Showing papers in "Bothalia in 1983"
TL;DR: An a priori system is presented for the broad structural classification of vegetation to provide a descriptive, consistent, easily applied system, with unambiguous, straight-forward terminology, which can be used in the field and with remote sensing and air photo techniques to convey the essential physiognomy and structure of the vegetation.
Abstract: An a priori system is presented for the broad structural classification of vegetation. The objectives are to provide a descriptive, consistent, easily applied system, with unambiguous, straight-forward terminology, which can be used in the field and with remote sensing and air photo techniques, and which can be used in conjuction with floristic and habitat terms to convey the essential physiognomy and structure of the vegetation. The attributes used are a primary set of four growth forms, a set of four projected crown cover classes, and a set of four height classes for each growth form. In addition, shrub substratum is used to define thicket and bushland. Special growth forms, substrata!, leaf and other attributes can be readily incorporated to extend the two-way table system where such detail is needed.
215 citations
TL;DR: Land units for the 900 km- Hluhluwe-Corridor-Umfolozi Game Reserve Complex in north eastern Natal were identified on aerial photographs and the physiognomy, dominants and description of the woody vegetation for each unit were identified during ground inspections.
Abstract: Land units for the 900 km- Hluhluwe-Corridor-Umfolozi Game Reserve Complex in north eastern Natal were identified on aerial photographs. The physiognomy, dominants and description of the woody vegetation for each unit were identified during ground inspections and. where necessary, the point-centred quarter method was applied. Two forest, two riverine forest, ten woodland and two thicket communities were recognized. These communities are described according to their distribution, height and percentage frequency of the components in the different canopy strata. A map at a scale of 1:25 000 was also compiled. Some of these communities are compared with other similar woodlands previously described for Natal. In some communities the frequency of certain dominant canopy species in the under tree strata was extremely low and autecological research has been suggested.
117 citations
TL;DR: The Cape Flora, one of the six floral kingdoms recognized by phytogeographers, is remarkable for its species richness and high degree of endemism, but no overall statistics are as yet available.
Abstract: The Cape Flora, one of the six floral kingdoms recognized by phytogeographers, is remarkable for its species richness and high degree of endemism, but no overall statistics are as yet available. Several long-term projects have recently been started to enumerate all the species and to record their distribution patterns. The latter aspect has been completed for 1 936 species from the three most characteristic families, i.e. Restionaceae. Ericaceae and Proteaceae, the endemic families and some of the largest genera, i. e. Aspalathus and Muraltia. Computer analysis of the distribution patterns is being undertaken and the species concentrations and centres of endemism are being calculated. The concentration of species in the mountains of the south-western Cape is confirmed and the grid square 3418 BB is found to be the richest. For the groups dealt with, the degree of endemism was found to be as high as 98%. The phytogeographical centres so far outlined agree with those of Weimarck.
82 citations
TL;DR: The most detailed information has been obtained from variations in the oxygen-18 content of foraminifera from ocean floor cores, the analysis of which has produced a record of ocean temperature changes through the Quaternary and beyond as discussed by the authors.
Abstract: The stable isotopes of hydrogen, oxygen and carbon can potentially provide evidence of past climates. The most detailed information has been obtained from variations in the oxygen-18 content of foraminifera from ocean floor cores, the analysis of which has produced a record of ocean temperature changes through the Quaternary and beyond. The use of isotope analysis of continental materials to reveal climatic change is more limited, but some advances have been made in recent years. One approach has been to utilize the variations in the isotopic composition of precipitation as recorded in ancient groundwater. Thus groundwater samples from a confined aquifer on the southern Cape coast show a marked rise in temperature since the Last Glacial maximum. The temperature changes during the Upper Pleistocene and Holocene are also reflected in the oxygen-18 content of stalagmites from the Cango caves in the same region. The widespread occurrence of C4 grasses in the warmer summer rainfall areas of southern Africa provides a novel possibility of observing temporal shifts of climatic boundaries. The distinctly high carbon-13 content of C4 plants is clearly reflected in the skeletons of grazers so that faunal material from suitably situated archaeological sites can be used to observe changes in the composition of the local grass-cover. The evidence thus far accumulated suggests only minor changes since the Upper Pleistocene. The combined evidence to date indicates that temperatures and also precipitation in southern Africa have changed since the Last Glacial maximum, about 18 000 years ago, but that shifts in the boundaries of the various veld-types were probably not very extensive.
