Germinate
(Seed)The beginning of growth, as of a
seed, spore, or bud. The germination of most seeds and spores occurs in response to warmth and water.
Dormant seeds are very dry and require the absorption of water to initiate the metabolic processes of respiration and begin to digest their stored food. Respiration requires the presence of oxygen, which must be sufficiently available in the
soil for germination to proceed, so the
soil must be wet but not so waterlogged as to make oxygen inaccessible. Temperatures must be above freezing (zero degrees Celsius) but not excessively hot (not more than about 45 degrees Celsius). If conditions are right, a radicle (an embryonic root) emerges from the
seed coat, anchoring the
seed; it then grows and puts out lateral
roots. In most eudicots, a part of the developing stem, either the epicotyl (the stem above the cotyledons) or the hypocotyl (the stem below the cotyledons) elongates, forming a hook and gradually pulling the
seed coat and the delicate shoot tip above the
soil surface.
Germination of eudicot seeds is normally divided into two types, designated epigeous and hypogeous. In epigeous germination, the cotyledons emerge above the
soil surface, and wither and drop off after their food stores have been used up; in hypogeous germination, the cotyledons remain below the surface and decompose after their food stores have been used up. In most monocots, food is stored in the
seed's endosperm (rather than the cotyledon), and it is the single tubular cotyledon that elongates and draws the
seed coat out of the
soil. The cotyledon conducts photosynthesis, making more food, while the shoot grows up inside the tube.
Seedling
(Germinate)A young plant grown from a
seed, rather than from a cutting, etc.
Any young plant; especially a small, young tree.