Foliose lichens

Lichens Crustose lichens, foliose lichens, fruticose lichen... 

Pseudocyphelarins. P. A C2iH220g, Mr 402.40, prisms, mp. 173-175 C. A depside from the foliose lichen Pseudocyphellaria vaccina, occurring together with P. B (C2 H240g, Mr 404.42). 

C21H20O7, Mr 384.39, orange-red cryst., mp. 201 °C. An anthraquinone from the foliose lichen Solorina crocea, the undersides of the thalli are colored orange. S. is used as a reference substance for HPLC analysis of lichen substances. 

Dena ina (Alaska, USA) sheh tsadn nde A large foliose lichen is used for coughs, tuberculosis, and general sickness. Boil and drink decoction. Also used for bleeding that won t stop (Garibaldi 1999)... 

Certainly the growth form of lichen thalli cannot be considered as a principal characteristic on which taxonomy can be based. The foliose lichens, for example, do not form a taxonomic group of related species but only a morphological unity. The lichens of one family, even of one genus, may belong to the crustose, foliose, and fruticose growth form. 

Intermediate Forms between Crustose and Foliose Lichens... 

The thallus of foliose lichens is formed by flattened lobes, which are heteromerous and dorsoventral in structure. Two principal types, the laci-niate and the umbilicate growth form, can be distinguished. Laciniate thalli adhere more or less firmly to the support on which they grow. Either the whole lower surface is in contact with the substrate or the margin of the lobes becomes free and bends upwards. The thalli are usually attached by rhizines or rhizoidal hyphae. The umbilicate lichens are platelike and attached by a central discoid holdfast called the umbilicus (Fig. 47). 

The thalli of foliose lichens of the laciniate type, for example, those of Cetraria (Fig. 73), are sometimes nearly erect so that they are often considered to be fruticose. The lobes are fastened by the lower surface and in older thalli the base begins to rot. This further proves the arbitrariness of classification based on thallus types. 

In our experiments (Blum, 1964), the time required for saturation for most of the investigated fruticose and foliose lichens was 2-4 minutes, for gelatinous lichens Collema cristatum and C flaccidum) about 6 minutes, and for Dermatocarpon vellereum and D, miniatum about 9 minutes. The crustose, wandering, desert lichens Aspicilia esculenta and A, fruticulosa achieved saturation in 17 and 26 minutes, respectively. 

The results of our experiments have shown that the relationship of water content in the thallus when the lichen is in a saturated atmosphere (in equilibrium with vapor pressure) to the water content in a thallus saturated by liquid water differs greatly in lichens. The lowest values were shown by Collema flaccidum (14%), C. cristatum (20%), Aspicilia esculenta (22%), and A. fmticulosa (23%). The highest values were held by Cetraria islandica (64%) and Dermatocarpon miniatum (68%). For most fruticose and foliose lichens the relation between the water content in the thallus in equilibrium with vapor pressure of the saturated atmosphere and the maximum saturation with liquid water was within 40-50%. 

There seems no reason to doubt that the decomposition of crustose and foliose lichens invading bare rock surfaces contributes small amounts of humus to the surface, and that the lichens themselves trap more, permitting the establishment of other humus-requiring species of plants. It is equally clear, however, that except in certain areas and on certain rock types, chemical breakdown of minerals by lichens is extremely slow and, relative to the humus-forming role, almost insignificant. There is also abundant evidence that, except on the smoothest of rock surfaces, lichens are often not pioneers, but actually follow the establishment of other pioneer plant types, especially bryophytes. 

Another method of direct measurement can be used for certain fruticose lichens that are not attached to the substratum. Karenlampi (1971), for example, placed loose colonies of various reindeer mosses (Cladonia) in boxes on the forest floor. Every 1-4 weeks these were removed from the boxes, air-dried, weighed, and returned to the boxes without damage. A rather similar technique was tried by Miller (1966) for foliose lichens but with less success because of breaking up of the thalli. 

Phillips, H. C. (1969). Annual growth rates of three species of foliose lichens determined photographically. Bull. Torrey Bot. Club 96, 202-206. 

Following this concept we can see that, unless there is a marked difference in size, it is virtually impossible for any foliose lichen to colonize the surface of another foliose lichen without the eventual destruction, through lack of light, of the species serving as the substrate. Equally, it is impossible for an autotrophic lichen to colonize the ventral surface of either an autotroph or a heterotroph because insufficient light is available for growth. But it is perfectly possible for any heterotrophic species to colonize the ventral surface of an autotroph, i.e., the ventral surface of any foliose lichen is freely open to colonization by heterotrophic species. Here, of course, the limitations on colonization lie in the normally low availability of organic carbon supply. 

Taylor, C. J. (1967). The Lichens of Ohio. Part I. Foliose Lichens. Ohio State University, Columbus, Ohio. 

From stereocaulon vesuviamm, a foliose lichen, abundantly growing over volcanic rocks [3055],... 

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