04-16-2007, 09:48 PM
Can you help identify what the scales are on the following pics. This is an applw tree and the tree is covered by these scales and the crown is fading. I have taken photos with 4 different backgrounds to help see what I'm talkin about.
04-17-2007, 05:37 PM
They are :
Lichens --are symbiotic organisms made up by the association of microscopic green algae or cyanobacteria and filamentous fungi. Lichens take the external shape of the fungal partner and hence are named based on the fungus. The fungus most commonly forms the majority of the lichen's bulk, though in filamentous and gelatinous lichens this may not always be the case. The lichen fungus is typically a member of the Ascomycota—rarely a member of the Basidiomycota. ...
Wherever stable and reasonably well lit surfaces occur in nature, so will lichens. A bizarre partnership of fungus and algae, lichens will grow on soil, rock, and even trees. Although they give the appearance of being parasitic on their vegetative hosts, lichens are anything but, being self-reliant in feeding themselves through photosynthesis in their algal cells. The algae, in turn, benefits from the ability of the fungus to better find, soak up, and retain water and nutrients.
Preferring a somewhat drier habitat, lichens often occupy niches where nothing else will grow, and appear throughout the park landscape. For wildlife such as deer, squirrels, mice, and bats, these plants have become important in providing food and shelter. Additionally, lichens can be used in dating rock surfaces, and secondary compounds produced by the organisms are used in medicines, natural dyes, and perfumes. Several studies have shown the sensitivity of lichens to environmental pollution, and they have become excellent instruments for assessing levels of air toxins, thus providing a value tool for park staff to monitor the park’s habitat quality.
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