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Pollen is a powdery substance consisting of pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of coniferous plants. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archaeology, and forensics. Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of another in cross-pollination.[1] In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower.[1]

Pollen is infrequently used as food and food supplement. Because of agricultural practices, it is often contaminated by agricultural pesticides.[2]

Antihistamines are effective at treating mild cases of pollinosis; this type of non-prescribed drugs includes loratadine, cetirizine and chlorpheniramine. They do not prevent the discharge of histamine, but it has been proven that they do prevent a part of the chain reaction activated by this biogenic amine, which considerably lowers hay fever symptoms.

Decongestants can be administered in different ways such as tablets and nasal sprays.

Allergy immunotherapy (AIT) treatment involves administering doses of allergens to accustom the body to pollen, thereby inducing specific long-term tolerance.[28] Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergy immunotherapy represents the only causative treatment for respiratory allergies.

Nutrition

Most major classes of birch and alder, and in late summer wormwood and different forms of hay. Grass pollen is also associated with asthma exacerbations in some people, a phenomenon termed thunderstorm asthma.[22]

In the US, people often mistakenly blame the conspicuous goldenrod flower for allergies. Since this plant is entomophilous (its pollen is dispersed by animals), its heavy, sticky pollen does not become independently airborne. Most late summer and fall pollen allergies are probably caused by ragweed, a widespread anemophilous plant.[23]

Arizona was once regarded as a haven for people with pollen allergies, although several ragweed species grow in the desert. However, as suburbs grew and people began establishing irrigated lawns and gardens, more irritating species of ragweed gained a foothold and Arizona lost its claim of freedom from hay fever.

Anemophilous spring blooming plants such as oak, birch, hickory, pecan, and early summer grasses may also induce pollen allergies. Most cultivated plants with showy flowers are entomophilous and do not cause pollen allergies.

The number of people in the United States affected by hay fever is between 20 and 40 million,[24] and such allergy has proven to be the most frequent allergic response in the nation. There are certain evidential suggestions pointing out hay fever and similar allergies to be of hereditary origin. Individuals who suffer from eczema or are asthmatic tend to be more susceptible to developing long-term hay fever.[25]

In Denmark, decades of rising temperatures cause pollen to appear earlier and in greater numbers, as well as introduction of new species such as ragweed.[26]

The most efficient way to handle a pollen allergy is by preventing contact with the material. Individuals carrying the ailment may at first believe that they have a simple summer cold, but hay fever becomes more evident when the apparent cold does not disappear. The confirmation of hay fever can be obtained after examination by a general physician.[27]

Antihistamines are effective at treating mild cases of pollinosis; this type of non-prescribed drugs includes loratadine, cetirizine and chlorpheniramine. They do not prevent the discharge of histamine, but it has been proven that they do prevent a part of the chain reaction activated by this biogenic amine, which considerably lowers hay fever symptoms.

Decongestants can be administered in different ways such as tablets and nasal sprays.

Allergy immunotherapy (AIT) treatment involves administering doses of allergens to accustom the body to pollen, thereby inducing specific long-term tolerance.Decongestants can be administered in different ways such as tablets and nasal sprays.

Allergy immunotherapy (AIT) treatment involves administering doses of allergens to accustom the body to pollen, thereby inducing specific long-term tolerance.[28] Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergy immunotherapy represents the only causative treatment for respiratory allergies.

