Botany and Plant Science

Albizia belongs to family fabaceae. In Albizzia, vegetative propagation take place with the help of nonfleshy roots. The non fleshy roots develop adventitious buds which grow to form new plants. 

Stomata are not completely absent in all hydrophytes (e.g., floating plants have them on the upper surface). Bundle sheaths are characteristic of C4 plants, not all hydrophytes.

A pollen grain is the male gametophyte in seed plants. At the time of release, it is considered an immature male gametophyte.

Nucellus, embryo sac, and micropyle are all parts of the ovule. A pollen grain is a separate structure (the male gametophyte) that is not part of the ovule itself.

Asphodelus is known to have a tritegmic ovule, meaning it has three integuments. Most angiosperms are bitegmic or unitegmic.

The most common type of ovule in angiosperms is the anatropous ovule, not the orthotropous one.

During double fertilization, the pollen tube typically grows into the embryo sac and discharges its male gametes and contents into one of the two synergid cells.

After arriving at the wall of the ovary, the pollen tube enters the ovule either through the micropyle or by some other route. The entrance of the pollen tube through the micropyle is the normal condition and is known as porogamy. In some cases the pollen tube enters the ovule through the chalaza(chalazogamy e.g., Casuarina), or through integuments (mesogamy e.g. Cucurbita).

In the given figure A-central cell, B-egg nucleus, C-plasma membrane, D-synergid, E-filiform apparatus, F-male gametes, G-vegetative nucleus.

The body of the ovule consists of a mass of parenchymatous cells named nucellus. It is equivalent to megasporangium $(2n)$. Megaspore mother cell or megasporocyte is a diploid$(2n)$ cell which undergoes meiosis to form a linear tetrad of four haploid megaspores (n). Normally, the chalazal megaspore is the functional megaspore while the other three degenerate.

In many aquatic plants with emergent flowers, pollination occurs by wind or insects, e.g., lotus, water lily, water hyacinth.

One Microspore mother cell after meiosis produce 4 pollen grains.

The microspore or pollen grain is the first cell of male gametophyte. The microspore starts dividing and it is known as precocious. 

In tenuinucellate ovules, the nucellus is thin and often disappears. The endothelium (a specialized layer of the inner integument) then provides nourishment to the developing embryo sac.

Statement A is correct because heartwood is central, dark, and durable. Statement B is correct because tyloses are balloon-like ingrowths of xylem parenchyma into vessel lumens. Statement C is incorrect because latewood (autumn wood) is formed during the autumn or winter season, not the spring season (which produces earlywood).