Pufal, Gesine , Garnock-Jones, Philip .
Crossing the border – rain operated capsule-opening from African and American desert species and plants from alpine New Zealand.
Hygrochastic capsules open when wet and close when dry, the reverse of xerochasy. For a long time hygrochasy was considered rather uncommon and restricted to plants in arid environments (especially Aizoaceae) where it most likely serves as protection against seed predators and seasonally unfavourable germination conditions. It also aids in detection of sufficient rainfall for germination.
In the last few years this specific plant response to rain has been found to occur in rain forests, temperate forests, wetlands, and other temperate regions and it is present in a wide range of different families and genera. However, despite a number of reports and investigations on the dispersal of those species, the mechanism itself has not been investigated in detail.
Here we show that hygrochasy occurs in several unrelated cushion plants in alpine regions in New Zealand, which was previously unknown. Cell wall structure, cell arrangement, capsule anatomy, and biomechanics of New Zealand alpine Veronica (Plantaginaceae), introduced species of Veronica, and alpine Colobanthus species (Caryophyllaceae) have been analysed using different sectioning and staining techniques. We relate capsule functioning to growth form, plant life history and environmental factors.
Finally, we compare hygrochastic capsules in alpine and deserts plants with respect to their opening mechanism and rate, dispersal and distribution. We conclude that hyrochasy is not a specific mechanism restricted to only a few species and linked to certain areas but is rather a plant response found in various species and habitats.
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1 - Victoria University of Wellington, School of Biological Sciences, Kelburn Parade, New Kirk Building, PO Box 600, Wellington, 6140, New Zealand
alpine New Zealand
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 4:30 PM