pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...
wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ho ...
. Almost all
gymnosperm
The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...
s are anemophilous, as are many plants in the order
Poales
The Poales are a large order of flowering plants in the monocotyledons, and includes families of plants such as the grasses, bromeliads, and sedges. Sixteen plant families are currently recognized by botanists to be part of Poales.
Descriptio ...
, including
grasses
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns ...
,
sedges
The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...
, and rushes. Other common anemophilous plants are oaks,
pecans
The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia, ...
,
pistachios
The pistachio (, ''Pistacia vera''), a member of the cashew family, is a small tree originating from Central Asia and the Middle East. The tree produces seeds that are widely consumed as food.
''Pistacia vera'' is often confused with other spe ...
Juglandaceae
The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia.
The nine or ten genera in the family have ...
(hickory or walnut family). Approximately 12% of plants across the globe are pollinated by anemophily, including
cereal crops
A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
like
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...
, and
oats
The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human co ...
firs
Firs (''Abies'') are a genus of 48–56 species of evergreen coniferous trees in the family Pinaceae. They are found on mountains throughout much of North and Central America, Europe, Asia, and North Africa. The genus is most closely related to ...
are wind-pollinated, and.
Syndrome
Features of the wind-pollination syndrome include a lack of scent production, a lack of showy floral parts (resulting in small, inconspicuous flowers), reduced production of nectar, and the production of enormous numbers of pollen grains. This distinguishes them from
entomophilous
Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, some ...
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
s and
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
s respectively).
Anemophilous pollen grains are smooth, light, and non-sticky, so that they can be transported by air currents. Wind-pollinating plants have no predisposition to attract pollinating organisms. They freely expel a myriad of these pollen grains, and only a small percentage of them ends up captured by the female floral structures on wind-pollinated plants. They are typically in diameter, although the pollen grains of ''
Pinus
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden ...
'' species can be much larger and much less dense. Anemophilous plants possess lengthy, well-exposed stamens to catch and distribute pollen. These stamens are exposed to wind currents and also have large, feathery stigma to easily trap airborne pollen grains. Pollen from anemophilous plants tends to be smaller and lighter than pollen from entomophilous ones, with very low nutritional value to insects due to their low protein content. However, insects sometimes gather pollen from staminate anemophilous flowers at times when higher-
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
pollens from entomophilous flowers are scarce. Anemophilous pollens may also be inadvertently captured by bees'
electrostatic
Electrostatics is a branch of physics that studies electric charges at rest ( static electricity).
Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amb ...
field. This may explain why, though bees are not observed to visit
ragweed
Ragweeds are flowering plants in the genus ''Ambrosia'' in the aster family, Asteraceae. They are distributed in the tropical and subtropical regions of the Americas, especially North America,pollen is often found in
honey
Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
made during the ragweed floral bloom. Other flowers that are generally anemophilous are observed to be actively worked by bees, with solitary bees often visiting
grass
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
flowers, and the larger
honeybee
A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cosm ...
s and
bumblebee
A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related genera ...
s frequently gathering pollen from corn tassels and other grains.
Anemophily is an adaptation that helps to separate the male and female reproductive systems of a single plant, reducing the effects of
inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
. It often accompanies dioecy – the presence of male and female reproductive structures on separate plants.
Allergies
Almost all pollens that are
allergen
An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies.
In technical terms ...
s are from anemophilous species. People allergic to the pollen produced by anemophilous plants often have symptoms of hay fever. Grasses ( Poaceae) are the most important producers of aeroallergens in most temperate regions, with lowland or meadow species producing more pollen than upland or moorland species. In Morocco, it was found that asthma caused by pollen from Poaceae accounted for 10% of the clinical respiratory diseases that patients faced. The nature of how species of Poaceae grasses flower results in an increase in the time that the allergenic pollen circulates through the air, which is not favorable to people who are hypersensitive to it.