Life history of a Scots pine tree

The Scots pine (Pinus sylvestris) is one of three conifers native to Britain – the others are juniper and yew.  When mature it can be an imposing forest tree – forming the canopy of the Caledonian forest and many a commercial plantation – but when growing solitary on a windy hillside can develop fantastic twisting, gnarly forms.  The tallest known specimen in Britain stands at more than 130ft and grows on the Cragside estate in Northumberland.  The trees have distinctive feathery pairs of needles, a clouded crown and orangey, deeply fissured bark.  The wood, with its pinky tinge and open grain, makes good-quality boards but has poor durability when exposed to the weather.

Scots pines are gregarious – that is, they like to be with their own kind – and for two good reasons: first, because they pollenate each other’s flowers; second, because they promote the subsoil growth of delicate strands of mycorrhizal fungi, which exchange sugars and minerals with their roots and connect communities of the trees below ground. Scots pines grow from a tiny seed, just a couple of millimetres long, contained in a very thin, translucent ‘wing’ – more delicate than the much larger, heavier ‘helicopter’ seeds of the maples.  The seeds are hidden inside the pale brown, knobbly cones that open out in spring warmth; the seeds either drop out and spread on the wind or are extracted by birds such as tree creepers, or native red squirrels, who chew the cones open and leave the remnants lying beneath the tree.

The cones develop the previous spring; and it’s fascinating to watch the process of cone formation close-to – much easier in a young plantation than high up in the crown of a mature tree.  The male flowers come out first, growing on the lower branches out of modified shoot tips.  They look almost like pyramidal, upside -down green blackberries.  They start producing pollen in early spring, before the female flowers on the same tree have come out and increasing the chances that a tree won’t pollenate itself.  The females flowers also sprout from the tips of new shoots but are much smaller, dark red in colour and looking like tiny raspberries on stalks.  As they are pollenated the stem bends over, getting out of the way of developing shoots and hanging down.  By late spring they look like fully-developed cones, pale green in colour.  So on one tree you might see male and female flowers, new cones and last year’s open cones, all at the same time (in May, where I live in County Durham).

In Thistle Wood plantation I planted the first Scots pines about nine years ago.  The best of these is now about 15 ft tall and has been producing cones for a couple of years now.  This spring I collected about 20 cones, leaving some for the wind and birds.  I took them home in late April while they were still mostly unopened; let them open on a sunny windowsill, and then shook the seeds out – a few hundred of them.  I’ve kept a couple of hundred for sowing next year, but I propagated about 150 in a polythene bag with a little damp soil and sharp sand in it, hanging in my greenhouse.  They sprouted within a couple of weeks, and I’ve got 120 or so of them now successfully growing in small cells filled with compost.  They should be ready to plant out next year; but I still marvel at the idea of the tiny seeds and delicate seedlings, containing all the genetic information to grow into a towering, elegant tree of a 100 feet tall or more.  It’s an awesome tree with marvellous biology.

Scots pine seedling, first year
Scots pine seedling, first year

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