Crack Willow Salix fragilis
The Crack Willow is native to Europe (including Britain) and western Asia. It is particularly common along rivers. It was often cut at a height of 2 to 4 m, in an ancient practice called pollarding, to provide stakes for wattle fencing. The trees are now pollarded to stop branches falling into and blocking the river. The tree spreads along rivers naturally. Side twigs, if bent, will snap off cleanly with a crack, hence the name. Other Willows do not do this. If a twig snaps off, floats down the river and lodges in mud, it will root and grow.
Willows are pollinated by insects (Poplars are wind pollinated). Willows have male flowers on one tree and female flowers on another tree. Technically they are called ‘dioecious’ from the Greek meaning ‘2 households’. The flowers are in the form of catkins. Female and male catkins look different. Male catkins have anthers that carry bright yellow pollen. At the base of each flower is a pot of nectar. Insects, usually early bees, collect the nectar (to make honey) and, as they do so, get coated in pollen, which they then transfer to the female flower when they go to its nectar pot. Female catkins are greener, stay on the tree longer and eventually release seeds. Click on any photo to enlarge it.