1. the parts of plant embryos or seedlings located between the cotyledons and the root
Usage: botanical term; plural of hypocotyl

Examples

• The hypocotyls of bean seedlings elongate rapidly during germination.
• Scientists measured the length of hypocotyls in different light conditions.
• The hypocotyls help lift the cotyledons above the soil surface.
• Damage to the hypocotyls can prevent proper seedling development.
• The researcher studied how temperature affects hypocotyl growth.
• In some plants, the hypocotyls remain short and thick.