Catkins are small clusters of flowers and can be seen on some trees. My favourite of all catkins are found on the Goat Willow. Most of us know this tree as the pussy willow because its catkins look like cat’s paws. These are the male catkins before they come into full flower and this “fir coat” helps to keep the developing reproductive parts warm. Pussy willows emerge in early spring when it’s still quite cold, but when the sun shines, the temperature in the centre of the catkin can rise above air temperatures by trapping the heat from the sun with its insulating hairs. This additional warming aids in the development of the pollen.
The caterpillars of that elusive and beautiful butterfly-the Purple Emperor- prefer to feed on Goat willow. In fact, willows producing large amounts of strongly scented nectar which bees and flies are readily drawn to. They are pollinated by insects, whereas other catkin-producing trees rely on the breeze to disperse the pollen grains.
Some trees like Alder, Hazel, Silver Birch and Hornbeam have both female and male flowers(catkins) on the same tree. Others, mainly Ash, Yew and White Poplar have female and male flowers on separate trees. Let’s look, briefly at Alder and Hazel.
Alder is the only deciduous tree that produces cone-like structures found wild in Britain. It is these cones that prove so attractive to Siskins and Redpolls in winter. Both male and female catkins are borne on the same tree having been formed the previous year. The following spring, male catkins swell and open slightly to produce pollen. Wind dispersed pollen finds its way to female catkins, which start to turn green, ripening around October. Alder cones can be collected before they open and placed in a bag at room temperature to dry. The cone will release the winged seeds and these can be sown (covered with a thin layer of sharp sand) and left to over winter. They should germinate the following spring.
Hazel produces male catkins the previous autumn. These catkins shed their pollen in spring, which in turn, pollinates female catkins produced on other Hazel trees. Nuts begin life pale green and turn caramel brown as they ripen in the autumn. Up to four nuts are produced on each stalk. Hazel nuts are a favoured food of dormice but are also eaten by squirrels, mice and jays. The nuts should be picked when they start to turn brown and then sown immediately in a pot or seedbed.
This leads me on to coppicing as some of the tree species mentioned, namely Alder, Willow and Hazel can be coppiced.
Coppicing is the practice of cutting trees to ground level. Cutting an established tree down to its base instigates the fresh growth of many smaller shoots and opens up the woodland for other plant species to grow. In fact, if space is restricted, coppicing native shrubs and trees allows you to grow a greater range of species than there would normally be room for. To start a coppice, you plant bare root whips at 1.5 to 2.5m spacings. These whips can be grown in a tree nursery like the one we will be working on in West Wittering.
There are many uses of wood from a coppice, for example, hazel hurdles, gate hurdles, hedging stakes and oak bark for tanning
The reserve at West Dean Woods is a great example of how woodlands were managed in the past. The hazel, sitting amongst the oak standards, has been coppiced here for hundreds of years and is referred to as coppice or copse in 17th century maps.
Read Alex’s previous A-Z post, here.
Post by Alex Ainge