80 citations
TL;DR: Environmental data collected at 507 plots on 22 transects, and soil analytical data from 81 of these plots, have been used to describe the plant environments of the mountains in the Fynbos Biome, suggesting that the nutrient-poor/nutrient-rich distinction must be used with care in the mountains.
Abstract: Environmental data collected at 507 plots on 22 transects, and soil analytical data from 81 of these plots, have been used to describe the plant environments of the mountains in the Fynbos Biome. Two major regional gradients are recognized: a west-east gradient and a coast-interior gradient. Of particular consequence for fynbos-environment studies is the increase in the proportion of fine soil particles from west to east. At least some aspects of soil fertility also increase towards the east. The edaphic changes are paralleled by climatic changes: chiefly a decrease in the severity of summer drought towards the east. On the coast-interior gradient a major non-climatic variable in the gradient is rock cover. High rock cover is a feature of the interior ranges. Soils with organic horizons or with E horizons are a feature on the coastal mountains, but are generally lacking on the interior mountains. The other environmental gradients recognized occur on individual transects and all include edaphic variables. The rockiness-soil depth gradient, on which an increase in rockiness is associated with a decrease in soil depth and usually a decrease in clay content, tends to occur in three situations. Firstly, it is associated with local topographic variation; the shallow, rocky soils being a feature of the steeper slopes. Secondly, it is associated with the aspect gradient; the hot, dry northern aspects having shallow, rocky, less developed soils. Thirdly, it tends to be associated with the altitude-rainfall gradient: shallower soils being found at higher altitudes. It is also at higher altitudes that higher rainfall is found. Variation in oxidizable carbon is chiefly accounted for by the altitude-rainfall gradient. Whereas at a biome-wide level, aspects of soil fertility are related to soil texture, it appears that on individual transects fertility is linked to amounts of plant remains in the soil and to rainfall. Apart from these gradients, which are found on the Table Mountain quartzites, other sources of environmental variation are due to the differences between geological types. The non-quartzitic soils are generally deeper and finer-textured. It is suggested that the nutrient-poor/nutrient-rich distinction must be used with care; at least in the mountains the distinction should not automatically be substituted for the quartzitic/non-quartzitic distinction.
79 citations
TL;DR: Fossil pollen sequences from the Cape Peninsula and the Saldanha region indicate that sub tropical vegetation and climates existed in these regions during the Miocene, and may point to the extinction of some taxa by the terminal Miocene/Early Pliocene with the subsequent strong development of macchia.
Abstract: Fossil pollen sequences from the Cape Peninsula and the Saldanha region indicate that sub tropical vegetation and climates existed in these regions during the Miocene. The pollen record from the Cape Peninsula may point to the extinction of some taxa by the terminal Miocene/Early Pliocene with the subsequent strong development of macchia. This major change can probably be related to the maximum build-up of the Antarctic ice-cap in the latest Miocene and the accompanying profound palaeoceanographic changes such as the major cooling of the Benguela current with its effect on the aridification of the Namib desert, and the global glacio-eustatic sea level drop.Parallel palynological and lithological studies in the Saldanha region show that prominent Miocene vegetation shifts were linked to profound local changes in the palaeoenvironment associated with the northward migration of the Miocene Berg River. Such studies are of paramount importance for the possible assessment of the causes of changes in the palaeoenvironment and should first be carried out at many more sites over a wide region. It is to some extent premature to draw firm conclusions as to the origin and migration of some taxa in southern Africa. The record of very primitive angiosperms such as the ClavatipolleniteslAscarina complex and Winteraceae is of considerable phytogeographic interest.
