The embryo develops from the zygote at the micropylar end of the embryo sac. It is formed as a result of syngamy when a male gamete fuses with the egg cell. The embryo is present in the seed and is made up of the embryonal axis, cotyledons (one or two). Radicle and plumule are present at the two ends of the embryonal axis.
The
zygote produced after fertilization must undergo various cellular divisions and
differentiations to become a mature embryo.
Dicot
Embryo
A
dicot embryo contains two cotyledons and an embryonal axis. Epicotyl is the
portion above the cotyledons in the embryonal axis and terminates in the stem
tip known as plumule. Hypocotyl is the lower end of the embryonal axis
terminating in the root tip or radicle. The root cap covers the radicle.
Monocot
Embryo
The
monocot embryo possesses only one cotyledon. In grasses, the cotyledon is known
as scutellum and present on the lateral side of the embryonal axis. Epicotyl
has a shoot apex enclosed in coleoptile and the root cap is enclosed in an
undifferentiated sheath known as coleorhiza.
The
mature embryo of dicotyledons is globular and heart-shaped. It consists of two
cotyledons. Monocotyledons possess only one cotyledon.
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