It is now known that pollination systems are predominantly specialized: plants rely on a single species or a few ecologically analogous species for pollination.

Most significantly, the diversity of pollination systems increases primarily with floral complexity and secondarily with genus size.

Thus, Aristea ( approximately 56 species ), which has radially symmetric, mostly blue flowers, has three different pollination systems, whereas Sparaxis ( 15 species ), with both zygomorphic and secondarily radially symmetric flowers, in a variety of colors, exhibits five different pollination systems, and Gladiolus, with a similar array of floral types but over two hundred species, exploits seven different pollination systems, some of which have evolved multiple times.

As is usual in predominantly specialist pollination systems, floral attractants and rewards correlate closely with pollinator profile, resulting in the development of distinct floral syndromes.

Furthermore, unrelated clades have evolved more than once into rather similar pollination systems:

Another study found that cropping systems that required heavy use of chemical amendments ( e. g., the widespread broadcasting of pesticides and glyphosate, a practice ubiquitously found throughout the United States and Canada ) had significantly greater levels of pollination deficits, whereas organic fields of the same crop ( Canola ) witnessed no pollination deficits.

Certain aspects of these reproductive parts mirror the pollination systems in the Orchid family and represent a case of parallel evolution though both groups are quite unrelated and have developed similar, though not identical means to achieve the ultimate goal of pollination and therefore reproduction.

Two sorts of flowers are found in the family reflecting different breeding systems: some taxa have inconspicuous perianths and reproduce largely by self pollination.

Darwin was diverted by spending hours considering the variety of wild orchids to be found along the shore, continuing an interest in insect pollination dating back to the late 1830s when on the recommendation of Robert Brown he had read Christian Konrad Sprengel on the subject.

The stamens are usually found around the style, either aggregated densely or fused into a tube, probably an adaptation in association with the plunger ( brush ; or secondary ) pollination that is common among the families of the order, wherein pollen is collected and stored on the length of the pistil.

Possible solutions to the cross pollination problem are to plant a wider refuge field or plant varieties of corn that bloom at different times than the Bt fields do.

Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax.

Bees gathering nectar may accomplish pollination, but bees that are deliberately gathering pollen are more efficient pollinators.

Its flowers are attractive to bees, which are important for gardens with an abundance of plants in need of pollination.

Many of the domestic cultivars do not produce hips, as the flowers are so tightly petalled that they do not provide access for pollination.

The distinctively flavored compounds are found in the fruit, which results from the pollination of the flower.

Many plants that are pollinated by insects, bats, or birds have highly specialized flowers modified to promote pollination by a specific pollinator that is also correspondingly adapted.

White oaks are unable to discriminate against pollination by other species in the same section.

This prevents pollination and the development of viable seeds, which are sometimes considered undesirable for brewing beer owing to the potential for off-flavors arising from the introduction of fatty acids from the seeds.

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.

Some species are pests because in their larval stages they can damage domestic crops or trees ; however, some species are agents of pollination of some plants, and caterpillars of a few butterflies ( e. g., Harvesters ) eat harmful insects.

Flowers are kept closed before and after pollination to prevent cross pollination.

The male flowers emerge first, followed shortly afterward by the female flowers, which grow into capitula, which are capable of pollination just three days later.

* Bee – flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax.

Cabbage heads are generally picked during the first year of the plants ' life cycles, but those intended for seed are allowed to grow a second year, and must be kept separated from other cole crops to prevent cross pollination.

Fig species are characterized by their unique inflorescence and distinctive pollination syndrome, which utilizes wasp species belonging to the Agaonidae family for pollination.

Their flowers are among the most diverse and unusual, although often very small, and specialize in using tiny insects such as gnats or Chalcid wasps for pollination.

Megachilid bees are among the world's most efficient pollinators because of their energetic swimming-like motion in the reproductive structures of flowers, which moves pollen, as needed for pollination.

The cones are among the smallest of any conifer, 2 – 3 mm long, green ripening brown in about 8 months from pollination, and have 4 scales arranged in two opposite pairs.

Well-documented studies of non-flying mammal pollination now involve at least 59 species of mammal distributed among 19 families and six orders ( Carthewa 1997 ).

The cones are among the smallest of any conifer, 2-3 mm long, green ripening brown in about 7-8 months from pollination, and have four scales arranged in two opposite pairs, each scale bearing a short bract ; the upper pair of scales bearing two small winged seeds.

It is estimated that one third of the human food supply depends on insect pollination, most of which is accomplished by bees, especially the domesticated European honey bee.

The most recognized pollinators are the various species of bees, which are plainly adapted to pollination.

Millions of hives of honey bees are contracted out as pollinators by beekeepers, and honey bees are by far the most important commercial pollinating agents, but many other kinds of pollinators, from bluebottle flies, to bumblebees, orchard mason bees, and leaf cutter bees are cultured and sold for managed pollination.

As in most sedges, pollination is by wind, not insects, and the mature fruits after release are distributed by water.

However most pollination occurs at night.

Unlike most Rubus species, the cloudberry is dioecious, and fruit production by a female plant requires pollination from a male plant.

The most common form of abiotic pollination, anemophily, is pollination by wind.

This form of pollination is predominant in grasses, most conifers, and many deciduous trees.

Honey bees are usually the most widely chosen insects in most managed pollination situations.

The most significant native species is Osmia lignaria ( the orchard mason bee or blue orchard bee ), which is sold commercially for use in orchard crop pollination, and which can be attracted to nest in wooden blocks with holes drilled in them ( which are also sold commercially for this purpose ).

Flower-feeding thrips may be responsible for pollination while feeding, but their most obvious contribution to their ecosystem remains the damage they can cause during feeding.

The fruit is a slender reddish brown acorn 2-3. 5 cm long and 1-1. 5 cm broad, with the basal quarter enclosed in a cupule ; unusually for a red oak, the acorns mature about 7 – 8 months after pollination ( most red oak acorns take 18 months to mature ).

Unlike most modern grapes it is a pistillate female and so needs to be planted next to male vines from a close sibling variety to achieve pollination.

Maturation takes 6 – 8 months from pollination in most Pinaceae genera, but 12 months in cedars and 18 – 24 months ( rarely more ) in most pines.

Hand pollination is the most reliable method in commercially grown Vanilla.

However, the most efficient pollination is accomplished by a few species who specialize in sonication or buzz pollination.

In many land plants, including most gymnosperms and all angiosperms, the male gametophytes ( pollen grains ) are the primary mode of dispersal, for example via wind or insect pollination, eliminating the need for water to bridge the gap between male and female.