from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The stem of a seedling or embryo located between the cotyledons and the first true leaves.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. In plants with seeds, that portion of the embryo or seedling above the cotyledons.
from The Century Dictionary and Cyclopedia
- n. In botany, the part of a growing embryo above the cotyledons.
Yet she insistently wanted to drop this one directly into nutrient soil, watch the epicotyl lengthen, smile proudly at the upward thrusting plumule, then fuss over stipule and first foliage.
After the cotyledons have attained full length, growth in thickness begins in the area nearest the epicotyl and proceeds toward the margins.
Later, the meristems of the epicotyl (stem or top) and root axis develop, but the whole embryo is still microscopic in size.
This is the epicotyl, and another growing tip pointed toward the lower end of the kernel; this is the hypocotyl or the part which penetrates the soil and forms roots.
Bean with one cotyledon removed, after sprouting had begun. _a_, Seed-coat; _b_, cotyledon; _c_, epicotyl; _d_, hypocotyl; _e_, endosperm.
The pea cotyledons were left down in the soil, the epicotyl alone pushing up to the surface.
The part bearing the tiny leaves was formerly, and is sometimes now, called the plumule, but is generally called the epicotyl, because it grows above or upon the cotyledons.
By the time the epicotyl, the aboveground part, shoots up, the hypocotyl has already made a good start on a stable root system.
These sprout, the hypocotyl thrusts eagerly down into the soil, the epicotyl emerges like clockwork above the soil -- and someone like me comes along and picks it like the weed it is and throws it away.
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