"Megaherbs" evolved to make most of sub-Antarctic sunshine: New Zealand study

New Zealand scientists said Friday they had solved the mystery of why so many plants clinging to bleak sub-Antarctic islands had large deeply-colored flowers and giant leaves.

University of Otago botany researchers said the insect-pollinated "megaherbs" on New Zealand's sub-Antarctic islands stood out from other flora, which were small, wind-pollinated plants that mainly reproduced by self-pollination or asexual reproduction.

The researchers thermally imaged six species of Campbell Island megaherbs, which had mainland relatives that were small and pale flowered, and found their flowers and leaves heated up rapidly to make the most of rare moments of sunshine and calm weather.

The leaf and flower temperatures of all six species were considerably higher than surrounding temperatures, with the greatest heating seen in Campbell Island daisies.

Study co-author Dr Janice Lord said these daisies and other megaherbs appeared 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," Lord said in a statement.

Their adaptions mirrored those of giant tropical alpine plants, she said.

"Plants in those climates face similar challenges in terms of cloudiness and the cold, especially at night," said Lord. Endit