Xylem and phloem
| English | Chinese | Pinyin |
|---|---|---|
| xylem | 木质部 | mù zhì bù |
| phloem | 韧皮部 | rèn pí bù |
| lignin | 木质素 | mù zhì sù |
| translocation | 转运 | zhuǎn yùn |
A plant's plumbing
- A tall tree must move water up from its roots and sugars down from its leaves — without a heart.
- It uses two transport tissues: xylem 木质部 and phloem 韧皮部.
Xylem and phloem route
Watch water and sugar move through different plant transport tissues.
Xylem transports:
Xylem carries water and minerals upward.
Xylem vessels are strengthened with:
Lignin strengthens xylem and helps support the plant.
Xylem
- Xylem carries water and minerals from the roots up to the leaves.
- It is made of dead, hollow tubes strengthened with lignin 木质素 — which also support the plant.
Xylem carries water up in dead lignified tubes; phloem carries sucrose in living cells
Phloem transports:
Phloem carries sugars (translocation).
The transport of sugars in the phloem is called ______.
Translocation moves food around the plant.
Phloem
- Phloem carries sugars (food) made in the leaves to the rest of the plant.
- It moves substances both up and down — this is translocation 转运.
A stem in cross-section: the red-stained xylem sits in vascular bundles near the edge
Phloem can transport substances both up and down the plant.
Translocation moves sugars to wherever they are needed.
Xylem vs phloem
- Xylem: dead cells, one way (up), carries water + minerals.
- Phloem: living cells, both ways, carries sugars.
Xylem goes one way; phloem goes both ways. Water only travels up the xylem (root to leaf). Sugars in the phloem travel to wherever they're needed — up to growing shoots or down to the roots.
You've got it
- xylem carries water + minerals up (dead, lignified tubes that also support)
- phloem carries sugars both ways — translocation
- xylem = one-way, dead; phloem = two-way, living