Meet the Trees in Namibian road reserves

Both the Seringa and the Pepper tree at this lay-by 28 km south of Otavi along the B1 are exotic species, which are extremely resistant to drought and frost and may thus become naturalised in areas of fairly high rainfall. Having numerous defences against insects and plant pathogens and also proliferating by root suckers, the Seringa in particular can become highly invasive, thus decreasing native biodiversity. However, in the drier parts of Namibia the danger of these two species becoming invasive is insignificant, while they provide very welcome beauty and shadeThe Seringa (Mahogany family - Meliaceae)The seringa, also known as Cape lilac or Persian lilac, is most conspicuous in spring when covered in dense panicles of pale lilac flowers, each with a dark purple centre. Their sweet fragrance is typical of spring in urban Namibia. The glossy, dark-green compound leaves usually only appear once the tree is already in flower. The yellowish appearance of the trees on the photo is due to the clusters of yellow globose fruit which mature in autumn and early winter and persist after the leaves fall. Seringas usually have a flat to rounded crown. Under favourable conditions they can reach the height of a double storied building. As a rule the tree is single-stemmed but may have several stems due to having been damaged at a young age. The attractive dark bark forms a lovely contrast to the flowering crown. Before shedding their foliage in autumn, seringas turn a beautiful bright yellow.

Seedlings will come up in any regularly watered flowerbed. They transplant easily and grow very fast. The leaves, coarsely and irregularly toothed and unpleasantly scented when bruised, as well as the bark, flowers and especially the ripe fruit are poisonous. It seems that the degree of toxicity of the fruit may vary between different trees. Children are sometimes poisoned, but can be treated successfully, unless too many of these berries have been swallowed. Nevertheless, deaths of children, poultry and stock have been reported. Despite their alluring scent, Seringa flowers seem to be unattractive to bees and butterflies but are reportedly visited by some humming birds. Apparently the grey lourie or go-away-bird can eat these berries with impunity for it can often be seen and heard in these trees in the winter months. Also African grey parrots have been seen to gnaw away at the thin layer of flesh surrounding the pip with no ill effect. The ribbed stones of the fruit, measuring about 15 mm in diameter, are often stained and used to make attractive necklaces.

My neighbour observed in his garden in Windhoek that the very common mistletoe (Tapinanthus oleifolius), identifiable by red somewhat match-like flowers and fairly large blue-green leaves, will not thrive on a Seringa, while it does very well on Pepper trees and some acacias. He even repeatedly tried to grow the sticky red seeds of this parasite on the Seringa, but heir rootlets died off after a few days after sprouting, confirming the above statement about the numerous defences this tree has.
The seringa belongs to the Mahogany family and it is thus little wonder that its pale brown wood can be used for furniture and panelling, even though quite soft. According to the Internet the timber of this tree in its native Asian distribution areas is under-utilised even though common and resistant to insect infestation. The wood is also used as firewood.
A watery decoction of the leaves can be sprayed on vegetables and fruit trees to deter leaf-eating insect, locusts in particular. Leaf litter of these trees can increase nitrogen levels in soil and increase its Ph.
The seringa is found in many gardens and farm gardens, especially in areas prone to heavy frost. Its Afrikaans name is "maksering" and in German it is known as "Fliederbaum" or "Kapflieder".
The Pepper Tree (Mango-family - Anacardiaceae)As is apparent from the photo, both foliage and branches of pepper tree on the right have a graceful drooping habit. It is a medium to large evergreen tree with strong spreading branches and rough bark. The compound leaves are greyish to light green and shiny. They consist of up to 18 pairs of narrow leaflets plus a terminal one. When crushed they give off a pleasantly resinous fragrance. The small creamy-white flowers appear in spring to summer in drooping panicles, male and female flowers growing on different plants. The fruit is a globose dry pinkish red drupe containing one seed. The red berries can be used as pepper and in fact are contained in the packets of mixed peppercorns available in supermarkets. However, not too many of these red berries should be consumed at a time.
Being exceptionally hardy, the pepper tree is planted in areas where few other trees will grow. It is found in many urban and farm gardens due to its graceful appearance and its hardiness. The flowers provide nectar, but the tree may become invasive in certain habitats.
According to Wikipedia the Pepper Tree has antibacterial properties and in its native distribution area it is used in treating wounds and infections. It has also been used as an anti-depressant, against toothache, as a diuretic, for menstrual disorders and rheumatism. Recent studies provide some support for the anti-depressant effect. Its insecticidal qualities may make it useful as an alternative to chemical insecticides. The Inca of Peru carefully rubbed the berries to remove the dry red outer skin which was then soaked in water for a few days to produce a refreshing and wholesome drink. Archaeological evidence shows that the fruits of this Pepper tree were used extensively as early as 550 - 1000 AD to produce a fermented alcoholic beverage.
Similar fruit are borne by the Brazilian pepper tree (Schiunus terebinthifolius), also found in Namibia quite frequently, which is not quite as hardy as the former. It has dark green and much wider leaves and an altogether more upright habit.
The Afrikaans and German names are "Peperboom" and "Pfefferbaum"
respectively.
Both the Seringa and the Pepper tree have a highly invasive root system and no other plants will grow in their vicinity. An indigenous tree, which is not invasive but similarly hardy, graceful and shady is the Wild ebony tree (Euclea pseudebenus) Ger. Namibischer Ebenholzbaum; Afr. abikwa, swartebbe; Herero: omuzema, N/D: tsabi.