Have you ever wondered what causes the dark vertical stripes on the cliffs around Clarens and elsewhere?

These are the result of humic acids leaching down from the overlying vegetation, combining with lichens and even bagworms.

Rodney Moffett sharing

SOME OF THE MORE INTERESTING PLANTS IN THE CLARENS VILLAGE CONSERVANCY. No. 2

LICHENS

Although not strictly speaking plants, I include them in this series as they are such fascinating organisms. A lichen is made up of two different organisms, growing in the same body and dependent on each other. The larger and visible part is a fungus, within which are hidden blue-green algal cells. The fungi serve as the attachment to a surface as well as the recipient for moisture, whereas the algae, being green, manufacture the necessary food for the body by means of photosynthesis.

Lichens are believed to cover 6% of the earth’s surface and are found on a variety of surfaces, notably tree bark, cliff faces, boulders and soil.

Three main types are recognized, viz.,

Fruticose (“Old Man’s Beard” of forests), Foliose and Crustose, of which the last two occur in the conservancy.

Foliose lichens – (Parmelia sp.)

Thin parchment-like grey bodies found on older bark and on rock surfaces.
Growth is slow and the bodies expand by 2-3 mm a year.

Crustose lichens

These lichens form crusts on porous substrates such as sandstone and make a colourful display on older rocks in the conservancy. The different species are recognized by their chemistry, resulting in the fungal component having a distinctive colour. The sandstone slab alongside, seen on the Kloof walk, has three different species on it:

  • Yellow (Acarospora sp.);
  • Orange (Caloplaca sp.) and
  • Grey (Lecidea sp.).

Through chemical action they contribute to the weathering of the rocks, and a recent study in Golden Gate Highlands National Park has estimated that lichens contribute up to 5 tons of sand per year. Crustose lichens often inhabit grave headstones made of sandstone, and because the age of these headstones is known, the rate of weathering can be measured.

The lichens in the dark cliff stripes are a special crustose type known as endolithic (under the rock) lichens and occur between the grains just below the surface, with only their fruiting bodies reaching the surface, providing food for bagworms.

Article: SOME OF THE MORE INTERESTING PLANTS IN THE CLARENS VILLAGE CONSERVANCY. No. 2

Author: Rodney Moffett

23 August 2018.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Vertical dark staining on Clarens sandstone.

Parmelia sp on a stone pillar along the Spruit Walk.

This sandstone slab, seen on the Kloof walk, has three different species on it.

Forest Elephant’s Foot and Elephant’s Root.

Rodney Moffett (Research associate, Dept. of Plant Sciences, UFS) contributing with a series of articles regarding the more interesting plants in the Clarens Village Conservancy.

Scientific names

In this series there will be the inevitable use of scientific names so a brief explanation is called for.

All living things have a scientific name known as a binomial, e.g. Homo sapiens, the name for humans. Homo (human) is the genus name and sapiens (wisdom), the specific epithet, the two making up the species name. All scientific names are in Latin and are universal, i.e. the same in any language. As any organism can have only one name, it makes for consistency, unlike common or vernacular names, whereby the same organism may have many names.

 

I begin the series with a look at two plants with an elephant connection, viz. Forest Elephant’s Foot and Elephant’s Root.

Forest Elephant’s Foot, also known as Wild Yam, Olifantsvoet & Wildeknol in Afrikaans and Ingwevu & Ufudu in isiZulu. There is no recorded name for it in Sesotho.

Its scientific name is Dioscorea sylvatica, the genus name honouring Dioscorides the Greek physician, whose Materia Medica was the leading source of the use of medicinal plants throughout the Middle Ages. The specific epithet means “of the forest”.

The leaves are shiny, dark green and heart-shaped and the flowers are small, yellowish-green, in hanging spikes. The common name refers to the large tuber (root) with corky protruberances, which in older specimens supposedly resembles the foot of an elephant. In the CVC these tubers are underground.

The tuber contains diosgenin which is or was used to prepare cortisone, perhaps explaining why it is used by the Zulu people for treating cuts, wounds, blood problems and chest complaints.

Elephant’s root, also known as Baswortel & Olifantswortel in Afrikaans and Ugweje & Umdabu in isiZulu. The Basotho appear not to use it and have no name for it.

The species name, Elephantorrhiza elephantina, is derived from the large subterranean rhizome (rhiza = root), which resembles an elephant’s trunk.

This is a dwarf shrub whose main biomass is underground in the form of a long woody rhizome. The leaves are divided and up to 1 m tall and the creamy/yellow flowers are borne in spikes at the base of the plant.

It is not plentiful but may be seen in the higher grassland parts of the conservancy. The Zulu roast the beans as a substitute for coffee and also use the plant medicinally.

Sources: Pooley, Elsa. 1998. Field Guide to Wild Flowers of Kwazulu-Natal; Pooley, Elsa. 2003. Mountain Flowers.

The Forest Elephant’s Foot is a deciduous, slender climber occurring in scrub forest and in the CVC may reach up to 4m high.

Image: Wim Wybenga

Being a legume, the Elephant’s root bears fruit which are flattened brown pods.

Image: R O Moffett