OVULE is an megasporangium where megaspore formation takes place it develops into seed after fertilization it is present in ovary and attached to the placenta of ovary by stalk Parts of ovule are:
1.Funiculus: stalk that attaches the ovule to the placenta of ovary.
2.Hilum :Point of attachment of ovule body with the funiculus.
3.Raphe: These are the longitudinal ridge formed by the fusion of funiculus with the body of ovule.
4.Nucellus: Mass of parenchymatous tissue encloses embryo sac and provide nourishment to it.
5. Embryo sac: It contain which has 2 polar nuclei in the center ,3 antipodal cell at its one end and on the other end it has one egg and two synergid cell.
6.Integuments : covering of ovule for its protection.
7.Micropyle: Narrow pore formed by the projection of integuments through which pollen tube enters.
8. Chalaza: Place of origin of integuments or basal swollen part of nucellus.
TYPES OF OVULE
1.ORTHOTROPOUS OVULE:
Ovule is erect ,with straight body ,Hilum chalaza and micropyle all lie in the same vertical axis.Embryo sac is straight. Ex.Polygonum
•ANATROPOUS OVULE
Ovule is completely inverted due to 180˚ curvature of the funiculus.Nucellus axis is parallel to funiculus axis,Micropyle comes near the hilum but embryo sac is straight where micropyle and chalaza are in same longitudinal axis.Ex.Helianthus
•HEMITROPOUS OVULE
Body of ovule twisted half way that is at right angle to the funicle.The micropyle and chalaza are in horizontal line and these are at 90˚ to the funicle.Embryo sac is straight horizontal.Ex. Ranunculus
•CAMPYLOTROPOUS OVULE: Body of ovule is curved in such a way that micropyle and chalaza come to lie on either side of funicle .Micropyle is toward the base of funicle which is attached near the middle of ovule body.Raphe absent embryo sac is straight.Ex Mustard
•AMPHITROPOUS OVULE
Body of ovule curved in such a way that it has horse shoe shape.Embryo sac is also horse shoe shape. Micropyle,chalaza and hilum come close to each other. Ex. Capsella
•CIRCINOTROPOUS OVULE: Ovule is straight with micropyle facing upward funicle is in coiled encircle the ovule.It is orthotropous but inverted in the course of development
Ex. Opuntia