61 citations
TL;DR: In this article, the utilization of wood for fuel and building timber was studied in a 13, 000 ha area of Gazankulu, near Giyani, and the average consumption of 14,9 kg per family per day was estimated.
Abstract: The utilization of wood for fuel and building timber was studied in a 13 000 ha area of Gazankulu, near Giyani. Headloads of firewood brought in by eight of the 978 families present were monitored during six periods in a year. The two most important sources of firewood are Colophospermum mopane and Combretum apiculatum . Firewood consumption is estimated at an average of 14,9 kg per family per day. The annual demand for firewood in the whole study area is, therefore, approximately 5 300 tonnes. Living-huts and storage-huts in the process of being built were examined. The mean volumes of wood in living-huts and typical storage-huts are 1,30 m3 and1,09 m3, respectively. 89 living- and 80 storage-huts were built in a year. The demand for finished timber in the study area in that year was approximately 231 tonnes. Timber use has not yet outstripped production, but it will do so soon if alternative timber sources are not provided.
55 citations
TL;DR: It is concluded that both the South American composite and the Asian tree should be declared noxious weeds throughout the Republic and that research into their biological control is urgently required.
Abstract: The results of a survey and monitoring programme conducted in the Hluhluwe-Umfolozi Game Reserve Complex in Natal are presented. The area consists of 900 km2 of savanna and forest vegetation. Twenty alien tree, shrub and creeper species currently invading indigenous vegetation within the Complex are listed. Herbaceous aliens were not surveyed. An analysis of the habitats being invaded by these alien plants is presented and it is concluded that riverine and forest-edge habitats are those most seriously threatened by alien plant infestations. The distribution, nature and history of the infestations of each species are summarized. Distribution maps given for the eight species which are currently most important in the Complex. The potential threat posed by each species is estimated and the species are ranked in order of priority for control action. The South American composite, Chromolaena ( Eupatorium ) odorata, is identified as being the alien species currently posing the greatest threat to natural vegetation in the Complex. The Asian tree, Melia azedarach, is considered the second most important alien species invading the area. It is concluded that both these species should be declared noxious weeds throughout the Republic and that research into their biological control is urgently required.
51 citations
TL;DR: The indigenous edible plants or veld foods play a significant role in the diet of the people living in the rural areas of the Transkei and can be an important and inexpensive source of macronutrients — carbohydrates, fats and protein — and also micronutrient such as minerals and vitamins.
Abstract: Despite the fact that there is a tendency to rely more and more on foods which can be purchased at stores, the indigenous edible plants or veld foods play a significant role in the diet of the people living in the rural areas of the Transkei. Although more work is required to gather and prepare veld foods, they can be an important and inexpensive source of macronutrients — carbohydrates, fats and protein — and also micronutrients such as minerals and vitamins. Some of the more commonly-used plants such as Sonchus asper, Chenopodium album, Centella coriacea, Galinsoga parviflora, Urtica urens and Solanum nigrum are discussed and nutrient composition given. The names of a few plants which should rather be avoided, are also given. Many of these edible plants are also regarded as weeds and. instead of eradicating them, their cultivation should perhaps be encouraged.
45 citations
TL;DR: In this article, the structural features of three main vegetation types found in the coastal foreland of the western Cape Province, south of the Berg River, are outlined and the most threatened type, followed by Coastal Fynbos (14%) and West Coast Strandveld (41%).
Abstract: Floristic and structural features of the three main vegetation types found in the coastal foreland of the western Cape Province, south of the Berg River, are outlined. Coastal Renosterveld. which occupies 6% of its former extent, is the most threatened type, followed by Coastal Fynbos (14%) and West Coast Strandveld (41%). Coastal Renosterveld is closely related to Mountain Fynbos vegetation found on clay-rich soils together with West Coast Strandveld inclusions in specific habitats. Coastal Renosterveld is the product of recent regular disturbance by a short interval burning regime and overgrazing.
