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Unformatted text preview: owth. Putative active growth mechanisms of burial response: A – removal of light source on
buried leaves, or photosynthetic stem, results in stem elongation response for non-lignified stem. B – removal of
light stimuli on stem or stem apice, results in gravitropic stimuli and subsequent vertical growth. C – removal of light
stimuli on one side of ~1cm thick photosynthetic stem on steep dunes results in positive influence on growth of
shaded side, but not exposed side, and thus active curvature of stem to normal growth relative to the dune surface
(this could equally apply to covered and exposed leaves). Putative growth mechanisms whereby stems are
oriented close to normal, but not through an active process of burial response: D – phototropism to dominant light
source under unburied conditions, for instance the 33o S latitude sun for the Eastern Cape Province, which
corresponds well to 30o dune surfaces on north facing slipfaces. E – sand avalanches limited to dune slipfaces
acting on stem and leaf area, and causing downward moveme...
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This document was uploaded on 01/17/2014.
- Winter '08