Lichen anatomy and physiology the Ascomycota, with about 40% of species forming such an association. Some of these lichenized fungi occur in orders with nonlichenized fungi that live as saprotrophs or plant parasites (for example, the Leotiales, Dothideales, and Pezizales). Other lichen fungi occur in only five orders in which all members are engaged in this habit (Orders Graphidales, Gyalectales, Peltigerales, Pertusariales, and Teloschistales). Lichenized and nonlichenized fungi can even be found in the same genus or species. Overall, about 98% of lichens have an ascomycetous mycobiont. Next to the Ascomycota, the largest number of lichenized fungi occur in the unassigned fungi imperfecti. Comparatively
Chlorophyll tetrapyrroles known as nonfluorescent chlorophyll catabolites (NCC's) with the general structure: These compounds have also been identified in several ripening fruits. Measurement of the absorption of light is complicated by the solvent used to extract the chlorophyll from plant material, which affects the values obtained, By measuring the absorption of light in the red and far red regions, it is possible to estimate the concentration of chlorophyll within a leaf. Ratio fluorescence emission can be used to measure chlorophyll content. By exciting chlorophyll "a" fluorescence at a lower wavelength, the ratio of chlorophyll fluorescence emission at and can provide a