Spore vs Seed
During pollination, pollen grains from a flower fall on the stigma of the same flower or another flower. They are stimulated by a sugary fluid on the stigma and starts germinating. The intine of the pollen grain grows out through a small pore in the extine to produce the pollen tube. Pollen tube grows down and enters the ovule through the micropyle. Then the apex of the pollen tube degrades and the two male nuclei are released into the ovule. The double fertilization takes place by the fusion of one male nucleus with the egg cell nucleus, giving rise to the diploid zygote, and fusion of the other male nucleus with the diploid secondary nucleus giving rise to the triploid primary endosperm nucleus. After the fertilization, the ovule becomes the seed.
What is a Spore?
Depending on the different types of spores, a plant can be homosporous or heterosporous. If the plant has only one type of spores, it is known as homospory. If the plant has two types of spores, a male and female spores, it is known as heterospory. Male spores are called microspores and female spores are called megaspores. Microspores are also called pollen grains. In flowering plants, microspores are found inside the pollen sac or the microsporangium. Microspores are very small, minute structures. They are almost like dust particles. Each microspore has one cell and two coats. Outermost coat is the extine, and the inner one is the intine. Extine is a tough, cutinized layer. Often it contains spinous outgrowths. Sometimes it can be smooth, as well. The intine is smooth, and it is very thin. It is mainly made up of cellulose. The extine contains one or more thin places known as the germ pores through which the intine grows out to form the pollen tube. The pollen tube elongates trough the gynoecium tissues carrying two male gametes in it. In flowering plants, the megaspore mother cell divides meiotically forming a tetrad of four megaspores in which the upper three megaspores degenerate.
What is a Seed?
After fertilization, the ovule develops in to the seed. The two integuments of the ovule become the two seed coats. The outer seed coat is called the testa, and the inner seed coat is called the tegmen. Some seeds contain only one seed coat. The stalk of the seed is developed from the funicle. Nucellus is generally being used up completely but, in some seeds, it may remain as a thin layer. Egg cell after fertilization gives rise to the embryo, and synergid and antipodal cells get completely disorganized after fertilization.
What is the difference between Spore and Seed?
• Spores are produced before fertilization by spore mother cells in order to carry out fertilization and seeds are developed from the ovule after fertilization.
• Pollens contain two coats, extine and intine, and the two coats the seed contains are known as the testa and tegmen.
• Microspores are found within the pollen sacs of another, and megaspores are formed inside the ovule, whereas the entire ovule becomes the seed after fertilization.
• Spores do not contain embryos inside whereas the seed contains an embryo inside.
• Microspores are minute dust like particles whereas seeds are not as small as that.