Botany and Plant Science

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.

In some plants, when the mature pollen falls on the receptive stigma of the same flower, it fails to bring about self-pollination. It is called self-incompatibility. Under such conditions, cross-pollination is the only option.

The genus Salvia belongs to family Labiatae (Mint family) in which the gamopetalous corolla is two-lipped (Bilabiate). The lower lip provides platform for the visiting insect and the upper lip is just like a hood which protects the floral organs. The flowers are protandrous. Each flower has two epipetalous stamens located in anterio-lateral position.It is an entomophilus flower.

Fourth whorl (female organ of the flower) consists of carpel or megasporophylls. The pistil consists of Fourth whorl (female organ of the flower) consists of carpel or megasporophylls. The pistil consists of ovary, style and stigma.The ovary contains one or more round or oval ovules (rudimentary seeds). Each ovule encloses embryo sac.

Xylem tissue is composed of several types of cells, including tracheids (long, tapered cells) and vessels (shorter, wider cells arranged in columns). Both tracheids and vessels are conducting elements that transport water and minerals, so option C is correct.

Xylem vessels consist of vessel elements that are dead at maturity, forming long continuous tubes for water transport. These cells lose their protoplasm and end walls to create efficient pipelines.

Mature xylem vessels are dead cells with no living contents. They lack cytoplasm, nuclei, and all other organelles, forming empty tubes for water conduction.

Pits are thin areas in cell walls present in both xylem and phloem cells. They allow lateral transport of water and substances between adjacent cells.

Xylem vessel walls contain both cellulose for structural strength and lignin for waterproofing and rigidity. This combination creates strong, impermeable tubes for water transport under tension.

The endodermis is the single cell layer surrounding vascular tissues in roots, acting as a selective barrier. It regulates mineral uptake into the vascular cylinder via the Casparian strip.

The root cortex is the tissue region between the epidermis (outer layer) and endodermis (inner layer). It stores food and helps transport water and minerals to the vascular cylinder.