Signs of Spring
The first trees in De Waal Park to give an indication that spring is on the way already start sprouting fresh green leaves early in August. Invariably it is the English oak (Quercus robur) and the white ash (Fraxinus americana) that are the first to announce spring.
Quercus robur (English oak, Europese eik)
To most South Africans, the name oak (akkerboom) is synonymous with Quercus robur, the English or common oak. It is the most common oak species in this country and there are numerous trees in De Waal Park.
Q. robur is indigenous to Europe, the Caucasus, Asia Minor and North Africa. Its name is an indication of its robust and strong nature and its wood was used for building ships for many centuries. Q. robur was introduced to the Cape in the late 17th century by the Dutch. In the mild climate of the Cape the trees are infected by a fungus – leaves shrivel and die and the wood becomes rotten and stems hollow, with the result that branches break off and whole trees are uprooted during storms.
Q. robur is easily identified by its brilliant green leaves in spring that become darker during summer. They are attached to the branches at the base, with almost no stalk. In contrast, the acorns can be found at the end of long stalks known as peduncles and this species is also known as the pedunculate oak.
The acorns can be used to feed pigs. In De Waal Park they are highly prized by the grey squirrels which also bite off the young green shoots early in spring.
Quercus robur acorns
Fraxinus americana (White ash, American ash, Amerikaanse essehout)
As the name indicates this ash species is native to North America, and specifically to the north-eastern parts of the United States and Canada. It is a fast growing deciduous tree that reaches about 30 metres in height, with a straight trunk and rounded crown when mature. The bark is dark grey with a diamond-shaped pattern. The leaves occur in opposite pairs and each leaf is in turn divided into seven or nine leaflets. Leaves usually appear white beneath due to a waxy coating – hence the name white ash.
The wood is used mainly for baseball bats, tool handles and furniture. F. americana is also very popular as an ornamental parkland tree because of its attractive autumn foliage, and there are different cultivars to choose from.
Since the 1990s ash trees in America have come under attack from a green beetle native to Asia. The emerald ash borer attacks all ash species and has become highly invasive and destructive. Tens of millions of ash trees have already died as a result on that continent.
Fraxinus americana leaves