Flowers come in all sorts of shapes and sizes. The vast diversity in floral morphology in the Angiosperms is intimately linked with plant-pollinator interactions (Aigner 2006). Plants exhibit these floral features to attract pollinators and maximise pollination; in turn pollinators visit flowers for the beneficial goodies they offer to the pollinator (pollen, nectar).
Floral traits are considered to be principal attractants for pollinators, acting to advertise rewards and aid pollinators in recognising suitable plants to visit (Dafni 1992). The effectiveness of this advertisement can depend on traits such as colour, shape, size, number of flowers, scent production, pollen presentation and inflorescence architecture.
An interesting situation arises when plants use a ‘common advertisement’ style… but don’t in fact produce the expected reward! Devious.
Plants that look like they produce a reward yet don’t come through with the goods are known as ‘mimics’ or partake in ‘deception’. This mimicry can be ‘sexual mimicry’ (a plant might resemble an insect’s mate) or ‘food deceptive’ where the plant looks like other plants that produce pollen or nectar.
Whilst olfactory cues such as scent are important in sexual mimicry, visual cues are considered central to food deceptive species, which exploit the pollinator’s attraction too, and recognition of, these common advertising signals (Dafni 1992).
Deceptive plants (the ‘mimics’) often have a ‘model’.
Non- rewarding flowers are successful only if the pollinator is deceived twice, once to remove pollen and once to deposit it (Dafni 1992). Food mimicry systems are always frequency-dependent (Dafni 1984), and the mimic needs to be scattered within a larger population of its models.
If more mimics occur than models, most plants will be unrewarding, and pollinators are likely to seek an alternative food source or leave the floral patch in search of a more rewarding area (Johnson et al. 2003), thereby reducing the chances of successful pollination to all players.
These photos (below) represent what is commonly thought to be a group of co-flowering models for a mimetic species.
Can you guess who are the models and who are the mimics?
Aigner PA (2006) The evolution of specialized floral phenotypes in a fine-grained
pollination environment. In ‘Plant-pollinator interactions, from specialization to generalization’. (Eds NM Waser, J Ollerton) pp. 23 – 47. (The University of Chicago Press: Chicago).
Dafni A (1984) Mimicry and deception in pollination. Annual Review of Ecological Systematics 15, 259 – 278.
Dafni A (1992) ‘Pollination Ecology, a practical approach’. (Oxford University Press: New York).
Johnson SD, Peter CI, Nilsson LA, Agren J (2003) Pollination success in a deceptive orchid is enhanced by co-occurring rewarding magnet plants. Ecological Society of America 84, 2919 – 2927.