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Subantarctic plants use colour to tap sun

NZ NewswireNZ Newswire 16/09/2016

Some plants on New Zealand's bleak subantarctic islands are brightly coloured so they can "heat up" to make the most of fine weather.

University of Otago researchers investigated why "megaherbs" stand out with large deeply coloured flowers and giant leaves compared with other plants on the island and similar plants on the mainland.

Department of Botany researchers thermally imaged six species of Campbell Island megaherbs and compared them with mainland relatives that are small and pale-flowered.

Leaf and flower temperatures of all six species were considerably higher than simultaneously measured surrounding temperatures.

It suggested the plants made the most of rare moments of sunshine and calm weather.

Campbell Island daisies heated up the most.

Co-author Dr Janice Lord says the plants appear to have evolved deeply pigmented flowers and often large, thick, hairy leaves to cope with some of the most relentlessly cloudy and cool conditions in the world.

"Their dark floral pigments are able to more efficiently harvest the unpredictable, intermittent sunshine to speed up metabolism and attract insects seeking warmth, and their large rosette leaves can provide mini-glasshouse effects," Dr Lord said.

The findings appear in the journal Polar Research.

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