What are the parts of a pollen grain?
Most pollen grains consist of three distinct parts. The central cytoplasmic part is the source of nuclei responsible for fertilization. The other parts constituting the wall of the grain are an inner layer, the intine, and an outer layer, the exine. The intine consists, at least in part, of cellulose or hemicellulose.
Why are pollen grains spiny?
Entomophily type of pollination takes place through the agency of insects. The entomophilous flowers are brightly coloured and fragranted to attract the insects. Their pollen grains are sticky or spiny to easily get attached with the body of pollinators.
What are the three types of pollinations based on the source of pollen?
Depending on the source of pollen grains, pollination can be divided as follows:
- Autogamy – It is the transfer of pollen grains from anther to stigma of the same flower.
- Geitonogamy – It is the transfer of pollen grains from the anther of one flower to the stigma of another flower in the same plant.
What is pollen grain morphology?
Pollen grains and spores are often described by the shape (non-angular and angular) of their outline both in polar and equatorial views. The shape of the pollen/spores may be circular, elliptical, triangular, rectangular, quadrangular or in other geometrical shapes (Fig. 4.5).
What is pollen grains short answer?
What are Pollen Grains? Pollen grains are microscopic structures, which bear androecium – a male reproductive organ of a flower. The interior section of pollen grain contains cytoplasm along with the tube cell, which converts into a pollen tube and the generative cell releases the sperm nuclei.
What is pollen grain describe the structure of pollen grain?
The pollen grain is the male gametophyte which contains the male gametes. The pollen grain is surrounded by two layers as exine which forms the outer layer and intine which forms the inner layer. The generative cell divides to form the two male gametes. The vegetative cell is responsible for the providing nutrition.
Why are pollens sticky and spiky?
Wind-pollinated plants produce lots of lightweight, smooth pollen. However, insect-pollinated plants don’t produce as much pollen and the pollen is heavy and sticky. When an insect visits a flower for food, the pollen gets caught in hairs for easy transport to another flower.
What is insect pollination called?
entomophily
Pollinators range from physical agents, especially the wind (wind pollination is called anemophily), or biotic agents such as insects, birds, bats and other animals (pollination by insects is called entomophily, by birds ornithophily, by bats chiropterophily).
What is pollinator and Pollinizer?
A pollenizer (or polleniser), sometimes pollinizer (or polliniser, see spelling differences) is a plant that provides pollen. The word pollinator is often used when pollenizer is more precise. A pollinator is the biotic agent that moves the pollen, such as bees, moths, bats, and birds.
What do you mean by anemophily?
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes.
What is NPC system?
NPC is an artificial system of classification of pollen and spore based on the three features of aperture only, i.e. number, position and character. Erdtman and Straka (1961) proposed NPC classification and palynologists all over the world accepted it.
What is the function of pollen grain?
Pollen is essential for sexual reproduction of flowering plants and plants that produce cones. Each pollen grain contains male gametes necessary for fertilisation. The scientific study of living and fossilised pollen grains is known as palynology. The male part of flowering plants is the stamen.