|ID||Michel: 246-249 Scott: 231-234. Stanley Gibbons: 245-248 Yvert: 246-249 UPU: N/A Category: pF|
|Stamps in set||4|
|Value|| 18c Ginkgo koningensis
30c Pseudoctenis spatulafa
40c Rlssikia media
50c Taeniopteris anavolans
|Size (width x height)|
|Perforation||14.25 x 14|
The genus Ginkgo was first described by the Swedish botanist Linnaeus in 1771. He is justly considered to be the father of modern biological classification and it was he who introduced the system of naming plants by genus and species that it is used throughout the world today. There is only one species of Ginkgo, namely G. biloba, that still exists today. It is indigenous only to a small area in China, but specimens are now growing in many botanical gardens and elsewhere. There are many fossil species belonging to the genus and these have been collected all over the world. The species from the 200 million year old Molteno Formation in Transkei illustrated here is one of the very earliest.
This fossil belongs to the cycads, an order of plants represented by five genera and twenty species in the Molteno Formation. Several of these species occur in the western uplands of Transkei. Pseudoctenis spatulata probably looked like the modern cycads (Encephalarfos) growing in Southern Africa today. In size, however, it was probably like a bonsai version of the living cycads. P. spatulaia and the other cycads probably grew everywhere among the undergrowth of the riverine forest belts.
The conifers, represented today in Transkei only by the yellow-wood (Podocarpus) which is confined to patches of wet montane forest, were rather more common in the region 200 million years ago. Two genera and three species, including Rissikia media, flourished on those ancient Molteno plains. Although only known from detached leaves and similarly isolated male andfemale cones, this conifer species is assumed to have been a tree of reasonable size. It occurred as a widespread member of relatively diverse deciduous woodlands.
In addition to the ginkgos, cycads, conifers and a prominent class of extinct plants known as the seed ferns, a number of genera (e.g. Taeniopteris) occurred which are known only from their leaves and cannot be reliably classified in one of the well-established orders of gymnosperms. Taeniopteris anavolans, although a rare element of that early Transkei vegetation, produced some of its most conspicuous foliage. The role that this species with its large strap-shaped leaves played in the ecology cannot be established today. lt may have occurred in open bush or dense forest, but it is easiest to imagine it as a leafy shrub in the shady undergrowth of riverine forests.
Text: Dr J.M. Anderson, National Botanical institute LexlinesRelated stamps:
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Latest update 14.12.2017
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