Growing Food: A Guide to Food Production

• Hypogeal germination, where the cotyledon(s) remain below the soil surface,
  within the testa and only the apex and first leaves are raised upwards.
  Examples: horse (broad) bean, peas, maize and most monocotyledons.


• Epigeal germination, where the cotyledon(s) and shoot apex are lifted above the
  soil surface; they turn green and become the first leaves of the new plant.
  Examples: castor beans, haricot beans and most dicotyledons.
  With onions, a sharply bent, tubular cotyledon breaks the soil surface and slowly
  straightens. The cotyledon base encloses the shoot apex, and the first leaf emerges
  through a small opening at the base of the cotyledon.

Figure 9. Hypogeal germination in Maize

Figure 10. Epigeal germination in Haricot Bean

Some plants such as the runner bean (Phaseolus multiflorus) and peas (Pisum sativum)
are normally hypogeous ie they display hypogeal germination, although their cotyledons
arise out of the ground and display epigeal germination.

48 TONY WINCH