Page 7 - LN-CH-2[2]

 Embryonal axis below the cotyledon is the hypocotyl.
 The terminal part of the hypocotyl is called the radicle (root tip).
 The root tip is covered by the root cap.

Monocot embryo:

 Possesses only one cotyledon
 In grass family the cotyledon is called scutellum.
 Scutellum situated towards one side of the embryonal axis.
 Radicle and the root cap enclosed by a sheath called coleorhiza.
 The portion of the embryonal axis above level of attachment of scutellum is called epicotyls.
 Epicotyl has the shoot apex or plumule enclosed by hollow foliar structure called coleoptile.
 Seed is the final product of the sexual reproduction.
 Seed consists of seed coat, cotyledon and an embryo axis.
 Cotyledon stores the reserve food material for development and germination.
 Matured seed without endosperm called non-albuminous. (Ground nut)
 A part of the endosperm retained in matured seed is Albuminous.
 Remainants of nucellus in the matured seed is called perisperm. E.g. black peeper, beet.
 The wall of the ovary develops into the wall of fruit called pericarp.
 Fruit developed from the ovary is called true fruit.
 In apple, strawberry, cashew, the thalamus contributes in the fruit formation is called false fruit.
 Fruit developed without fertilization is called Parthenocarpic fruits.

APOMIXIS AND POLYEMBRYONY.

 Apomixis is very common in Asteraceae and grasses.
 Seeds are produced without fertilization.
 Apomixis is a type of asexual reproduction which mimics the sexual reproduction.
 Diploid egg cell is formed without meiosis and develops into seed without fertilization.
 In Citrusand Mango the nucellar cells starts dividing, protrude into the embryo sac and develop
into embryo.
 Ovule having more than one embryo is termed as polyembryony.
 Hybrid plants are developed by apomixis to maintain the genetic identity.