Fluorescence Emission Spectra of Desiccation-tolerant Cryptogamic Plants During a Rehydration — desiccation Cycle

UV-A induced fluorescence emission spectra of three desiccation-tolerant cryptogamic plant species were measured in the dry states, during rehydration and a subsequent dehydration period of 4 h. These cryptogamic species showed the blue-green fluorescence and the red chlorophyll fluorescence as had been described for higher plants. Moss leaves (Tortula ruralis), lacking an epidermis, exhibited only a weak bluegreen fluorescence, whereas the thallus of the lichens Cladonia convoluta and Cladonia furcata showed a stronger blue-green fluorescence. The chlorophyll fluorescence ratio red/far-red (F690/F735) decreased when drying out, whereas the blue-green fluorescence and the fluorescence ratios blue/red (F440/F690) and blue/far-red (F440/F735) increased by an order of magnitude. It is assumed that these changes are not caused by a new formation and breakdown of blue-green fluorescing plant phenolics, but by altered optical properties of the leaves and thalli during desiccation.