Parts of a Cactus

A tall cactus and one areole close up: 8 parts to name.

Parts of a Cactus

Name Date

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1 2 3 4 5 6 7 8
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Write the name of each numbered part.Answer key

  1. Stem
  2. Ribs
  3. Branches
  4. Flower
  5. Fruit
  6. Roots
  7. Areole
  8. Spines

Drawn for this site by script, 2026-09-26. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Compare: a flowering plant

All 8 parts on the diagram

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Start here: 6 main parts 6

  1. Stem The fleshy part where most cacti store water. Without true leaves, they make their food here by photosynthesis.
  2. Ribs Folds running along the stem. They let it swell after rain and shrink in drought.
  3. Flower Cactus flowers grow from areoles and are usually tubular with many petals.
  4. Roots Most cacti have fine, shallow roots. They spread out near the surface to catch rain quickly.
  5. Areole A woolly or hairy pad unique to cacti, a very reduced branch. Spines and flowers grow from areoles.
  6. Spines Highly modified leaves that grow from an areole. They defend against animals and help cut water loss by shading the stem and slowing the air.

The whole cactus: 6 2

  1. Branches Side stems growing out from the main stem. Like the arms of a tree-like cactus.
  2. Fruit Forms after a flower is fertilized. It holds many seeds and may be fleshy or dry.

How this list was compiled: Read 2026-09-26. Wikipedia, Cactus, https://en.wikipedia.org/wiki/Cactus : the stem as the main water store and, without true leaves, the site of photosynthesis; spines as highly modified leaves that defend against herbivores and reduce water loss by slowing air and giving shade; areoles, unique to cacti, as highly reduced branches, woolly or hairy areas from which spines and flowers grow; flowers usually tubular and multipetaled; ribbed or fluted stems that expand and contract with water; tree-like cacti with a trunk topped by branches covered with spines; fruits after fertilization, fleshy or dry, with many seeds; fine shallow roots spreading near the surface, some with taproots. Licence: own work

The drawing: Drawn for this site by script, 2026-09-26. Own work, nothing traced. Licence: own work

How it works

The parts of a cactus on a tall, branching cactus, from the flower on top to the shallow roots below, with one areole and its spines drawn large beside it. Start with the 6 main parts.

Read the full guide

A stem that does it all

Most cacti have no true leaves. The stem stores water and makes food by photosynthesis, and its ribs let it swell after rain and shrink in drought. Shallow roots spread near the surface to catch rain fast.

Areoles and spines

Areoles are woolly pads found only on cacti. Spines grow from them; spines are modified leaves that fend off animals and shade the stem. Flowers grow from areoles too, and fruits follow them.

  • Spot an areole and you know it is a cactus: other spiny plants do not have them.

Questions and answers

Are cactus spines leaves?

Yes. Cactus spines are highly modified leaves. They protect the plant from animals and help cut water loss by shading the stem and slowing the air around it.

What is an areole on a cactus?

A woolly or hairy pad on the stem, found only on cacti. It is a very reduced branch, and spines and flowers grow from it.

Why do cacti have ribs?

Ribs let the stem expand to store water after rain and contract again during long droughts.

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