Welwitschia mirabilis: Formation and Distribution of Chlorophylls

Abstract

Summary Chlorophyll formation was studied in seedlings of Welwitschia mirabilis . No chlorophyll was detectable in dark-germinated seedlings but the presence of protochlorophyll could be derived from in vivo spectra. Upon transfer into light chlorophyll formation commenced after a short lag period. The mode of light-dependent chlorophyll formation is typical of that in the Angiospermae and not of that in the Gymnospermae which form chlorophyll in the dark. Two chlorophylls could be extracted and identified as normal chlorophyll a and b. The ratio of chlorophyll a/b was higher in the cotyledons and leaves of young seedlings than in those of older plants. Low-temperature spectra indicated different in vivo forms of chlorophyll a. Their ratios change with age. No significant differences in the in vivo spectra of chlorophylls between Welwitschia and other plants could be detected and on this basis no taxonomic inferences could be drawn.