Little also observed that bigger leaves catch maximum heat and better absorb solar radiation. Moreover, corrugated hairy leaves and densely-packed, darker flowers were warmer than smooth leaves and lighter flowers.

"This is the first evidence that floral and leaf heating occurs in sub-Antarctic megaherbs, and suggests that leaf hairiness, flower color and shape could provide thermal benefits like those seen in tropical alpine megaherbs," Little says in her paper.

SEE ALSO: Two-Billion-Year-Old Water Uncovered by Researchers from the University of Toronto

Via: Polar Research, BBC