Mammoth Memory

Plant stems

The phloem is always on the outside and the xylem is always on the inside.

To remember which is on the inside and which is on the outside remember X-rays.

Xylem are the tubes on the inside and phloem are the outside when a stem is cut

X-rays always see inside. The xylem which starts with an X for X-ray sits on the inside of the plant.

Cross section of a stem showing the xylem and phloem tubes, showing the directing of flow

This can always be double checked because xylophones (xylem is pronounced zeye-lem) are usually made of wood. The wood is on the inside of the tree so the bark of a tree, which is on the outside must be the phloem.

Xylem is the wood, the inner bark is the phloem and outer bark is dead phloem

The old dead phloem cells become the bark.

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