Anderson, O.R., Lin, G. Gregory-Wodzicki, K.M., and Griffin, K., submitted
11/98 to American Journal of Botany, Effects of elevated CO2 concentrations
on leaf fine structure, physiognomy and photosynthesis of some C-3 and C-4
plants grown in Biosphere 2
Plants grown in Biosphere 2 at elevated carbon dioxide
concentrations and those grown in nearby greenhouses at ambient (normal)
carbon dioxide concentrations were examined for differences in fine structure
and leaf morphology. Chloroplasts of C-3 plants (Carica papaya,
Clitoria racemosa, Epipremnum pinnatum, Musa acuminata,
and Piper auritum) grown in elevated atmospheric carbon dioxide in
Biosphere 2 have longer intergrana thylakoids that occupy a greater proportion
of the chloroplast volume than the same species grown in greenhouses at
ambient CO2 levels (p<<0.01). There were no differences for C-4 plants
including grasses (Pennisetum ciliare, and Pennisetum purpurea)
and Atriplex cinerea. Among the species studied for leaf morphological
analyses (Rhizophora mangle, Laguncularia racemosa, Avicennia
germinans, Simmondsia sinensis, Hyptis emoryi, Clitoria
racemosa, and Atriplex cinerea) there are no consistent differences
in leaf size, shape, or tooth frequency related to CO2 concentration; rather,
the data are more consistent with the hypothesis that phenotype and microclimate
account for more of the observed variance than carbon dioxide concentrations.