Flowers and bees
dog's mercury Mercurialis perennis. Picture from
Linnaeus book ”Blomstrens biläger” from 1750.
Different plant species have different methods to have their pollen transferred from flower to flower. The shape, colour and size of the flowers tell about the way they are pollinated. Plants with colourful petals or a strong scent are often pollinated by animals. They can for example attract bees, butterflies, beetles, birds or bats. Small inconspicuous flowers spread their pollen by the wind or are self-pollinated.
To attract insects or other animals the plants offer a reward such as nectar or pollen.
There is often a mutual dependency between plant and pollinator. Some plant species can be completely depending on one or a few insect species for their pollination, for example the ”star of Bethlehem”. In the same way an insect can be completely depending on one plant species for its survival.
In this interaction among species there are some dishonest plants that take advantage of the situation. They pretend to be one of the rewarding plants but do not give a reward. Many orchids, for example fly orchid, are fooling their pollinators.
The star of Bethlehem
Photo: Roland Moberg
In Madagascar there is an orchid with a spur, more than 30 cm long. It is called the Star of Bethlehem or Angraecum sesquipedale. When Darwin saw it in the 19th century, he realized that there must be a moth with almost as long a proboscis pollinating the orchid.
In 1903 such a moth was discovered in Madagascar, a moth given the name Xanthopan morgani ssp. praedicta. Praedicta means the predicted.
The pollination of the Star of Bethlehem takes place during night, and after a long time the pollination has been seen and filmed. The moth Xanthopan morganii praedicta pollinating the Star of Bethlehemn (new window)
Fly orchid – a dishonest orchid
The fly orchid, Ophrys insectifera, is an orchid growing in wet meadows in lime stone areas. There is no coincidence that the flowers resemble insects. They imitate the female of certain insects, the digger wasps. The scent of the flowers imitates that of a female digger wasp ready for mating. When the orchid is flowering the digger wasp males are fooled to try to mate with the flowers. The pollen that sticks to the insect's body can pollinate another plant of the same species, when the insect makes the same mistake again.
Fly orchid is a dishonest orchid since it fools the insects to visit them without offering a reward. It is believed that about a third of the world's 25 000 different orchid species are dishonest.