hypocotyls

/HH AY0 P AH0 K OW1 T AH0 L Z/
noun
  1. 1

    In plants with seeds, that portion of the embryo or seedling between the root and cotyledons.

Source: https://en.wiktionary.org/wiki/hypocotyl, https://en.wiktionary.org/wiki/hypocotyls