New Zealand Journal of Botany abstracts
Plastic heteroblasty in beach groundsel (Senecio lautus)
K. C. Burns
School of Biological Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand
kevin.burns@vuw.ac.nz
Abstract Senecio lautus (Asteraceae) is a
heteroblastic herb that produces entire juvenile leaves and lobed adult
leaves. Juveniles commonly grow from rock fissures where they are
shaded and sheltered from high winds, whereas adult plants are exposed
to high light and wind as they outgrow these refuges. Because the
duration each plant is sheltered varies with the depth of rock
fissures, I hypothesised that heteroblasty in S. lautus varies
plastically in response to environmental conditions. I tested this
hypothesis in a glasshouse experiment, which exposed developing plants
to different light and wind conditions. Plants grown in windy
conditions showed similar ontogenetic changes in leaf morphology to
plants growing in a control treatment. However, the juvenile-adult
transition was slowed in shaded conditions, indicating that
heteroblasty in S. lautus varies plastically in response to
light. Results were therefore consistent with the hypothesis that
plastic heteroblasty is favoured in species that experience
unpredictable environmental gradients during ontogeny.
Keywords experiment; leaf shape; morphology;
ontogeny; leaf mass per unit area
B05019; Received 11 May 2005; accepted 28 June 2005; Online
publication date 21 July 2005
New Zealand Journal of Botany, 2005, Vol. 43: 665–672
0028–825X/05/4303–0665 © The Royal Society of New Zealand 2005
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