science

Pandanales

Pandanales is a science 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 Pandanales rather than just read about it. In short: Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where they are in a sister group relationship with the Dioscoreales.

Key takeaways

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

Reference excerpt

Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where they are in a sister group relationship with the Dioscoreales. Historically the order has consisted of a number of different families in different systems but modern classification of the order is based primarily on molecular phylogenetics despite diverse morphology which previously placed many of the families in other groupings based on apparent similarity. Members of the order have a subtropical distribution and includes trees, shrubs, and vines as well as herbaceous plants. The order consists of 5 families, 36 genera and about 1,610 species.

Description

Pandanales are highly diverse including large arboraceous plants of tropical rainforests and coastal areas, climbing vines and lianas, as well as very small achlorophyllous (mycoheterotrophic) and saprophytic herbaceous forest floor species. This has made it difficult to reliably define synapomorphies, but the loss of trimery distinguishes many of them from other lilioid monocots. The Pandanales order is distinctive with its highly variable and hardly definable floral morphology, especially the number of stamens and their structure as well as many other characteristics. In some of the members, different interpretations exist regarding the composition and organization of the reproductive structures. The order includes plants with traits that seem atypical when compared to other groups of monocots. A good example is the female reproductive organ and its position relative to other parts of the flower. Some of the species included in the families Pandanaceae and Stemonaceae show flowers formed from only one carpel, while in the Triuridaceae, a family that lacks chlorophyll, the carpels are free from each other. In fact, the Triuridaceae possess the least "typical" flower morphology in the order.

Taxonomy

History The components of the order sensu APG have been difficult to place consistently, and historically have been associated with a number of other groupings. The Bentham & Hooker system (1883) had a similar order under the name Nudifloreae, incorporating:

Pandaneae Cyclanthaceae Typhaceae Aroideae Lemnaceae The Wettstein system (1935) placed the order in class Monocotyledones and used a different circumscription, incorporating:

Pandanaceae Sparganiaceae Typhaceae The Cronquist system (1981) placed the order in subclass Arecidae in class Liliopsida [=monocotyledons] with only one family:

Pandanaceae In the classification system of Dahlgren the Pandanales were in the superorder Pandaniflorae (also called Pandananae) with the single family Pandanaceae.

Angiosperm Phylogeny Group The APG III system (2009) places the Pandanales in the monocots. Both the APG III and APG II systems include five families in this order. Since the morphology of the order varies on such scale, its classification and phylogeny are based on genetic analyses. Inside the order, some doubt remains about the position of the entirely mycoheterotrophic family Triuridaceae, since it is the only one on which genetic analyses have not yet been applied. With high probability, the family may be sister to the Velloziaceae, but similarities with the family Zingiberaceae (which is a part of a whole different order – Zingiberales) do not exclude the chance for a different phylogeny. The family Velloziaceae on its own is placed at the base of the tree. The Pandanaceae and Cyclanthaceae are sister groups, and they form a clade which on its own is sister to the Stemonaceae (a family composed of two more clades).

Evolution The order Dioscoreales holds sister relationship with Pandanales by diverging from them around 121 million years ago in the mid-Cretaceous. The formation of the crown groups took place with a difference of 2 million years between the orders - 116 Mya for the Dioscoreales and 114 Mya for the Pandanales. However, the stem group of the Pandanales is much older and goes back to 130 Mya in the early Cretaceous.

Phylogeny

Subdivision The composition of the order in APG III and APG II were slightly from that in the 1998 APG system, which used the circumscription

Cyclanthaceae Pandanaceae Stemonaceae Velloziaceae APG III includes the following families;

Cyclanthaceae Pandanaceae Stemonaceae Triuridaceae Velloziaceae

Distribution The order contains members mainly distributed in all the tropical and subtropical regions of the world, both New and Old World (including Africa, South America, Australia and Asia). Also, a species is present in China.

Ecology

The species are members of various ecological groups, including tropical shrubs, lianas and trees, xerophytic plants, mycoheterotrophs, as well as different herbaceous representatives.

Uses Several species in this order produce strap-like leaves used for basketry and mats; Pandanus (Pandanaceae) is used across Oceania for thatch, basketry, and to make cloth, and Carludovica palmata (Cyclanthaceae) leaves are made into Panama hats. Other members as Stemona are present in traditional Chinese medicine and possess medical properties. Some species are used as insecticides. Some species of Pandanus are used as ornamentals. Pandanus amaryllifolius is a common food flavoring in Southeast Asia and karuka (Pandanus julianettii) is a staple food in New Guinea.

References

Bibliography

External links Merckx V. Cretaceous Origins of Myco-Heterotrophic Lineages in Dioscoreales. 2010 Systematics and Evolution of Pandanales. Royal Botanic Gardens, Kew Angiosperm Phylogeny Web: Pandanales Berry, PE. Pandanales. Encyclopædia Britannica 2016 Data related to Pandanales at Wikispecies Media related to Pandanales at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Pandanales

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

In research: Pandanales 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 Pandanales 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: Pandanales is common in secondary-school and first-year university syllabi. It links to neighbouring topics Angiosperm orders, Extant Aptian first appearances, Pandanales, so understanding it makes those chapters shorter.
In everyday life: Look for Pandanales 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 Pandanales in 20 minutes

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

Frequently asked questions

What is Pandanales in simple terms?

Why does Pandanales 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 Pandanales?

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 Pandanales.