Blowin’ in the Wind

The male cones of Scots pine are just beginning to release their pollen now, and if you give a branch with ripe pollen sacs a sharp tap it will more or less disappear in a cloud of pollen. Conifers depend on the wind to deliver their pollen, so tend to produce vast quantities of the stuff to ensure that at least a few pollen grains make the successful journey to an ovule, fertilise it and produce a seed. The studio shot of larch pollen here (middle picture), with the yellow pollen sacs releasing pollen that’s landing on the pink young female cone, where the seeds will eventually develop, gives a false impression of the likely success rate. The chance of an individual pollen grain effecting a fertilisation is probably one in several million. The longer the pollen stays aloft, the better its chance in this lottery, so conifer pollen is slung between two balloon-like air sacs that increase its aerial buoyancy. You can see these in the top two microscope photos, at x100 and x400 magnification. They certainly seem to do the job- researchers have collected pine pollen from North American conifer forests on sticky traps mounted on weather ships in mid-Atlantic.