Petal Reduction: Petals are typically small and dull (green or brown), as the plant does not need to invest energy in attracting animal vectors.
Exposed Anthers: Anthers are held on long, flexible filaments that hang outside the flower. This exposure allows even light breezes to shake the pollen free into the air currents.
Pollen Volume and Weight: These plants produce vast quantities of light, smooth pollen. Since wind dispersal is random, a high volume of buoyant pollen increases the probability that some grains will land on a distant flower.
Feathery Stigmas: The stigmas are large and feathery, hanging outside the flower to maximize the surface area available to 'catch' airborne pollen as it drifts by.
| Feature | Insect-Pollinated | Wind-Pollinated |
|---|---|---|
| Petals | Large, bright, and scented | Small, dull, and scentless |
| Nectar | Produced as a reward | Not produced (energy saving) |
| Stigma | Small and sticky; internal | Large and feathery; external |
| Pollen | Sticky, spiked, and few | Smooth, light, and numerous |
| Anthers | Firmly fixed; internal | Dangling on long filaments; external |
Functional Linking: When describing a structure, always state its function. For example, do not just say 'feathery stigma'; say 'feathery stigma to provide a large surface area for catching wind-borne pollen'.
Diagram Identification: Look for the position of the anthers. If they are tucked inside a cup of petals, it is insect-pollinated; if they are dangling outside, it is wind-pollinated.
Energy Conservation: Remember that wind-pollinated plants lack scent and nectar because producing them would be a 'waste of energy' given their pollination vector doesn't have senses.
Pollen Types: Be prepared to identify pollen under a microscope. Spiky pollen is for sticking to insects; smooth pollen is for aerodynamic wind travel.
Pollination vs. Fertilisation: A common error is treating these as synonyms. Pollination is the arrival of pollen on the stigma; fertilisation is the fusion of the male and female nuclei following pollen tube growth.
Presence of Petals: Students often assume wind-pollinated flowers have 'no petals'. They usually do have petals, but they are highly reduced, small, and green, making them look like leaves or sepals.
Gamete Misnaming: Avoid calling pollen the 'male gamete'. Pollen is the vector that contains the male nucleus; the nucleus itself is the gamete.
