biology

Leonotis leonurus

Leonotis leonurus 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 Leonotis leonurus rather than just read about it. In short: Leonotis leonurus, also known as wild dagga and lion's ear, is a plant species in the mint family Lamiaceae. It is a broadleaf evergreen shrub, native to South Africa, where it is very common, with a wide altitudinal range from 5 m up to 1980 m.

Key takeaways

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

Reference excerpt

Leonotis leonurus, also known as wild dagga and lion's ear, is a plant species in the mint family Lamiaceae. It is a broadleaf evergreen shrub, native to South Africa, where it is very common, with a wide altitudinal range from 5 m up to 1980 m. It is known to have medicinal and sedating properties. The main psychoactive component of Leonotis leonurus is hypothesized to be either leonurine or a mixture of labdane-type compounds; Leonotis leonurus has been confirmed to contain leonurine according to peer reviewed journal published phytochemical analysis. Like other plants in the mint family, it also contains marrubiin. The word "dagga" comes from Afrikaans, and derives in turn from the Khoikhoi "dachab". The word "dagga" has been extended to include the genus Cannabis in Afrikaans and South African English, so the use of "wild" serves to distinguish Leonotis from Cannabis.

Description The shrub grows 2 to 3 metres (7 to 10 ft) tall (rarely to 4 m (13 ft)), and 1.5 m (5 ft) wide, with softly woody stems. The leaves are medium-dark green, 5–10 centimetres (2–4 in) long, and aromatic when crushed. The plant has hairy tubular 4–5 cm orange flowers, 3–11 together in tiered whorls (verticillasters) typical of the mint family, that encircle the square stems. They rise up to 0.9 m (2 ft 11 in) above the foliage, with flowering in summer (November to January) in some areas, but autumn to winter (April to June) in other areas.

Variation in flower colour A white-flowered variety Leonotis leonurus var. albiflora was described by George Bentham, but is not now accepted as distinct at varietal rank; yellow cultivars also exist.

Ecology The native habitat of Leonotis leonurus is among rocks and in grasslands of southern Africa, particularly in wetter eastern and southern areas. It attracts nectivorous birds (mainly sunbirds), as well as various insects such as bees and butterflies. The flowers' mainly orange to orange-red colour and tubular shape are indicative of its co-evolution with African sunbirds, which have curved bills suited to feeding from tubular flowers. The butterfly Cacyreus lingeus (Lycenidae) uses the foliage as a larval food plant.

Cultivation Leonotis leonurus is cultivated as an ornamental plant for its copious orange blossom spikes, and is used as specimen shrub or a screen in gardens and parks. It is moderately drought tolerant, and a nectar source for birds and butterflies in landscape settings. It was introduced to Europe in the 1600s. Lion's ear can be found introduced as an ornamental plant in other subtropical and Mediterranean climate regions beyond South Africa, such as California, Hawaii, and Australia where it has naturalised in some areas. In cooler climates it is used as an annual and winter conservatory plant.

Pharmacology and toxicology Marrubiin has both antioxidant and cardioprotective properties and has shown to significantly improve myocardial function. Docosatetraenoylethanolamide (DEA) is a cannabinoid that acts on the cannabinoid (CB1) receptor which has been found in the whole flower extract of the putative variety Leonotis leonurus var. albiflora. Leonotis leonurus contains several labdane diterpene–based compounds such as Hispanolone, Leonurun, Leonurine and Leoleorins. C-N Leonurine (also known as SCM-198 in research) is a pseudoalkaloid that has been isolated from Leonotis leonurus, Leonotis nepetifolia, Leonurus japonicus, Leonurus cardiaca (motherwort), Leonurus sibiricus, as well as other plants of family Lamiaceae. Leonurine is easily extracted into water. One experimental animal study suggests that the aqueous leaf extract of Leonotis leonurus possesses antinociceptive, antiinflammatory, and hypoglycemic properties. An animal study in rats indicated that in high doses, lion's ear has significant toxicological adverse effects on organs, red blood cells, white blood cells, and other important bodily functions. Acute toxicity tests in animals caused death for those receiving a 3200 mg/kg dose. A 1600 mg/kg dose of whole plant extract led to changes in red blood cells, haemoglobin concentration, mean corpuscular volume, platelets, and white blood cells.

Traditional uses Infusions made from flowers, seeds, leaves, or stems are widely used to treat tuberculosis, jaundice, muscle cramps, high blood pressure, diabetes, viral hepatitis, dysentery, and diarrhoea. The leaves, roots, and bark are used as an emetic for snakebites, and bee and scorpion stings. The fresh stem juice is used as an infusion drink for "blood impurity" in some parts of South Africa.

Legal status

Latvia Leonotis leonurus has been illegal in Latvia since November 2009, and is classified as a Schedule 1 drug. Possession of quantities up to 1 gram are fined up to 280 euros. Possession and distribution of larger quantities can be punished with up to 15 years in prison.

Poland Leonotis leonurus was banned in Poland in March 2009. Possession and distribution lead to criminal charges.

See also Leonurine Leonurus cardiaca Leonurus japonicus Leonotis nepetifolia Leonurus sibiricus

References

External links

Missouri Botanical Garden - Kemper Garden Center: Leonotis leonurus Archived 2010-10-18 at the Wayback Machine United States Department of Agriculture profile of Leonotis leonurus (lion's ear)

See also List of Lamiaceae of South Africa

Illustrations

Worked examples

Example 1 — a first encounter with Leonotis leonurus

Start with the simplest possible case. Write down what Leonotis leonurus 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 Leonotis leonurus 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 Leonotis leonurus 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 Leonotis leonurus

In research: Leonotis leonurus 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 Leonotis leonurus 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: Leonotis leonurus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Butterfly food plants, Drought-tolerant plants, Endemic flora of South Africa, so understanding it makes those chapters shorter.
In everyday life: Look for Leonotis leonurus 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 Leonotis leonurus in 20 minutes

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

Frequently asked questions

What is Leonotis leonurus in simple terms?

Why does Leonotis leonurus 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 Leonotis leonurus?

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 Leonotis leonurus.