Hypocotyl

Definition

The hypocotyl is the stem-like structure found between the seed leaves (cotyledons) and the root in a developing plant embryo. It plays a crucial role in early seedling growth by pushing the cotyledons above the soil surface during germination.

5 Must Know Facts For Your Next Test

1. The hypocotyl elongates during seed germination, helping to lift the cotyledons out of the soil.
2. It is located below the cotyledons and above the radicle in an embryonic plant.
3. In dicots, the hypocotyl often bends to form a hook that protects the shoot tip as it emerges from the soil.
4. The length and strength of the hypocotyl can be influenced by environmental factors such as light and gravity.
5. During germination, cell division and elongation in the hypocotyl are driven by plant hormones like auxins.

Review Questions

• What is the primary function of the hypocotyl during seed germination?
• Where is the hypocotyl located in relation to other parts of a plant embryo?
• How do environmental factors affect hypocotyl development?

Related terms

cotyledon: The first leaves that appear on a plant embryo, providing nutrients for early development.

radicle: The part of a plant embryo that develops into the primary root.

epicotyl: The region of an embryo or seedling stem above the cotyledon which eventually develops into leaves and stems.