Next Month: Poplar Trees by Henk Egberink
Every month (updated on 25th of the month) we will feature a tree or plant that is growing in Wynberg Park and over a period this will become a valuable resource. I express my gratitude for the enthusiastic response of those who have already undertaken to contribute to this feature of our website including the former Chairperson of Friends of Wynberg Park Henk Egberink as well as our current committee member Evelyn Holtzhauzen.
June 2018 : Blue Gums
(Thanks to Evelyn Holtzhauzen)
What’s the buzz? Why we need to value our Blue Gums in Wynberg Park
It’s virtually impossible to drive anywhere in South Africa without seeing a group of “blue gum” trees (Eucalyptus globulus,) clustered together in the landscape- many apparently planted by the early settlers – for firewood, as wind breakers and for a number of other reasons – as they trekked inland from the Cape.
In fact, these Australian evergreens are so “at home” here that is hard to imagine them as “alien” at all. There are some magnificent Blue Gums in Wynberg Park- with particularly proud trees close to the ring road as you drive down to the lower parking area. The good news for these water thirsty aliens is that they have recently been reassessed for the critical role they play in food production.
According to the SA National Biodiversity Institute (Sanbi) gum trees provide nectar and pollen for swarms of bees – and bees, in turn, pollinate about 50 food crops in South Africa- and pollinate fynbos. According to researchers the “service” provided by bees has been estimated to be worth in excess of R10.3 billion a year. This has lead to a reprieve for the trees by the Department of Environmental Affairs’ which does not require all blue gums to be felled. Only Blue Gums growing in streams, in protected areas such as nature reserves and in ecosystems identified for conservation purposes, should be felled.
This, of course, is good news for Wynberg Park- the more bees the better for the future of the fynbos.
Some additional comment from Henk Egberink
Evelyn refers to the benefits of the gum pollen to bees. The underlying reason for this is that the pollen has a very high protein content. This becomes important in the mono agricultural environment of the modern world, where the bees need a periodic boost. Hence gums are good between crop fields.
Gums are renowned for being water guzzlers and have been used for draining swamps. This is true when they are young and growing – like all young trees – but once they mature, their water usage for photosynthesis declines. Being large trees they will transpire more than the smaller trees, such as the indigenous/endemic. In drought periods their leaf stomata can be closed to conserve water, but over long periods this can cause dieback resulting in branches breaking off. I have 20 gum trees along the boundary in our complex and have lush vegetation nestling among the trees with an adjoining lush grass patch. I tend to think that with their high water retention gums improve the soil stability and conditioning. As the article indicates gums have benefits in the right environment. I can confirm that. (Useful link)
PS: why not crush a few Blue Gum leaves in the palm of your hand as you stroll through the park – and enjoy the heady aroma of eucalyptus oil – an essential ingredient of many massage oils used in health spas.
May 2018 : Silver Trees
(Thanks to Evelyn Holtzhauzen)
Silver trees are Proteas classified in the genus ( class) Leucadendron in the protea family. There are 83 species, most of which occur in the Western and Eastern Cape with a few outliers in KwaZulu-Natal – and we have them in Wynberg Park
The name Leucadendron is from the Greek, leukos, meaning white, and dendron, tree. This genus is named after and based on the silver tree, from its common name witteboom, meaning white tree, as it was known in the 1690s when the genus was first named. The species name argenteum is Latin and means silver, silvery or ornamented with silver, referring to its striking silver foliage.
Silver Trees are known as conebushes because the female flower heads form woody cones in which the fruits are borne. The species is in danger of going extinct in the wild in the next 50 years if we don’t take care of the remaining wild populations.
The characteristic silver sheen of the leaves is caused by the hairs. The intensity of the sheen varies with the weather. They are at their most silver in hot, dry weather, when the hairs lie flat to protect the leaves from drying out. In wet weather, they are not quite as dazzling, as the hairs stand more erect to allow for free air circulation.
Like all leucadendrons, it is dioecious, meaning that the male and female flowers are borne on separate plants. The flowers are in dense heads at the branch tips. The leaves that surround the flower heads, known as the involucral leaves, do not change colour while the tree is in flower, but they open wider, thus catching the light at a different angle and shining brighter silver than the rest of the leaves.
It is estimated that Leucadendron argenteum has lost 74% of its population and 55% of its habitat has been transformed primarily by urbanization and agriculture. Silver trees thrive on the forest margin where fires are infrequent, but it is also thought that the fire-exclusion management of land that contains natural populations has caused these populations to become moribund with mostly older trees and few saplings and overall fewer individuals over time.
The silver tree was of great importance for firewood on the Cape Peninsula in the 17th and 18th centuries, during which time it was extensively planted and harvested for firewood. Today it is a protected species.
The threats that Silver Trees face today are urbanization, timber plantations, the transformation of its habitat from fynbos to forest due to fire exclusion, fragmentation of the remaining populations, invasion of its habitat by alien plants, predation of its seed bank by alien squirrels, too-frequent fires, and the root rot fungus Phytophthora.
The Silver tree has inspired a few place names over the years, the earliest recorded being Witteboomen in 1672, a thicket on the way to Hout Bay. Wittebome Station in Wynberg reminds us of the days when Wynberg was a village surrounded by large groves of the silver tree. Farms on the Peninsula called Witteboom or Silverhurst were named for this tree.
* compiled with acknowledgement to SANBI-PlantZafrica
Our first featured tree / plant will be Silvertree (Leucodendron argenteum), which were once so prevalent in the area. Loss of habitat has decimated the numbers of this prominent and attractive tree but they are growing well in Wynberg Park and there are a number of saplings.