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Sexual Reproduction In Flowering Plants

Question
CBSEENBI12001275

With a  neat labelled diagram, describe the parts of a typical angiosperm ovule.

Solution
Structure of ovule. Each ovule consists of nucellus surrounded by two integuments and a stalk or funiculus.

(i) Funiculus is stalk-like structure by which ovule is attached to the placenta.

(ii) Hilum. It is the point of attachment of the body of the ovule with the funiculus.

(iii) Raphe. It is the longitudinal ridge formed by lengthwise fusion of funiculus with the body of ovule in a typical anatropous ovule.

(iv) Nucellus. It is a mass of diploid cell called megas-porangium. It provides nourishment in the development of embryo sac.

(v) Embryo sac. It is the female gametophyte which contains the egg apparatus, antipodal and polar nuclei.

(vi) Integuments form seed coats i.e. testa and tegmen.

(vii) Micropyle. It is small opening which is left by the integument in the ovule for the passage of pollen tube into the ovule.

(viii) Chalaza. The basal region of ovule from where the integuments arise is called chalaza.

(vii) Micropyle. It is small opening which is left by the integument in the ovule for the passage of pollen tube into the ovule.

(viii) Chalaza. The basal region of ovule from where the integuments arise is called chalaza.

 V.S. of mature ovule to show various parts.