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Pre-built, then inflated

How Does Bamboo Grow So Fast?

Bamboo does not build itself as it grows. The whole stem is made in advance, folded up, and then pumped full of water.

A fast tree in a yearPerhaps a metreBamboo in a dayUp to about ametre — in oneday
A year of tree growth, in a day.

  1. Step 1 of 5

    Bamboo is a grass, not a tree.

    A tree One growing point pershoot, at the tipBamboo A growing zone at thebase of every segment

    That matters, because a grass grows from the base of each segment rather than the tip. A bamboo stem has dozens of growing zones at once.

  2. Step 2 of 5

    The whole stem is built underground before it appears.

    1 The shootformsunderground2 Every segmentalready there,squashed short3 It comes upcomplete

    A new shoot comes up already containing every segment it will ever have, squashed up short. It never adds a segment after that.

  3. Step 3 of 5

    Growing is then mostly a matter of filling with water.

    Water pushed intothe cells Every segmentstretches at onceDozens of segments lengthen at once — not one tip.

    Each segment's cells stretch as water pushes into them. Building is slow; stretching something already built is very fast.

  4. Step 4 of 5

    And it is not paying for the growth itself.

    The old canes abovestill feedingall seasonThe rhizome networkbelowyears of storedsugarThe new shootspends, andpays nothingback
    A shoot can put on most of a metre in a day while making no food of its own

    The shoot is fed by an existing underground network of stems belonging to older canes. It arrives with a bank account already full.

  5. Step 5 of 5

    The joints are what stop a hollow cane folding.

    Hollow all the waythroughA solid wall at everyjointSo a kink has nowhereto start
    A drinking straw with bulkheads. That is the whole engineering trick.

    A hollow tube is stiff for its weight, the way a bone is, but it kinks if you bend it far. Bamboo puts a solid wall across the stem at every joint, so a kink has nowhere to start.

    Many bamboos flower once, all together across a whole region, and then die — sometimes after a hundred years of never flowering at all.

The short version

Bamboo grows a metre a day because the whole stem is pre-built underground and then simply stretched with water, funded by the older canes.

Try it yourself

Compare a bamboo cane with a wooden stick of the same weight. The hollow tube resists bending far better, which is why scaffolding is made of it.

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