Definition of hypocotyl in US English:

hypocotyl

noun

Botany
  • The part of the stem of an embryo plant beneath the stalks of the seed leaves or cotyledons and directly above the root.

    • ‘During weeks 5 and 6 there was further development of the hypocotyl root axis and cotyledons.’
    • ‘Callus was formed on cotyledons, hypocotyls, and radicles of embryos.’
    • ‘A wide variety of organs from various plant species were analysed: roots, stems, hypocotyls, leaves, fruits, and petioles.’
    • ‘Shoots comprising the two cotyledons and the hypocotyl were separated from the roots.’
    • ‘In wild-type Arabidopsis plants, the roots, hypocotyls, and inflorescence stems exhibit gravitropic bending.’

Pronunciation

hypocotyl

/ˈhīpəˌkätl/