Q.The phenomenon observed in some plants wherein parts of the sexual apparatus is used for forming embryos without fertilisation is called:

When an embryo forms without fertilisation but still uses components of the sexual apparatus (the flower's reproductive structures), we're looking at a special reproductive strategy. The key distinction here is that the process bypasses fertilisation yet involves the ovule and related sexual structures to produce seeds.

Apomixis is precisely this phenomenon. In apomictic plants, seeds develop without the fusion of gametes—no fertilisation occurs—but the embryo arises from cells within the ovule (like the nucellus or an unfertilised egg cell). The sexual apparatus is present and functional in structure, yet reproduction proceeds asexually. Citrus and mango are common examples where nucellar cells give rise to embryos directly. …

The question asks us to identify a rather unusual reproductive strategy that sits somewhere between sexual and asexual reproduction. The key phrase here is "parts of the sexual apparatus" being used to form embryos "without fertilisation." This tells us we're dealing with structures normally involved in sexual reproduction—ovules, nucellus, integuments—but the process bypasses the fundamental step of gamete fusion.

Let's work through what each option actually means.

Parthenocarpy refers to fruit development without fertilisation. The ovary swells and matures into a fruit, but no seeds form (or seeds form without viable embryos). Bananas, seedless grapes, and certain varieties of pineapple are classic examples. The sexual apparatus isn't forming embryos here; it's simply that the fruit develops in the absence of the usual fertilisation trigger. This doesn't fit our requirement.

Vegetative propagation involves structures like runners, rhizomes, tubers, or bulbs—parts of the plant body that have nothing to do with flowers or the sexual apparatus. A potato tuber or a ginger rhizome produces a new plant, but these are vegetative organs, not ovules or any component of the flower's reproductive system.

Sexual reproduction obviously requires fertilisation—the fusion of male and female gametes—so it's immediately ruled out by the phrase "without fertilisation."

That leaves us with apomixis, and this is where things get interesting. In apomixis, seeds are produced, and those seeds contain embryos, but fertilisation never occurs. The embryo develops from a cell in the nucellus (nucellar embryony) or from an unfertilised egg cell or another cell of the gametophyte. The critical point is that the structures involved—the ovule, the embryo sac, sometimes even the egg apparatus—are all parts of the sexual apparatus. The plant is using its sexual machinery, but short-circuiting the sexual process itself. …