Vegetative propagation and seed dispersal - class-VI

There are several records of very old yet viable seeds. The oldest one is of a lupine(Lupnius arcticus) excavated from Arctic Tundra. Seeds of Lupinus arcticus, atleast $10,000$ years old were found in lemming burrows deeply buried in permanently frozen silt of Pleistocene age in ungladated central Yuzon. They readily germinated in the laboratory and have since grown into normal healthy plants.

Taraxacum (dandelion) seeds possess a pappus, which is a tuft of hairs that acts like a parachute to facilitate wind dispersal.

The pappus in Compositae is a modified calyx that forms a parachute-like structure, specifically designed to catch the wind and aid in the dispersal of seeds over distances.

Wind dispersal of seeds do not ensure a coverage of larger distance and it also depends upon the morphology of seed as well. Maple seeds are samaras that mean they have a wing like structure and is also called wind seed but is not able to cover a great distance as it does not blow with the wind but flutter on the ground.

After-ripening is a period of dormancy where seeds require time after harvest to become capable of germination. Fraxinus excelsior (European ash) is a well-documented example of seeds requiring this process.

Sporangiospores are non-motile spores produced inside the sporangia. They are generally dispersed by wind and germinate to produce new mycelium (e.g., Rhizopus, Mucor, etc.) In Chlamydomonas and Ulothrix, zoospores are formed.

In sexually reproduction organisms, the male gamete is called the antherozoid or sperm and the female gamete is known as the egg or ovum. They are not used for vegetative propagation.

Vegetative propagation is a form of asexual reproduction in plants where a new individual develops from a fragment or part of the parent plant.

Layering is a common method of vegetative propagation used for plants like jasmine, where a stem is bent to the ground to encourage root growth.

Vegetative propagation is a form of asexual reproduction of a plant. Here, only one plant is involved and the offspring is the result of one parent. The new plant is genetically identical to the parent.
Micropropagation is the practice of rapidly multiplying stock plant material to produce a large number of progeny plants, using modern tissue culture methods.
Layering is a means of plant propagation, in which a portion of an aerial stem grows roots while still attached to the parent plant and then detaches as an independent plant.
Sowing is to scatter the seeds over the land for growth
So, the correct answer is 'Sowing'

Vegetative propagation is a form of asexual reproduction of a plant. Only one plant is involved and the offspring is the result of one parent.
Almost all types of shoots and roots are capable of vegetative propagation, including, stems, basal shoots, tubers, rhizomes, stolons, corms, bulbs, and buds. In a few species, even leaves are involved in vegetative propagation. However, flowers are never involved in vegetative propagation.

If the plants lose their capacity to produce seed, the plant undergoes asexual reproduction through their vegetative parts like stem, leaf, branch, etc.

A clone is considered as the vegetatively produced descendants of a single parent because of following reason: 

Vegetative propagation is a form of asexual reproduction of a plant. Only one plant is involved and the offspring is the result of one parent. The new plant is genetically identical to the parent. The offspring of the plants are clones of the original plant since no mixing of DNA occurs. The most common forms of vegetative propagation are grafting, cutting, layering, tuber, bulb or stolon formation, suckering and tissue culture.

Asexual reproduction or vegetative reproduction is when offspring are genetically identical to the parent. The offspring of the plants are clones of the original plant since no mixing of DNA occurs. The most common forms of vegetative propagation are grafting, cutting, layering, tuber, bulb or stolon formation, suckering and tissue culture.

• In plants, receptacle or thalamus is a thick part of the stem from which the flower organs grow. Stipule is a small leafy outgrowth at the base of the leaf. The sepals of a flower that form a whorl enclosing the petals and forms a protective layer around the flowers.
• Carpels, on the other hand, is the female reproductive organ in a flower consisting an ovary, a stigma and probably a style. It produces egg cells and protects a developing baby plant.

Organisms reproduce for perpetuation of species because individuals have a limited life span. Organisms may reproduce sexually as well as asexually. The sexual reproduction involves formation of haploid gametes through the process of reduction division or meiosis. The haploid gametes fuse during fertilization to form diploid zygote. Thus, restoring the normal ploidy. The asexual reproduction does not involves gamete formation through meiosis or their fertilization. The vegetative propagation in plants is a type of asexual reproduction in which plant body is propagated directly from some vegetative part of adult plant.

Jasmine grows from their branches cut and planted by the branch touching the soil developing roots and growing into a separate plant independent of the mother plant.

• Dispersal of seed is important as if seeds germinate near to parent plants it will increase a lot of competition for air, water, and food as well. 
• If competition increases it will lead to the death of the species and dispersal also leads to exposure to a new environment that helps in adaptation and evolution.

Seeds that travel in water is modified certain mechanism that make them light and filled with air so that they are able to travel a long distance and reach to places that are far from the parents. Its best example is the modification of mesocarp of coconut that helps it in hydrochory and able it to float a long distance.

Some plants develop adventitious buds on their leaves which get detached and develop new plants. Leaves of Bryophyllum develop small plantlets with adventitious roots along their margins. These get detached and give rise to a complete plant. Thus it is a natural method of vegetative propagation in this plant with the help of leaves. Leaves of some other plants such as Kalanchoe, Begonia and Streptocarpus also develop adventitious buds in their leaves. 

Bryophyllum is a plant genus of the Crassulaceae. These plantlets arise from mitosis of meristematic-type tissue in notches in the leaves. Bryophyllum are naturalised in many parts of the tropics, and deliberately cultivated for their attractiveness or for their interesting reproduction. Reproduction in Bryophyllum occurs asexually through vegetative propagation by leaves. The leaf of Bryophyllum is broad and has notches at its margins. Buds arise from the notches. These buds are called epiphyllous buds. These buds can give rise to new plants with adventitious roots, shoots and small leaves. The new plants then detach from the leaves and develop into a mature plant after coming in contact with the soil. 

Begonia is a well-known example of a plant that reproduces vegetatively through its leaves. Potato reproduces via tubers (modified stems), onion via bulbs, and tulip via bulbs.

Plant like Bryophyllum buds grow in the margins of leaves. When a leaf of this plant falls on a moist soil, each bud can give rise to a new plant. So the correct option is 'Moisture'.

In Bryophyllum and Kalanchoe, the plants can vegetatively propagate while the leaves still are attached to the branch. The leaves of this plant begin the process of mitosis and asexually reproduce in the form of plantlets that cover the edges of each leaf. Once these plantlets develop, they drop off and grow into new plants when they find fertile ground.

Epiphyllous buds (adventitious buds) develop on the margins of leaves in plants like Bryophyllum. These buds serve as a means of vegetative reproduction, allowing the plant to grow into new individuals.

Saintpaulia also is known as African violets commonly propagated asexually. Plants can be divided into smaller daughter plants or even grown from leaf cuttings. 

Vegetative propagation is possible by leaves as the process is continued by differentiating leaf parenchyma, which is probably often phloem parenchyma or companion cells, the two of which are often indistinguishable,  into new root and shoot apical meristems.

Radical leaves are those that arise from a reduced stem, often appearing to emerge directly from the root or ground level. Cauline leaves arise from the aerial stem, while ramal leaves arise from branches.