# Plant Vascular Bundle Transport

> A stem cross-section shows the plant's plumbing. Xylem carries water and minerals upward, phloem carries sugars to where they are needed, and the cambium between them makes new cells.

Web page: https://cellnaut.com/topics/plant-vascular-bundle-transport

![Teaching illustration: Plant Vascular Bundle Transport](https://cellnaut.com/texture-references/gpt-image-2-biology-more-teaching-2026-05-31/jpg/plant-vascular-bundle-transport-teaching.jpg)

## Labelled parts

1. **Epidermis**: The outer protective layer of the stem.
2. **Cortex**: Ground tissue that stores food and gives support.
3. **Ring of vascular bundles**: In many dicot stems the bundles are arranged in a ring.
4. **Pith**: Central storage tissue.
5. **Xylem vessel**: Hollow, lignified tubes that carry water and minerals upward.
6. **Water transport**: Water moves up, pulled by evaporation from the leaves.
7. **Cambium**: A thin layer of dividing cells that adds new xylem and phloem.
8. **Phloem sieve tube**: Living tubes with perforated end walls that carry sugars.
9. **Companion cell**: Supports a sieve tube cell, supplying energy and proteins.
10. **Organic solute transport**: Sugar flows from sources such as leaves to sinks such as roots and fruit.

## Key points

- Xylem vessels are dead, hollow tubes; water is pulled up by evaporation from the leaves.
- Phloem sieve tubes are living cells helped by companion cells, and carry sugar from sources to sinks.
- The cambium divides to add xylem and phloem, thickening the stem.

## Check yourself

**1. Which tissue carries water upward?**

- A. Xylem
- B. Phloem
- C. Cambium
- D. Epidermis

**Answer:** A. Xylem - Xylem vessels carry water and minerals from the roots.

**2. What do companion cells do?**

- A. Carry water up the stem
- B. Support the sieve tube cells
- C. Make new bark
- D. Absorb light

**Answer:** B. Support the sieve tube cells - Sieve tube cells have lost much of their contents and rely on their companions.

## Related lessons

- [Specialized Cells and Tissues](https://cellnaut.com/learn/specialized-cells-and-tissues)

## See it in 3D

- [Guard Cell](https://cellnaut.com/studio/guard)
- [Root Hair Cell](https://cellnaut.com/studio/rootHair)
- [Plant Cell](https://cellnaut.com/studio/plant)