Cetraria nivalis

Bruun T (1954b) Taraxerene, a naturally occurring triterpene. Acta Chem Scand 8 1291-1292 Bruun T (1969) Triterpenoids in Cetraria nivalis (L.) Ach. 

Gaskell SJ, Eglinton G, Bruun T (1973) Hydrocarbon constituents of three species of Norwegian lichens Cetraria nivalis, C. crispa, and Siphula ceratites. Phytochemistry 12 1174-1176... 

Wilkins AL (1977) The structure of a triterpenoid ketol from Cetraria nivalis. Phytochemistry 16 608-609 Wilkins AL (1980) Nephrin structure and occurrence in Nephroma species. Phytochemistry 19 696-697 Wilkins AL, Elix JA (1990) New fernene triterpenes from the lichen Pseudocyphellaria aurata. Aust J Chem 43 623-627... 

A structurally rather bizarre lipid is the monoacetylpentol (83) isolated from Alectoria ochroleuca (305). Besides spectroscopic evidence, periodate oxidation of (83) apparently produced a mixture of 8-acetoxyoctanal (84) and 2-ethyl-2-pentylpropan-1,3-dial (85) which were isolated as the corresponding 2,4-dinitrophenylhydrazones and characterised by mass spectroscopy (305). The polyester, methyl hexa(a-hydroxyvalerate) (86) has been isolated from Cetraria nivalis and Cladonia gonecha (35). 

The plant growth hormone ethylene was detected in the lichen Ramalina duriaei by Epstein 281, 282). Ott and Zwoch 569) analyzed Cetraria islandica, Cladonia rangiferina, C. arbuscula, C. sulfurina, C. cornuta, C. pyxidata, Peltigera lactucifolia and Usnea aurantiaco-ater for ethylene and found it in amounts of 0.8-5.5 pl/g dry weight/ hour. The presence of hydrocarbons with 17-33 carbon atoms has been reported 317) in Cetraria nivalis, C. crispa and Siphula ceratites in other lichens C-27, C-29 and C-31 were the main hydrocarbons 765). The hydrocarbons of the odoriferous fraction of Evernia prunastri have been examined 357). 

In spite of many observations, there is a lack of experimental analyses on the resistance of phycobionts to strong illumination, in contrast with the studies on marine algae (Biebl, 1956). There is little evidence of the harmful effects of intensive illumination on photosynthetic activity. Cetraria islandica and C. nivalis, from alpine habitats on Mount Washington, underwent a decrease in their photosynthetic rate to 17-36% at 20° C, when they were exposed to 69.1 klux, a light intensity four times the optimum for photosynthesis of these species (Bliss and Hadley, 1964). Ramalina maciformis from the bright desert habitat, showed no drop in its photosynthetic rate at 40 klux (19°C) (Lange et ai, 1970a). 

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