ORCHID'S REPRODUCTION

Reproduction

Bumblebee Orchid (Ophrys bombyliflora)
It is in the variety and the refinement of their reproductive methods that orchids truly amaze. On many orchids, the lip (labellum) serves as a landing pad for flying insects. The labellum is sometimes adapted to have a color and shape which attracts particular male insects via mimicry of a receptive female insect. Some orchids are reliant solely on this deception for pollination. After pollination, the epigynous ovary starts developing and produces a many-seeded capsule.
•The Lady's Slipper (Paphiopedilum) has a deep pocket that traps visiting insects, with just one exit. Passage through this exit leads to pollinia being deposited on the insect.
•Many neotropical orchids are pollinated by male orchid bees, which visit the flowers to gather volatile chemicals they require to synthesize pheromonal attractants. Each type of orchid places the pollinia on a different body part of a different species of bee, so as to enforce proper cross-pollination.
•A Eurasian genus Ophrys has some species that look and smell so much like female bumblebees that male bees flying nearby are irresistibly drawn in and attempt to mate with the flower, such as with the Bumblebee Orchid (Ophrys bombyliflora). The viscidium, and thus pollinia, stick to the head or the abdomen of the bumblebee. On visiting another orchid of the same species, the bumblebee pollinates the sticky stigma with the pollinia. The filaments of the pollinia have, during transport, taken such position that the waxy pollen are able to stick in the second orchid to the stigma, just below the rostellum. Such is the refinement of the reproduction. If the filaments had not taken the new position on the bee, the pollinia could not have pollinated the original orchid. Other species of Ophrys are mimics of different bees or wasps, and are also pollinated by males attempting to mate with the flowers, and other orchid genera practice similar deception.
•An underground orchid in Australia, Rhizanthella slateri, never sees the light of day, but depends on ants and other terrestrial insects to pollinate it.
•Many Bulbophyllum species stink like rotting carcasses, and the flies they attract assist their reproduction.
•Catasetum saccatum, a species discussed briefly by Darwin actually launches its viscid pollen sacs with explosive force, when an insect touches a seta. He was ridiculed for reporting this by the naturalist Thomas Huxley.
•Some Phalaenopsis species in Malaysia are known to use subtle weather cues to coordinate mass flowering.
•Some Phalaenopsis, Dendrobium and Vanda species produce keiki, offshoots or plantlets formed from one of the nodes along the stem, through the accumulation of growth hormones at that point.
The filaments of the pollinia of some orchids dry up if they haven’t been visited by an insect. This way, the waxy pollen falls on the stigma causing the orchid to self-fertilize.
•Holcoglossum amesianum, native to China's Yunnan province, reproduces in a hermaphroditic manner, fertilizing itself by rotating its anther and insert it into the flower's stigma cavity. This mode of pollination is likely due to the lack of wind and insects in the region where this species grows. The Bee orchid uses a similar method of selfpollination.

SOURCE:WIKIPEDIA