Orchids pollination

The shapes, colors and fragrances of the orchids are the result of coevolution with animal pollinators. Coryanthes leucocorys is a species that has developed one of the most fascinating mechanisms of pollinator attraction, which is by means of a fluid-filled sac.

Generally, the species flower only once a year and always around the same time, which is determined by environmental factors such as the decrease or increase in temperature, increase in the hours of daylight, seasonal changes and variations in humidity. The flowers can remain open from one day (if Sobralia) to over three months (as in Paphiopedilum and Phalaenopsis). The artificial hybrids can flower two or more times per year.

Of the orchid species, 97 percent require a pollinator in order to carry out the transfer of pollen from one plant to the pistil of another individual. Then fertilization occurs, followed by the formation of seeds.

Keep in mind that the pollen of orchids is grouped in compact masses called pollinia (singular: pollinium), so that by itself, or by wind, pollen can not disperse from one flower to another. Therefore pollinators are essential to ensure its sexual reproduction. These pollinators are diverse and, depending on the species in question, can be flies, mosquitoes, bees, wasps, beetles, and birds (especially hummingbirds).

The bestiality that characterizes the orchids assumes that animal pollinators visit flowers regularly and stop at them long enough, that the anthers and stigma are galled or played with some frequency, and that the former adhere to visitors as perfectly as you can get, with proper security to the stigmas of other flowers.

The result depends crucially on zoophilous animals that can recognize the flowers from a distance and of their being compelled to visit the flowers of the same species for a while. Zoophilic flowers, then, must have attractive products (primers, such as pollen and nectar), means of claim (such as smells and colors) and viscous pollen or adherent.

Many species of orchids reward pollinators with food (e.g., nectar, hair food or oils) and other compounds, such as waxes, resins and fragrances. These rewards, in turn, reinforce the behavior of pollinators. However, specialization in one type of pollinator ensures a more efficient transfer of pollen, and an increasing specialization on morphological and structural orchid flowers is found to ensure the attraction of a single species of insect.

For that reason, the orchid flowers are extremely varied and can attract a wide variety of insects (bees, wasps, flies, butterflies, and moths) as well as birds, bats or toads for pollination. Some attract general visitors, but many are quite specialized, attracting only one or a few species as pollinators.

Pollen, nectar or floral fragrances can be used as a reward for pollination, while some flowers (e.g., Cypripedium) manipulate their pollinators and do not provide any reward. Some species of Ophrys and Cryptostylis mimic the shape and the smell of female bees, wasps, and flies, and are pollinated when males try to mate with the flower (a phenomenon called pseudocopulation).

Generally, the lip acts as a landing platform and provides visual and tactile signals that guide the pollinator. The polynya is attached to the body of the pollinator, and is often deposited on the stigma (usually a depression in the bottom of the column) of the next flower visited.

Gender Coryanthes has a lip like a pocket that is filled with a fluid secreted by the column, a bee that falls into this fluid must travel through a tunnel, forcing pollinium to deposit on its body. The transfer of pollen within the polynya is an apparent adaptation to ensure fertilization of many of the tremendous number of eggs.

In some species pollination is a fairly rare event, and the flowers can remain functional and showy for many days. Wilting of the perianth occurs rapidly only after fertilization.

Angraecum sesquipedale, an orchid from Madagascar, is also known for its pollination biology. This species has a spur 20 to 35 cm long. Following a prediction made by Charles Darwin in 1862, there is an illustration of pollination of an Angraecum sesquipedale by a hypothetical moth with a long proboscis. The drawing was made in 1867 by Alfred Russell Wallace. In 1903 the moth was discovered in Madagascar and named Xanthopan morgani.