biology

Parmelia saxatilis

Parmelia saxatilis is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Parmelia saxatilis rather than just read about it. In short: Parmelia saxatilis, commonly known as the salted shield lichen or crottle, is a species of foliose lichen in the family Parmeliaceae. Several morphologically similar species, formerly lumped together, are now distinguished by their DNA.

Key takeaways

Parmelia saxatilis belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Parmelia saxatilis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Parmelia saxatilis from memory before moving on to harder problems.

Reference excerpt

Parmelia saxatilis, commonly known as the salted shield lichen or crottle, is a species of foliose lichen in the family Parmeliaceae. Several morphologically similar species, formerly lumped together, are now distinguished by their DNA.

Taxonomy It was first described in 1753 by Carl Linnaeus with the name Lichen saxatilis. Erik Acharius transferred it to Parmelia in 1803. Molecular phylogenetic studies have shown that Parmelia saxatilis is a member of a species complex–a group of morphologically similar but genetically distinct species. P. discordans, P. ernstiae, P. hygrophila, P. imbricaria, P. mayi, P. omphalodes, P. pinnatifida, P. serrana, P. submontana, P. sulymae, and P. rojoi are other members of this complex. In the case of the European members of this complex, there is no reliable set of morphological and chemical characteristics that can be used to distinguish between these species, and therefore DNA analysis is the only reliable way to identify them. This has been demonstrated in studies conducted in Scotland and Italy.

Description The lichen has a greenish-gray to bluish-gray thallus that can turn brown in exposed locations. It typically grows on rock, although it is sometimes found on bark or wood. Parmelia saxatilis is used to make dyes with deep red-brown and rusty-orange colors. Known as "crotal" in Scotland, it was used to dye traditional cloths including Harris tweed. A somewhat similar species complex with a cosmopolitan distribution is the Parmelia sulcata group, generally growing on trees.

Conservation In 2021, Parmelia saxatilis was assessed for the global IUCN Red List. Because the lichen is common, abundant, and widely distributed with a stable population size, it is considered of least concern.

Ecology Parmelia saxatilis is a known host to the lichenicolous fungus Abrothallus parmeliarum.

See also List of lichens named by Carl Linnaeus

References

Illustrations

Worked examples

Example 1 — a first encounter with Parmelia saxatilis

Start with the simplest possible case. Write down what Parmelia saxatilis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parmelia saxatilis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parmelia saxatilis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parmelia saxatilis

In research: Parmelia saxatilis appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Parmelia saxatilis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Parmelia saxatilis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fungal taxa named by Carl Linnaeus, IUCN Red List least concern species, Lichen species, so understanding it makes those chapters shorter.
In everyday life: Look for Parmelia saxatilis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Parmelia saxatilis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Parmelia saxatilis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Parmelia saxatilis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parmelia saxatilis in simple terms?

Why does Parmelia saxatilis matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parmelia saxatilis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parmelia saxatilis.