Agents of natural pollination

Personal notes for RHS Level 2 Certificate in the Principles of Plant Growth and Development

Unit 1: Plant Science 1: Pollination and fertilisation: AO1

The agents of natural pollination are diverse and can be broadly classified into two categories: biotic and abiotic.

𝐁𝐢𝐨𝐭𝐢𝐜 𝐚𝐠𝐞𝐧𝐭𝐬 include pollinating animals such as bees, moths, flies, and birds.

The biotic agents are attracted to a flower due to such features as its colour, shape, or aroma.

The visitor to a flower then becomes a potential agent for pollination transfer, with the pollen from the male reproductive organ, known as the anther, dusted onto the animal's body. Should the animal then visit another flower of the same species, this pollen may then be inadvertently brushed onto the stigma, the female reproductive organ.

Whether pollination successfully leads to fertilisation on the same flower, or a different flower of the same species will depend on the species visited.


Flower shape can be a determining factor as to which species are able to visit the flower. Some flowers have evolved to perfectly match specific animal species. Perhaps, the most well-known example of this is the Star orchid (Angraecum sesquipedale), which is pollinated by the long-tongued moth commonly known as Morgan's predicted Sphinx moth. In 1862, Charles Darwin examined this orchid, predicting (supported by Alfred Russel Wallace) that a long-tongued moth would be found that pollinated it; no moth with that extreme length of tongue was known at the time.

Then, in 1903, he was proven correct when a long-tongued moth, Xanthopan morganii praedicta was discovered. It was so named because its occurrence had been predicted.

𝐀𝐛𝐢𝐨𝐭𝐢𝐜 𝐚𝐠𝐞𝐧𝐭𝐬 include wind and water.

Wind-pollinated plants produce large amounts of pollen that is light in weight and easily carried by the wind. Some examples of wind-pollinated plants in the UK include willow (Salix), alder (Alnus), and birch (Betula)


Water-pollinated plants, on the other hand, release their pollen into the water, where it is carried to the female reproductive organs. Some examples of water-pollinated plants in the UK include water thyme (Hydrilla), ditch grasses (Ruppia), and waterweeds (Elodea).

Photo: Bumblebee (Bombus species) visiting Cowslip (Primula veris).