Pollen, or pollen grains, is the set of microgametophytes produced by spermatophytes. In gymnosperms, it is produced in the male cones; in angiosperms, it is produced in the anthers. The main function of pollen is to transport the male gametophyte near the female gametophyte.
Pollen grains have a special wall made of sporopollenin, an extremely strong and stable polymer that protects the pollen as it moves from the stamens to the pistil in angiosperms, or from the male cone to the female cone in gymnosperms. If the pollen falls on a compatible pistil or female cone, it germinates, producing a pollen tube that carries the male germ to the ovule containing the female germ.
It may have a dusty appearance and consist of granules ranging in size from 2.5 μ to 0.2 mm, free from each other or agglomerated in tetrads, as in Ericaceae, or in agglutinated masses, as in Orchidaceae. Each granule has a bistratified wall composed of an exine (in which sporopollenin is the predominant component) and an endine (in which pectin predominates).
The external shape varies from species to species and is partly related to how the granules are transported during the pollination process. The color also varies from species to species: white, yellow, reddish-orange, brown or greenish-blue.
Pollen is very rich in proteins and is an important food source for many insects. The science that studies pollen is called palynology.
The mature pollen granule may consist of 2 to 3 cells or nuclei in angiosperms and 3 to many cells in gymnosperms, where the amount of pollen shed may also be considerable, resulting in what is known as “sulfur rain”. Upon contact with the ovule (in gymnosperms) or the stigma (in angiosperms), the pollen grains germinate by releasing the pollen tube, which penetrates the underlying tissues and transports the pollen nuclei to the oosphere, ensuring fertilization.
The viability of pollen, that is, its ability to germinate and shed the pollen envelope, varies from a few hours, as in certain Gramineae, to several months, as in Phoenix dactylifera. Pollen can cause severe allergic reactions (pollinosis), especially when it comes into contact with human mucous membranes.
Properties and benefits of pollen
Pollen is one of the richest substances in nature. Considered by many to be the most perfect food on earth in terms of its complete range of nutrients, it is presented as a food extremely rich in elements essential to the body and therefore to life, supplying what may be lacking at the moment. Moreover, since it is the raw material of royal jelly, it is not surprising that it is a highly energetic food (about 285 Kcal per 100g).
Each pollen grain is a biological unit that contains everything necessary for life:
- Water, in percentages ranging from 12 to 20%;
- A large amount of protein (20% on average), most of it in the form of amino acids (21 of the 23 known amino acids), many of which are essential;
- Sugars in amounts of 15 percent (glucose and fructose);
- Lipids (about 5%, variable content), most of which are essential fatty acids, 70% alpha-linoleic (omega 3), 3-4% linoleic (omega 6), 16-17% monounsaturated and saturated;
- Mineral salts such as potassium, silicon, iron, magnesium, sulphur, chlorine, calcium, manganese, phosphorus, copper;
- a large number of vitamins, especially of the B group (B1, B2, B3, B4, B5, B6, B7, B8, B9, B12), vitamins A, C, D, E, K, PP;
- Enzymes, coenzymes, growth hormones (estrogen, androgen, acetylcholine and other substances with antibiotic activity), pigments such as carotenoids, anthocyanins, etc.
Pollen is a living food that acts on the human being in two important contexts: growth and organic balance. It has always been used in natural medicine, especially as a dietary supplement, since pollen contains almost all the substances necessary for the development and growth of an organism.
The most noticeable effect in humans after regular administration is an increase in appetite and metabolism in general. In particular, it can be considered as a general restorative, especially in cases of excessive thinness and organic emaciation; several indications are reported in the literature for minor ailments: constipation, obstipation, colitis and intestinal infections, as well as having an invigorating and stimulating effect, ensuring a sense of well-being and euphoria.
It has an effective antianemic action, causing a rapid increase in the number of red blood cells and hemoglobin levels, making it particularly useful for vegetarians who may suffer a deficiency not so much of iron as of vitamin B12 (found almost exclusively in meat). The two monosaccharide sugars (glucose and fructose) have a strong energetic and protective capacity for the heart and liver.