Trees with Wind-Pollinated Flowers

Wind pollination is an inefficient option for a tree, as there is a very low probability of a pollen grain landing by chance on the stigma of suitable recipient flower. But, on the other hand, suitable insect pollinators don't thrive in the British climate, particularly in the cooler countryside. Hence a high percentage of native or naturalised British tree species are wind-pollinated. Their flowers are not so flashy as those of insect-pollinated species, but at close range they reveal an intricate beauty. Below are nine such wind-pollinated species.

Goat Willow (Salix caprea), one of the so-called 'pussy willows' has one of the most striking wind-pollinated flowers. The female flower before opening is soft enough to stroke (in the first picture the styles have extended and the yellow stigmas pushed through the grey hairs). The male flower is equally striking with long yellow-anthered stamens.

White Willow (Salix alba) has longer catkins closer to the common perception of a catkin, though in this case not hanging. This is the male flower, the female flowers being much less conspicuous.

Hazel (Corylus avellana) has some of the longest catkins of British trees. Hazel is a common woodland species, and is traditionally coppiced for hurdle-making. A related species, Turkish Hazel, is a common street tree, forming an elegant conical crown.

Black Poplar (Populus nigra) is a native tree that has become decidedly uncommon in its natural form, having been largely supplanted in floodplains by fast-growing hybrid forms planted for timber. All poplars have catkins, and the male flowers are nearly always red.

Common Ash (Fraxinus excelsior) is one of our most widespread native trees (though serious threatened by ash dieback disease), and has very distinctive wide-branching flowers.

Huntingdon Elm (Ulmus x hollandica), like many other elms, has beautiful delicate purple flowers opening very early in the spring. Native elms are still widespread as small trees, as the beetles which bring Dutch Elm Disease do not invade their bark until the trunk is around 15cm in diameter. The Huntingdon Elm is a widely-planted hybrid which has some resistance to DED, though the tree on which the flowers in the photo blossomed sadly appears to have succumbed.

Walnut (Juglans regia) is I think my favourite wind-pollinated tree flower, because it is so, so delicate and tiny, particularly compared with the resultant fruit. Related species, such as Pecan and Hickory, are also wind-pollinated.

London Plane (Platanus x hispanica) has really quite dramatic and unusual red flowers, but the colour soon fades and the flower cluster slowly develops into the distinctive globular fruit.

Sycamore (Acer pseudoplatanus) belongs to the maple family, which like the ashes has the unusual feature that some species are insect-pollinated and some wind-pollinated. The Sycamore, with its characteristic hanging panicles, is wind-pollinated, whereas the Norway Maple, with rather similar leaves, has sizeable yellow insect-pollinated flowers.