Orellani

Key takeaways

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

Reference excerpt

The Orellani are a group of seven related species in the genus Cortinarius that have been classified as a section of the subgenus Leprocybe or a subgenus in their own right. They are among world's most poisonous mushrooms as they contain the highly toxic compound orellanine. The best-known species are the deadly webcap (Cortinarius rubellus, formerly also known as C. speciosissimus or C. orellanoides) and the fool's webcap, C. orellanus. The mushrooms' characteristics are quite common, making them difficult to identify, which often leads to fatal poisonings. Young examples of the species often have a veil between the cap of the mushroom and the stem. This veil looks like a cobweb, hence the name. The veil however partially or completely disappears in older specimens. Some other characteristics for each of the mushrooms are given below.

Descriptions

Deadly webcap (Cortinarius rubellus) Spore color: Rusty brown to orange Cap: 3–7 cm rusty brown to orange. Often has a steeper and darker colored elevation at the top of the cap, but this varies greatly from specimen to specimen Gills: Wide gaps between the gills which can be, but are not necessarily, connected to the stem Location: Rare, but common in temperate parts of northern Europe. Has been encountered as far north as Finnish Lapland. Habitat: pine woods with acidic soil Other details: Young specimens contain a pale web between the cap and the stem. Sometimes parts of this web can be seen as a yellow ring on the stem or at the edge of the cap. The fruiting body of the mushroom blossoms from mid-summer to late autumn. Cortinarius rainierensis, described in 1950 by Alex H. Smith and Daniel Elliot Stuntz from material collected Mount Rainier National Park, is a synonym.

Fool's webcap (Cortinarius orellanus) Spore color: Rusty brown to orange Cap: 3–8.5 cm (1.2–3.3 in), concave Gills: Similar to those of the deadly webcap Location: Common throughout Europe, rare in the northern parts of Europe. Has been observed as far north as southern Norway Habitat: In forests, around trees where the soil is alkaline or acidic Other details: Young specimens of the fool's webcap also contain a web between the cap and the stem that partially or completely disappears as the specimen ages.

Toxicity

The deadly webcap and the fool's webcap both contain the toxin orellanine and orellin, orellinin and cortinarin A, B, and C. A characteristic of orellanine poisoning is the long latency; the first symptoms usually don't appear until 2–3 days after ingestion and can in some cases take as long as 3 weeks. The first symptoms of orellanine poisoning are similar to the common flu (nausea, vomiting, stomach pains, headaches, etc.). These symptoms are followed by early stages of kidney failure (immense thirst, frequent urination, pain on and around the kidneys), and eventually decreased or nonexistent urine output and other symptoms of kidney failure occur. If left untreated, death will follow. There is no known antidote against orellanine poisoning, but early hospitalization and treatment can sometimes prevent serious injuries and usually prevent death. If orellanine poisoning is suspected, emergency medical attention is advised. Both of these mushrooms can be confused with each other and many incidents of mushroom poisoning have occurred where inexperienced mushroom hunters have confused these mushrooms with edible mushrooms, such as the chanterelle, or hallucinogenic mushrooms. Extreme care should be taken when picking mushrooms like the cleaned funnel chanterelles as these mushrooms share the same habitat as the deadly webcap and the fool's webcap. The LD50 of orellanine in mice is 12-20 mg/kg body weight. From cases of orellanine-related mushroom poisoning in humans it seems that the lethal dose for humans is considerably lower. Several more mushrooms in the genus Cortinarius are suspected to contain orellanine or other deadly toxins. Among them are C. callisteus and C. limonius.

Notable poisonings In Poland in the 1950s there was a small epidemic where over 100 people became ill. What caused the illness remained a mystery until 1957 when Polish physician Stanisław Grzymala discovered that everyone suffering from the illness, which by then had claimed eleven lives, had eaten the mushroom Cortinarius orellanus. British author Nicholas Evans, his wife Charlotte Gordon Cumming, and two other relatives were accidentally poisoned in September 2008 after consuming C. rubellus and/or C. speciosissimus that they gathered on holiday. Although the poisoning was non-lethal, Evans and the others suffered severe renal damage and had to undergo kidney dialysis. All four victims were informed that they would require kidney transplants in the future. Several years later, Evans received a kidney donated by his daughter, Lauren.

Illustrations

Worked examples

Example 1 — a first encounter with Orellani

Start with the simplest possible case. Write down what Orellani claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Orellani 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 Orellani 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 Orellani

In research: Orellani appears in science 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 Orellani 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: Orellani is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cortinarius, Deadly fungi, Poisonous fungi, so understanding it makes those chapters shorter.
In everyday life: Look for Orellani 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.

How to study Orellani in 20 minutes

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

Frequently asked questions

What is Orellani in simple terms?

The Orellani are a group of seven related species in the genus Cortinarius that have been classified as a section of the subgenus Leprocybe or a subgenus in their own right. They are among world's most poisonous mushrooms as they contain the highly toxic compound orellanine.

Why does Orellani matter?

Because it connects several science 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 Orellani?

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 Orellani.