Crustose lichens

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

Fig. 15.3. Crustose lichen Lecidea lactea growing on dunite, a rock composed of the silicate olivine ((Mg, Fe)2Si04). Note dark stain (arrowed) below lichen representing amorphous silica coated in iron produced by lichen weathering (Purvis, 2000).

Picrolicbenic Acid. 6-Hydroxy-2 -methoxy-2,4 dioxo-4,6 -dlpentylspi rofben zofuran-3 2H),T -[2,5jcyclo-hexadieneJ-5-carboxylic acid picrolichenin. C H O, md wt 442.49. C 67.85%, H 6.83%, O 25.31%. Bitter acidic principle of crustose lichen, Pertusaria amara (Ach.) Nyl., Pertusariaceae. Isoln Alms, Ann. Pharm. 1, 61 (1832). 

In their review of lichens in metal-enriched environments, Purvis and Halls (1996) present a list of lichens reported as rust-stained on iron-rich rocks, and an additional list of lichens typical of rocks rich in iron sulfide. Iron and steel serve sometimes as substrates for lichens (e.g. Brightman and Seaward, 1977 Garty, 1993). Crustose lichens are often observed to grow on old cannons (Figs. 6 and 7). The cannons located along the shore in Normandy, France were put in their present position less than 60 years ago (Fig. 7). Measurements of the lichen surface on these substrate may provide information on the rate of growth of certain crustose species. 

Figure 6. Crustose lichens on a cannon, Lacko, Sweden, September, 1992.

Figure 8. Epilithic crustose lichens on a stone wall (right side of the picture) in Florence, Italy, August, 1987. Fe ions prevent the growth of lichens and other lithobionts on the left side of the wall.

Figure 13. Toxic effect of Zn-ions (arrows) on epilithic crustose lichens and mosses. The Zn ions derive from galvanized plates and objects fixed to the roof. Laerdalsoyri, Norway. Summer, 1992.

Lichens may grow on Pb/Zn-rich rocks and associated soils. Purvis and Halls (1996) present a list of 61 terricolous lichen species characteristic of Pb/Zn-rich environments in Britain and Europe. Epilithic crustose lichens were observed also on heaps of mine spoil containing Ee and Pb near old silver mines in Sala, Sweden (Fig. 9). 

Fig. 5. Cutout of a photographed sample of the crustose lichen (Aspicilia caesiocinerea) from the southern part of the Black Forest with conformation observed in the crystalline state and Fischer projection of (+)-aspicillin (100)...

Phorophyte specificity and environmental parameters versus stochasticity as determinants for species composition of corticolous crustose lichen communities in the Atlantic rain forest of northeastern Brazil. Mycological Progress G, 117-136. 

Chipewyan (Alberta, Canada) White crustose lichens on aspen baik, along with the dead tree periderm, are scraped off and put on cuts and deep wounds to stop bleeding (Maries et al. 2000)... 

Seri (Sonora, Mexico) hast yamdsa ( rock lichen ) Gray foliose and orange crustose lichens on rocks are taken as a tea to induce vomiting (Felger and Moser 1985)... 

White cmstose lichen Witoto/Boia (Loreto, Peru) An unidentified white crustose lichen growing on Rinorea racemosa is sometimes used (along with other botanicals and ash) to add to the resin of Virola sebifera or V. elongata to make oo -koey, a hallucinogenic orally ingested paste (Mckenna et al. 1984 UBC 2014)... 

Crustose lichens never possess a lower cortex. They are attached to soil, rock, or tree bark by the hyphae of the medulla and the contact is so intimate that they are practically inseparable from the substrate. A patch of crusta-ceous lichen may belong to one species and yet be composed of many individuals which have fused together. Simple crustose lichens are homoio-merous. They lack a cortex and are therefore granular in structure. The mycelium spreads over the substrate in a thin filamentous mat enclosing the algae. 

In some crustose lichens elongated, small lobes replace the areoles. These lobes can be fastened to the substrate by the entire lower surface or the margin of the thallus can be free and ascending. Different combinations of these characteristics lead to a variety of described growth types. 

Linnaeus (1762) discussed the ability of crustose lichens to colonize unweathered rocks and to accumulate windblown material. According to Linnaeus Crustaceous lichens are the first foundation of vegetation. ... 

Many crustose lichen species that grow on limestone, particularly the obligate calcicoles, have thalli which are partly or wholly embedded in the substratum (Fry, 1922). Rhizines, originating from the medulla, may penetrate down to 15 mm in the limestone (Smith, 1921). The high solubility of calcium carbonate, compared to that of the minerals of other rocks, facilitates this deep penetration (Fry, 1922 Syers, 1964). Dissolving the underlying limestone in dilute hydrochloric acid revealed a network of fine... 

A metal-complexing action may be involved in the accumulation by lichens of radioactive cations such as "Sr. Subbotina and Timofeev-Resovkii (1961) reported high accumulation coefficient values for crustose lichens suspended in aqueous solutions of the radioactive isotopes of several metals. Schulert (1962) suggested that a chelation mechanism was involved in the accumulation of Sr by lichens and Tuominen (1967) showed that the uptake of Sr by Cladonia alpestris was a physicochemical process and was not metabolically controlled. 

It is dangerous to extrapolate experimental findings obtained in the laboratory to the conditions which exist in the field. As pointed out by Smith (1962), no evidence has yet been presented to show that lichen compounds form soluble complexes in the field. Lichen compounds are extracellular and are usually present in the medulla (Smith, 1921), which in crustose lichens is in direct contact with the substratum and may act as a primitive water reservoir (Smith, 1961). Depsides and depsidones, similar to the compounds used by Schatz (1963), Syers (1969), and Iskandar and Syers (1971, 1972), are the most abundant lichen compounds (Smith, 1962). Thus in crustose lichens, a reserve of slightly soluble lichen compounds that may form soluble complexes with cations is in direct contact, orincloseproximity, to the rock substratum. 

More recently, enormous thickenings of cortices or epinecral layers of placodial and crustose lichens were reported from northeast Afghanistan (Poelt and Wirth, 1968), from the Atacama (Follmann, 1965b), and from the Negev in Israel (Galun, 1963), where almost 60% of the heteromerous lichens have a more or less voluminous, amorphous upper layer. Until we can obtain experimental data from these desert lichens, the question of whether illumination is the primary cause of cortex thickening will remain unanswered. The thickening may also be a response to wind erosion. 

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