Pandanus

Key takeaways

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

Reference excerpt

Pandanus is a genus of monocots with about 578 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. Common names include pandan, screw palm and screw pine. The genus is classified in the order Pandanales, family Pandanaceae, and is the largest in the family.

Description

The species vary in size from small shrubs less than 1 metre (3+1⁄2 feet) tall, to medium-sized trees 20 m (66 ft) tall, typically with a broad canopy, heavy fruit, and moderate growth rate. The trunk is stout, wide-branching, and ringed with many leaf scars. Mature plants can have branches. Depending on the species, the trunk can be smooth, rough, or warty. The roots form a pyramidal tract to hold the trunk. They commonly have many thick stilt roots near the base, which provide support as the tree grows top-heavy with leaves, fruit, and branches. These roots are adventitious and often branched. The top of the plant has one or more crowns of strap-shaped leaves that may be spiny, varying between species from 30 centimetres (12 inches) to 2 m (6+1⁄2 ft) or longer, and from 1.5 cm (5⁄8 in) up to 10 cm (4 in) broad. They are dioecious, with male and female flowers produced on different plants. The flowers of the male tree are 2–3 cm (3⁄4–1+1⁄4 in) long and fragrant, surrounded by narrow, white bracts. The female tree produces flowers with round fruits that are also bract-surrounded. The individual fruit is a drupe, and these merge to varying degrees forming multiple fruit, a globule structure, 10–20 cm (4–8 in) in diameter and have many prism-like sections, resembling the fruit of the pineapple. Typically, the fruit changes from green to bright orange or red as it matures. The fruits can stay on the tree for more than 12 months.

Evolution The oldest credible fossil of the genus is Pandanus estellae, which is known from a silicified fruit found in Queensland, Australia, dating to the Oligocene epoch around 32–28 million years ago. Phylogenetic analyses of the maternal DNA of Pandanus has shown the genus to be divided into two large groups (Clade I and Clade II), with each of those groups further subdivided into two smaller groups (Subclade Ia, Subclade Ib, Subclade IIa, and Subclade IIb). The split between Clades I and II was determined to have occurred during the early Miocene, whereas the splits between Subclade Ia and Ib and between Subclade IIa and IIb were determined to have occurred during the Middle Miocene Climatic Optimum. Nuclear target-capture genomics revealed that the evolutionary trajectory of the genus was heavily shaped by reticulate evolution and transoceanic adaptive introgression across the Indian Ocean. Nuclear data identified a key lineage, designated Clade Ba (which contains the widely-dispersed species Pandanus tectorius, among others), which has acted as a genetic and biogeographical "bridge" connecting Asian and Afro-Malagasy populations through bidirectional gene flow. Additionally, while geographically isolated "swamp" lineages across the Palaeotropics possess very similar morphological traits, nuclear analysis demonstrated that they do not share a hybrid origin; their shared characteristics are instead a product of convergent evolution driven by similar climatic pressures.

Taxonomy Though often called "pandanus palms", these plants are not closely related to palm trees. The genus is named after the Malay word pandan given to Pandanus amaryllifolius, the genus's most commonly known species. The name is derived from Proto-Austronesian *paŋudaN (which became Proto-Malayo-Polynesian *paŋdan and Proto-Oceanic *padran). It has many cognates in Austronesian languages, underscoring its importance in Austronesian cultures, including Atayal pangran; Kavalan pangzan; Thao panadan; Tagalog pandan; Chamorro pahong; Manggarai pandang; Malagasy fandrana, Tongan fā; Tahitian fara; Hawaiian hala all referring to plants of similar characteristics and/or uses whether in the same genus (particularly Pandanus tectorius) or otherwise (in the case of Māori whara or hara; e.g. harakeke). Pandanus is traditionally divided into six subgenera (Coronata, Kurzia, Lophostigma, Pandanus, Rykia, and Vinsonia); however, molecular phylogenetic analyses have shown these subgenera to not represent the true evolutionary history of Pandanus as all but Coronata are either polyphyletic or paraphyletic.

Selected species

Note: several species previously placed in Pandanus subgenera Acrostigma and Martellidendron are now in the distinct genera Benstonea and Martellidendron, respectively.

Distribution and habitat Pandanus is a Paleotropical genus. The greatest number of species are found in Madagascar and Malaysia.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Pandanus

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

In research: Pandanus 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 Pandanus 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: Pandanus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Maldivian cuisine, Medicinal plants, Nauruan cuisine, so understanding it makes those chapters shorter.
In everyday life: Look for Pandanus 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 Pandanus in 20 minutes

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

Frequently asked questions

What is Pandanus in simple terms?

Pandanus is a genus of monocots with about 578 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics.

Why does Pandanus 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 Pandanus?

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 Pandanus.