How does wind pollination work in conifers?

All conifers rely on wind for pollination, a process in which pollen is released from male cones and carried through the air to female cones. Because this method is imprecise, conifers produce enormous quantities of pollen to ensure successful fertilization.123

The mechanism for capturing pollen varies by species:

• Pollination Droplets: Many conifers, such as those in the Pinaceae and Podocarpaceae families, exude a pollination droplet from the ovule. Pollen grains often feature air bladders that help orient them within this droplet; as the droplet is withdrawn into the ovule, it pulls the pollen into position for the pollen tube to penetrate the nucellus.1
• Direct Contact: In other species, such as the Douglas fir, pollen lands on a stigmalike growth on the micropyle. For the Araucariaceae family, pollen grains land on the female cone scales and reach the micropyle by burrowing through the scales.1
• Simplified Grains: Some conifers lack air sacs and pollination droplets entirely; their pollen grains are spherical and can extend a pollen tube from any point on their surface.1