biology

Medicago

Medicago 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 Medicago rather than just read about it. In short: Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species.

Key takeaways

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

Reference excerpt

Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species. The genus name is based on the Latin name for that plant, medica, from Greek: μηδική (πόα) Median (grass). The genus is distributed mainly around the Mediterranean Basin, also extending across temperate Eurasia and sub-Saharan Africa. Its best-known member is alfalfa (M. sativa), an important forage crop.

Description Most members of the genus are low, creeping herbs, resembling clover, but with burs (hence the common name). However, alfalfa grows to a height of 1 metre (3+1⁄2 ft), and tree medick (M. arborea) is a shrub. Members of the genus are known to produce bioactive compounds such as medicarpin (a flavonoid) and medicagenic acid (a triterpenoid saponin). Chromosome numbers in Medicago range from 2n = 14 to 48.

Taxonomy The species Medicago truncatula is a model legume due to its relatively small stature, small genome (450–500 Mbp), short generation time (about 3 months), and ability to reproduce both by outcrossing and selfing. Comprehensive descriptions of the genus are Lesinš and Lesinš 1979 and Small and Jomphe 1989. Major collections are SARDI (Australia), USDA-GRIN (United States), ICARDA (Syria), and INRA (France).

Species The genus contains at least 87 species. Recent molecular phylogenic analyses of Medicago indicate that the sections and subsections defined by Small & Jomphe, as outlined below, are generally polyphyletic. However, with minor revisions sections and subsections could be rendered monophyletic.

Evolution Medicago diverged from Glycine (soybean) about 53–55 million years ago (in the early Eocene), from Lotus (deervetch) 49–51 million years ago (also in the Eocene), and from Trigonella 10–22 million years ago (in the Miocene).

Etymology The genus name is based on the Latin name for alfalfa, medica, from Greek: μηδική (πόα) Median (grass).

Distribution and habitat The genus is distributed mainly around the Mediterranean Basin, also extending across temperate Eurasia and sub-Saharan Africa.

Ecology

Symbiosis with nitrogen-fixing rhizobia Béna et al. (2005) constructed a molecular phylogeny of 23 Sinorhizobium strains and tested the symbiotic ability of six strains with 35 Medicago species. Comparison of these phylogenies indicates many transitions in the compatibility of the association over evolutionary time. Furthermore, they propose that the geographical distribution of strains limits the distribution of particular Medicago species.

Insect herbivores Medicago species are used as food plants by the larvae of some Lepidoptera species including the common swift, flame, latticed heath, lime-speck pug, nutmeg, setaceous Hebrew character, and turnip moths and case-bearers of the genus Coleophora, including C. frischella (recorded on M. sativa) and C. fuscociliella (feeds exclusively on Medicago spp.).

Agricultural uses Agronomic research has been conducted on Medicago species. Other than its best-known member, alfalfa, several of the prostrate members of the family (such as M. lupulina and M. truncatula) have been used as forage crops. Select species in the Medicago genus naturally develop spiney pods during the reproductive phase of growth (such as M. intertexta and M. polymorpha). Despite having high levels of agronomic performance, these are typically viewed as undesirable in sheep based farming systems due to their ability to become lodged in wool, reducing fleece value. Breeding efforts in the 1990s have yielded spineless varieties of burr medic, providing valuable production amongst farming systems in low rainfall (<300mm annual), free draining, alkaline soils.

Notes

References

External links Media related to Medicago at Wikimedia Commons Data related to Medicago at Wikispecies

Illustrations

Worked examples

Example 1 — a first encounter with Medicago

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

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

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

Frequently asked questions

What is Medicago in simple terms?

Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species.

Why does Medicago 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 Medicago?

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 Medicago.