Botany and Plant Science

Sporopollenin is a major component of the tough outer (exine) walls of spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments.

The megasporangium is surrounded by layers of sporophyte tissue called the integument. The integument and structures within i.e.,megasporangium and megaspore are called the ovule.

In this type, the ovary is monolocular. The ovules are few or reduced to one and borne at the base of the ovary. The ovule when solitary often fills the ovary cavity e.g., sunflower.

In this type, the ovule takes a 90 degree turn so that the micropyle is at right angles to the funicle.

Ovaries are attached directly to the receptacle, but can be sunken into it superior with no stalk, or on stalk-like extensions of the receptacle, as in Isomeris arborea. The ovary surrounds one or more locules in which ovules develop from placenta.

The Rosaceae or rose family is a large family of flowering plants, Roses can be herbs, shrubs or trees. Most species are deciduous, but some are evergreen.They have a worldwide range, are the most diverse in the northern hemisphere. The flowers have superior ovaries.

If a gynoecium has multiple carpels fused into a single structure, it is syncarpous. A syncarpous gynoecium can sometimes appear very much like a monocarpous gynoecium.

It is the outermost whorl consisting of units called sepals.These are typically green and enclose the rest of the flower in the bud stage, however, they can be absent or prominent and petal-like in some species.

It is stalk or the basel barren part of a flower. A flower with pedicel is called pedicellate, e.g., Hibiscus, Caesalpinia and without pedicel is called sessile, e.g., Polianthes, disc floret of Helianthus.

It is the second whorl internal; to die calyx. It is made up of petals which are usually enlarged, delicate, bright coloured and often with sweet fragrance. Their function is to attract insects for pollination and also to protect the inner essential whorls.

The flowers are not scented as birds have good vision but poor sense of smell.

Pollen grains are light, dry and non-sticky.  In some plants the pollen grains are even winged, so that they are easily carried by the wind.

Some plants never open their flowers to ensure complete self-pollination. This condition is called Cleistogamy, e.g., Commelina bengalensis, Oxalis, Viola, etc., The cleistogamous flowers are bisexual small, inconspicuous, colourless and do not secrete nectar.

Anthers and stigma of the bisexual flowers of some plants mature before the opening of the buds to ensure self-pollination, (e.g.,) Wheat, Rice, Pea, etc..

The plants have well developed conducting tissues, the xylem has xylem vessels and the phloem has sieve tubes and companion cells. The xylem and phloem are arranged in the form of vascular bundles.