Most major classes of predatory and parasitic arthropods contain species that eat pollen, despite the common perception that bees are the primary pollen-consuming arthropod group. Many Hymenoptera other than bees consume pollen as adults, though only a small number feed on pollen as larvae (including some ant larvae). Spiders are normally considered carnivores but pollen is an important source of food for several species, particularly for spiderlings, which catch pollen on their webs. It is not clear how spiderlings manage to eat pollen however, since their mouths are not large enough to consume pollen grains.[citation needed] Some predatory mites also feed on pollen, with some species being able to subsist solely on pollen, such as Euseius tularensis, which feeds on the pollen of dozens of plant species. Members of some beetle families such as Mordellidae and Melyridae feed almost exclusively on pollen as adults, while various lineages within larger families such as Curculionidae, Chrysomelidae, Cerambycidae, and Scarabaeidae are pollen specialists even though most members of their families are not (e.g., only 36 of 40,000 species of ground beetles, which are typically predatory, have been shown to eat pollen—but this is thought to be a severe underestimate as the feeding habits are only known for 1,000 species). Similarly, Ladybird beetles mainly eat insects, but many species also eat pollen, as either part or all of their diet. Hemiptera are mostly herbivores or omnivores but pollen feeding is known (and has only been well studied in the Anthocoridae). Many adult flies, especially Syrphidae, feed on pollen, and three UK syrphid species feed strictly on pollen (syrphids, like all flies, cannot eat pollen directly due to the structure of their mouthparts, but can consume pollen contents that are dissolved in a fluid).[29] Some species of fungus, including Fomes fomentarius, are able to break down grains of pollen as a secondary nutrition source that is particularly high in nitrogen.[30] Pollen may be valuable diet supplement for detritivores, providing them with nutrients needed for growth, development and maturation.[31] It was suggested that obtaining nutrients from pollen, deposited on the forest floor during periods of pollen rains, allows fungi to decompose nutritionally scarce litter.[31]

Some species of Heliconius butterflies consume pollen as adults, which appears to be a valuable nutrient source, and these species are more distasteful to predators than the non-pollen consuming species.Heliconius butterflies consume pollen as adults, which appears to be a valuable nutrient source, and these species are more distasteful to predators than the non-pollen consuming species.[32][33]

Although bats, butterflies and hummingbirds are not pollen eaters per se, their consumption of nectar in flowers is an important aspect of the pollination process.

Bee pollen for human consumption is marketed as a food ingredient and as a dietary supplement. The largest constituent is carbohydrates, with protein content ranging from 7 to 35 percent depending on the plant species collected by bees.[34]

Honey produced by bees from natural sources contains pollen derived p-coumaric acid,[35

Honey produced by bees from natural sources contains pollen derived p-coumaric acid,[35] an antioxidant and natural bactericide that is also present in a wide variety of plants and plant-derived food products.[36]

The U.S. Food and Drug Administration (FDA) has not found any harmful effects of bee pollen consumption, except from the usual allergies. However, FDA does not allow bee pollen marketers in the United States to make health claims about their produce, as no scientific basis for these has ever been proven. Furthermore, there are possible dangers not only from allergic reactions but also from contaminants such as pesticides[2] and from fungi and bacteria growth related to poor storage procedures. A manufacturers's claim that pollen collecting helps the bee colonies is also controversial.[37]

Pine pollen (송화가루; Songhwa Garu) is traditionally consumed in Korea as an ingredient in sweets and beverages.[38]

The growing industries in pollen harvesting for human and bee consumption rely on harvesting pollen baskets from honey bees as they return to their hives using a pollen trap.[39] When this pollen has been tested for parasites, it has been found that a multitude of pollinator viruses and eukaryotic parasites are present in the pollen.[40][41] It is currently unclear if the parasites are introduced by the bee that collected the pollen or if it is from contamination to the flower.[41][42] Though this is not likely to pose a risk to humans, it is a major issue for the bumblebee rearing industry that relies on thousands of tonnes of honey bee collected pollen per year.[43] Several sterilization methods have been employed, though no method has been 100% effective at sterilisation without reducing the nutritional value of the pollen [44]

Forensic palynology

In some Native American religions, pollen was used in prayers and rituals to symbolize life and renewal by sanctifying objects, dancing grounds, trails, and sandpaintings. It may also be sprinkled over heads or in mouths. Many Navajo people believed the body became holy when it traveled over a trail sprinkled with pollen.[50]

Pollen grain staining

For agricultural res

In some Native American religions, pollen was used in prayers and rituals to symbolize life and renewal by sanctifying objects, dancing grounds, trails, and sandpaintings. It may also be sprinkled over heads or in mouths. Many Navajo people believed the body became holy when it traveled over a trail sprinkled with pollen.[50]

Pollen grain stainingFor agricultural research purposes, assessing the viability of pollen grains can be necessary and illuminating. A very common, efficient method to do so is known as Alexander's stain.[51] This differential stain consists of ethanol, malachite green, distilled water, glycerol, phenol, chloral hydrate, acid fuchsin, orange G, and glacial acetic acid.[52] In angiosperms and gymnosperms non-aborted pollen grain will appear red or pink, and aborted pollen grains will appear blue or slightly green.

See also