BIOLOGY LECTURE ON SEEDS

It develops from ovule inside ovary [female reproductive part of flower]after fertilisation with pollen.

SEED has four parts 

1 OUTER SEED COAT

2 COTYLEDONS

3 PLUMULE

4 RADICLE

                                           DICOT

 Means if two cotyledons are present.Two chambers which stores food .They have seed coat Ex PEA ,GRAM.[ALL PULSES]

 Embryo is embedded inside endosperm has two thin cotyledons joined to an axis called TIGELLUM It shows RADICLE & PLUMULE hidden between cotyledons.Ex GRAM PEA.

HILUM Point of attachment of seed with stalk.

   MONOCOT

 Means if one cotyledon stores food as in RICE, WHEAT ,MAIZE.

Monocot have no seed coat.


Single cotyledon,endospermic,NO SEED COAT.Outer covering is membranous fused with fruit wall.ENDOSPERM is separated from embryo by ALEURONE LAYER.Embryo is small in a groove at one end.It consists of one cotyledon called SCUTELLUM,a short axis with plumule & radicle

Seed may be endospermic or non endospermic.

ENDOSPERM

 It is fleshy food storage tissue rich in oil.

SEED COAT

 Protects the inner parts is tough, outer ,hard blackish shell also called TESTA  inner membrane is called TEGMEN.Ex GRAM[CHANA]

CARUNCLE 

In PEA There is an outgrowth at micropyle It is spongy absorbs moisture during seed germination.

PERISPERM 

Thin white papery membrane surrounds endosperm in CHICK PEA[CHANA] Below perisperm there is endosperm food storage tissue rich in oil.

PLUMULE give rise to shoot.It is covered by sheath called COLEOPTILE.

RADICLE give rise to root.It is protected by COLEORHIZA

Some monocots are nonendospermic like ORCHIDS.