Pollination syndrome
[3] The naturalist Charles Darwin surmised that the flower of the orchid Angraecum sesquipedale was pollinated by a then undiscovered moth with a proboscis whose length was unprecedented at the time.
The anthers may produce a large number of pollen grains, while the stamens are generally long and protrude out of flower.
[5] Butterfly-pollinated flowers tend to be large and showy, pink or lavender in colour, frequently have a landing area, and are usually scented.
The flowers have simple nectar guides with the nectaries usually hidden in narrow tubes or spurs, reached by the long tongue of the butterflies.
So moth-pollinated flowers tend to be white, night-opening, large and showy with tubular corollas and a strong, sweet scent produced in the evening, night or early morning.
[6] Myophilous plants, those pollinated by flies, tend not to emit a strong scent, are typically purple, violet, blue, and white, and have open dishes or tubes.
Most beetle-pollinated flowers are flattened or dish shaped, with pollen easily accessible, although they may include traps to keep the beetle longer.
[10] Flowers pollinated by specialist nectarivores tend to be large, red or orange tubes with a lot of dilute nectar, secreted during the day.
[11] Bat-pollinated flowers in this part of the world tend to be large and showy, white or light coloured, open at night and have strong musty odours.
In the Americas pollinating bats are tiny creatures called glossophagines which have both the ability to hover as well as echolocate, and have extremely long tongues.
[11] Flowers in this part of the world are typically borne away from the trunk or other obstructions, and offer nectar for extended periods of time.
[12] A number of species of Marcgravia from Caribbean islands have evolved a special leaf just above the inflorescence to attract bats.
The epiphytic bean Mucuna holtonii employs a similar tactic, but in this species it is a specialised petal that acts as a sonar reflector.
[16][17] Many non-flying mammals are nocturnal and have an acute sense of smell, so the plants tend not to have bright showy colours, but instead excrete a strong odour.
[18] The Western-Australian endemic Honey possum (Tarsipes rostratus) is an unusual non-flying mammal pollinator in that it has adapted to feeding exclusively on pollen and nectar.
It is known to forage on a wide variety of plants (particularly in the families Proteaceae and Myrtaceae) including many with typical bird-pollinated flowers such as Calothamnus quadrifidus[19] and many species of Banksia.
[22] They are responses to common selection pressures exerted by shared pollinators or abiotic pollen vectors, which generate correlations among traits.
[33] Although a recent review concluded that there is "overwhelming evidence that functional groups exert different selection pressures on floral traits",[21] the sheer complexity and subtlety of plant-pollinator interactions (and the growing recognition that non-pollinating organisms such as seed predators can affect the evolution of flower traits) means that this debate is likely to continue for some time.
