biology

Hydrocotyle

Hydrocotyle 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 Hydrocotyle rather than just read about it. In short: Hydrocotyle, also called floating pennywort, water pennywort, dollar weed, marsh penny, thick-leaved pennywort and white rot, is a genus of prostrate, perennial aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae. Description Water pennyworts, Hydrocotyles, are very common.

Key takeaways

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

Reference excerpt

Hydrocotyle, also called floating pennywort, water pennywort, dollar weed, marsh penny, thick-leaved pennywort and white rot, is a genus of prostrate, perennial aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae.

Description Water pennyworts, Hydrocotyles, are very common. They have long creeping stems that often form dense mats, often in and near ponds, lakes, rivers, and marshes, and some species in coastal areas by the sea.

Leaves Simple, with small leafy outgrowth at the base, kidney shaped to round. Leaf edges are scalloped. The leaf surfaces of Hydrocotyle are prime grounds for oviposition of many butterfly species, such as Anartia fatima. Flowers Flower clusters are simple and flat-topped or rounded. Involucral bracts at the base of each flower. Indistinct sepals.

Fruits and reproduction Elliptical to round with thin ridges and no oil tubes (vitta) which is characteristic in the fruit of umbelliferous plants. The prostrate plants reproduce by seed and by sending roots from stem nodes.

Selected species

There are over 280 species recognised in the genus Hydrocotyle that grow in tropical and temperate regions worldwide. A few species have entered the world of cultivated ornamental aquatics. A list of selected species:

Distribution Hydrocotyleae grow in wet and damp places in the tropics and the temperate zones.

Fossil record One fossil fruit of a Hydrocotyle sp. has been extracted from borehole samples of the Middle Miocene fresh water deposits in Nowy Sacz Basin, West Carpathians, Poland.

References

External links

"Hydrocotyle". Integrated Taxonomic Information System. Retrieved 25 April 2008. Lamarck, Jean Baptiste Pierre Antoine de Monet de; Poiret, Jean Louis Marie (1783–1808). "HYD". Encyclopédie méthodique: botanique /Par m. le chevalier de Lamarck. Vol. 3. QK7.L36 1783-1808.

Illustrations

Worked examples

Example 1 — a first encounter with Hydrocotyle

Start with the simplest possible case. Write down what Hydrocotyle 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 Hydrocotyle 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 Hydrocotyle 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 Hydrocotyle

In research: Hydrocotyle 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 Hydrocotyle 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: Hydrocotyle is common in secondary-school and first-year university syllabi. It links to neighbouring topics Apiales genera, Aquatic plants, Botanical taxa named by Carl Linnaeus, so understanding it makes those chapters shorter.
In everyday life: Look for Hydrocotyle 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 Hydrocotyle in 20 minutes

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

Frequently asked questions

What is Hydrocotyle in simple terms?

Why does Hydrocotyle 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 Hydrocotyle?

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 Hydrocotyle.