biology

Punctelia reddenda

Punctelia reddenda 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 Punctelia reddenda rather than just read about it. In short: Punctelia reddenda is a widely distributed species of foliose lichen in the family Parmeliaceae. It occurs in Africa, Europe, North America, and South America, where it grows on bark and on rock.

Key takeaways

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

Reference excerpt

Punctelia reddenda is a widely distributed species of foliose lichen in the family Parmeliaceae. It occurs in Africa, Europe, North America, and South America, where it grows on bark and on rock.

Taxonomy It was first described scientifically in 1903 by Scottish cryptogam specialist James Stirton, as Parmelia reddenda. The type was collected by botanist James McAndrew near New Galloway in Scotland. In 1982, Hildur Krog transferred the taxon to Punctelia, a newly circumscribed genus, with 22 pseudocyphella-possessing species segregated from Parmelia.

Description The lichen has an upper thallus surface that is grey, and covered with bright soredia. The lower surface of the thallus is black. The thallus diameter is typically 5.0–7.5 cm (2.0–3.0 in) broad, comprising irregularly branched and laterally overlapping lobes that are 1.0–5.5 millimetres (0.04–0.2 in) wide with rounded tips. Point-like, conspicuous (i.e., readily visible) pseudocyphellae are abundant on the surface. Also abundant are coarse, granular soredia. The medulla is white. The cortex is K+ (yellow), indicating the presence of atranorin, while the medulla is negative for all lichen spot tests. A chemical analysis of Brazilian specimens using thin layer chromatography revealed the known compounds praesorediosic acid, protopraesorediosic acid, and protolichesterinic acid as well as an unidentified fatty acid. The North American species Punctelia appalachensis is similar in appearance to P. reddenda, with a black thallus undersurface and negative medullary spot test reactions. However, it is distinguishable from P. reddenda because rather than soredia, it has abundant laminal and marginal lobulae (growths of the upper cortex or thallus margin, usually with a constricted base, that fall away as propagules).

Habitat and distribution Punctelia reddenda grows on bark, but has also been recorded growing on rock. An older (1974) source considered its European distribution to be more or less limited to coastal areas ranging from southern Sweden to Brittany. A 2008 survey of parmelioid lichens in Europe indicated its presence in Germany, Spain, France, Greece, Ireland, and Madeira, also noting that it was extinct in Sweden. In North America, its centre of distribution is the Appalachian Mountains. In the Great Smoky Mountains National Park, it is only found at elevations greater than 5,000 ft (1,500 m), in hardwood or spruce forests in the mountains. In South America, it occurs in Bolivia, Brazil, Chile, and Venezuela. It is also found in South Africa and Macaronesia.

References

Illustrations

Worked examples

Example 1 — a first encounter with Punctelia reddenda

Start with the simplest possible case. Write down what Punctelia reddenda 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 Punctelia reddenda 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 Punctelia reddenda 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 Punctelia reddenda

In research: Punctelia reddenda 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 Punctelia reddenda 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: Punctelia reddenda is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lichen species, Lichens described in 1878, Lichens of Africa, so understanding it makes those chapters shorter.
In everyday life: Look for Punctelia reddenda 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 Punctelia reddenda in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Punctelia reddenda 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 Punctelia reddenda out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Punctelia reddenda in simple terms?

Punctelia reddenda is a widely distributed species of foliose lichen in the family Parmeliaceae. It occurs in Africa, Europe, North America, and South America, where it grows on bark and on rock.

Why does Punctelia reddenda 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 Punctelia reddenda?

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 Punctelia reddenda.