In October’s ‘A Second Spring’ we revelled in the brilliant autumn display produced by our deciduous collection. Now winter is finally upon us it seems appropriate to ask why, when some trees stand bare and still against the sky, others remain as brilliant in leaf as on a spring or summers day.
The ubiquitous nature of evergreens is hard to avoid. Historically much symbolism has been attached to the permanence of their character. Evergreens represent everything from the endurance of nature to good health in different cultures and societies. Indeed, so much comfort do we derive from their presence that millions of evergreens are brought into our homes every December for Christmas. But why do our Christmas trees continue to bristle with spiky green needles despite the winter weather?
The answer is complex. Conifers emerged over 270 million years ago and their morphological properties occur as a result of certain evolutionary processes. Europe’s most popular Christmas tree the Norway spruce, or Picea abies, has long, fine quadrangular needles. These uniformly green needles are really clever adaptations; they are actually just very tightly rolled modified leaves. The Norway spruce grows naturally in conditions which are very cold, windy and dry during the winter months. Instead of dropping its leaves and entering dormancy in response, it has developed tough leathery needles which are covered in wax and still able to photosynthesise even in the harshest of environments. Subsequently, the Norway spruce is able to make food for itself all year round, which is a big advantage in Northern climates, where the more productive warmer seasons are short and sweet.
“If you are planning on using a live Christmas tree this year remember to treat it as you would any other plant; sudden changes in temperature or environment will likely shock your tree. Introduce it to the house gradually and position it in a cool airy spot away from any radiators” Stephen Haines, Head Gardener, Winterbourne House and Garden
Not all conifers are adapted to maintain growth through freezing temperatures. Some like the Monkey puzzle tree, or Araucaria araucana, have the opposite problem. The Monkey puzzle tree is native to Chile and Argentina where temperatures reach heights a humble Norway spruce can only dream of. In fact, it gets so hot that forest fires are a common occurrence and the Monkey puzzle tree has necessarily evolved thick bark which acts as a remedial barrier. Some even grow on the slopes of volcanoes; the bark is so fire resistant that groups, or ‘islands’, of trees can often survive heavy lava flows. The Money puzzle tree once shared these rocky slopes with sharp toothed dinosaurs 200 million years ago. It’s easy to see why they developed stiff, arrow like needles which are so tough they hang around for years before they are shed.
“The seeds of the Monkey puzzle tree are delicious. You can roast them and eat them hot straight out of the oven. Thankfully they are also relatively easy to germinate. Pack them loosely in some moist perlite in a clear plastic bag and keep them warm at about 20 degrees Celsius. Check them every two days and pot those seeds developing a strong, white root, into pots with a deep, loamy compost. Patience is essential if you are planning your own Monkey puzzle harvest; they can take up to 40 years to reach a seed bearing age.” Stephen Haines, Head Gardener, Winterbourne House and Garden
The Monkey puzzle tree has been cultivated as an ornamental for a long time. So popular were they in the Victorian period that more than a century later thousands still dominate the tiny front gardens of unfortunate homeowners where Victorian “bedding” schemes once lay. In contrast, its ancient relative the Wollemi pine, or Wollemia nobilis, is the most modern of evergreen additions. The Wollemi Pine was thought to have been extinct for millions of years until it was rediscovered by an abseiling Australian park ranger, David Noble, in a canyon just north west of Sydney in 1994. Intrigued by its Jurassic looking foliage Noble retrieved a sample for further investigation.
Colleagues who suggested it may be a fern were amazed when he told them what he had seen was a great big tree with bubbling bark on trunks tens of metres high. Researchers at the Royal Botanic Gardens, Sydney, confirmed that it was indeed a new species and conservation efforts have established a wild population of around 100 trees. The Wollemi pine has had to endure much in its long existence including its fair share of ice ages. As a consequence, in winter the Wollemi Pine develops ‘polar caps’; small, white, waxy caps at the end of branches which protect tender growing tips from severe temperatures.
“Wollemi pines are so used to having big boulders tumble down upon their heads that they often naturally grow multiple stems as a defence. This means that they make an excellent specimen for the smaller garden; forming a dense, bushy plant. Plant in part shade and give it a little shelter from the wind where possible.” Stephen Haines, Head Gardener, Winterbourne House and Garden
The tiny wild population of Wollemi pines is extremely vulnerable. Disease or vandalism could cause irreversible damage. In response horticulturalists have conducted an extensive ex situ conservation effort, distributing thousands of propagated specimens around the world. So successful has this proliferation been that authorities in Australia even now encourage people to bring a potted Wollemi pine inside for Christmas. Click here if you want to find out how we are planning to celebrate Christmas this year here at Winterbourne.
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