germination
ScientificCloser Look
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.
Example Sentences
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By contrast, the encased spores showed ~1,000x greater UV tolerance and remained capable of germination even after enduring −196°C for more than a week or 55°C for an entire month.
From Science Daily
The adult plants are known to rely on a certain type of fungi that develop structures within the plant's roots, but whether these same fungi also help with germination has not been established.
From Science Daily
Its seeds can lay dormant for years until intense heat and other cues from a wildfire triggers germination.
From Los Angeles Times
"They wanted to play and build stuff. They were making houses or ships or scenery, and they wanted to jump in, and all of that learning was the germination of Roblox," he says.
From BBC
The seeds of some chaparral plants need to be treated with heat or liquid smoke to simulate the fire conditions that would naturally trigger germination.
From Los Angeles Times
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