Give the characteristics of anemophilous flowers.

The flowers that are pollinated by the agency of wind are called wind-pollinated or anemophilous flowers. These flowers have certain characteristic features that help their pollination by wind. These are as follows: Anemophilous flowers are small They do not have attractive colours and do not emit fragrance. Anthers are versatile. These flowers produce a large number of pollens to ensure pollination so that if the pollens are wasted the pollination is not affected. Stigma is very elaborate, and it is mostly bifid and feathery. Pollen grains are dry, light weight so that can be easily carried by wind.

Describe the structure of ovule in plants.

The ovule is a small structure attached to the placenta by means of a stalk called a funicle. The body of the ovule fuses with a funicle in the region called the hilum. Thus, the hilum represents the junction between the ovule and the funicle. Each ovule has one or two protective envelopes called integuments. These are the protective layers. Inside the integuments is the multicellular structure nucellus which envelops the embryo sac. The latter is an eight nucleated seven celled structure that contains the synergid cells, antipodals, egg cells and a central cell. The diagram of ovule has been given below:

Explain the embryonic development in angiosperm plants. Draw a labelled diagram of the heart-shaped embryo.

The development of an embryo in angiosperms involves the following steps: The embryo develops from the diploid zygote. The diploid zygote divides and redivides by mitosis to form a group of diploid cells called embryos. Initially, the zygote undergoes a transverse division to form a two-celled proembryo consisting of an upper central terminal cell and a lower basal cell. The central terminal cell lies towards the micropylar end, while the basal cell lies towards the centre. The basal cell undergoes repeated divisions to form a multicellular structure called suspensor. The suspensor pushes the embryo towards the endosperm and thereby provides nourishment to the developing embryo. The upper terminal cell divides repeatedly to form the embryo proper. The fully developed embryo consists of the radicle, plumule and one or two cotyledons. The embryo having two cotyledons is called a dicot embryo. The embryo with only cotyledon (scutellum) is called a monocot embryo. In monocot embryos, the radicle is covered by a protective covering called as coleorhiza and the plumule is covered by coleoptile. Figure: Embryonic development of angiosperms