44 citations
TL;DR: The object of this paper is to provide a unified bibliography on the subject and to review the state of knowledge of ethnobotany in southern Africa as reflected in publications, unpublished manuscripts and museum and herbarium holdings.
Abstract: Existing ethnobotanical information for southern Africa is scattered through anthropological, medical, botanical and other books and journals, making the task of getting at the information fairly difficult. The object of this paper is to provide a unified bibliography on the subject and to review the state of knowledge of ethnobotany in southern Africa as reflected in publications, unpublished manuscripts and museum and herbarium holdings. Those aspects of ethnobotany most needing attention are identified. The information is reviewed on a subject basis.
TL;DR: The distribution of the individual sections are discussed with the aid of distribution maps as mentioned in this paper, and the centre of distribution of most sections is in the south-western Cape, hut a few sections are centred in the eastern and western Cape.
Abstract: The vast majority of the approximately 2(H) species of Pelargonium oeeurs in Africa. About SO per cent of the species are endemic to the winter rainfall region of the Cape Province, and the centre of distribution lies in the south-western Cape. The distribution of the individual sections are discussed with the aid of distribution maps. The centre of distribution of most sections is in the south-western Cape, hut a few sections are centred in the eastern and western Cape. Several sections are represented by a few species in the summer rainfall region of southern Africa. As no fossils of Pelargonium are known, deductions about the origin of the genus can only be based on the present distribution of species, according to which arguments in favour of both a northern and a southern origin can he supported.
TL;DR: The co-existence of elements of southern stock and of northerly elements, presently points to the possibilities of exchange which occurred very early in the Tertiary between the Gondwanian type of floras or the less tropical types and the Laurasian floras.
Abstract: PRESENT VEGETATION AND FLORA OF NORTHERN AFRICA, THEIR MEANING IN RELATION TO THEIR ORIGIN, EVOLUTION AND MIGRATIONS OF FLORAS AND THE STRUCTURES OF PAST VEGETATION In the light of recent works and biogeographic synthesis, the Mediterranean flora appears more and more as a heterogeneous entity, reflecting, to a great extent, the palaeogeographic and palaeoclimatic history of the region. In particular, the co-existence of elements of southern stock and of northerly elements, presently points to the possibilities of exchange which occurred very early in the Tertiary between the Gondwanian type of floras or the less tropical types and the Laurasian floras.The tropical elements are numerous and can be linked to various entities according to their age; a pantropical entity comprising in particular, Tetraclinis and Warionia, but also various families, is common to all the tropical regions and, without any doubt, contemporary with the dismemberment of Gondwana; a north-tropical entity peculiarly common to California and the Mediterranean region; a palaeotropical entity strongly heterogeneous and complex. One finds there: — thermophilous sclerophyll types often linked to the African rainforest species, — old xerophilous types, distributed in South Africa and north of the Equator (randflora), — endemic taxa of high African mountains, showing affinities with Ethiopian species or of the high African mountains, — taxa more recently arrived or even common sahelian species settled during the last pluvial. The elements of extratropical stock are composed of autochthonal or Mediterraneo-Tertiary elements, and of northern elements. The Mediterraneo-Tertiary elements are the remnants of differentiated floras generally in situ on the banks of the Tethys and on the micro-plates which occur there. The role of the Iberian micro-plate is particularly important in the western Magreb. It is advisable to associate them with various species belonging to the Irano-touranian and Saharo-Arab stocks, whose settlement is often recent. An oro-Mesogean entity is particularly important and brings together the endemo-vicariant taxa generally occurring from the Atlas to the western Himalayas. The northern elements bring together a mesothermal entity, a remnant o f the pre-glacial Lauresian floras, poorly represented in north Africa, a microthermal northern entity generally comprising species recently established and a north-alpine entity contemporary with the last glaciations, extremely localized on the high Atlas mountains. Finally, the origin of the main characteristic formations of the Mediterranean stages is examined and discussed .
TL;DR: In this article, a detailed analysis of available pollen data from the vegetation of the Sahara allows one to conclude that this vegetation has gone through but few qualitative changes during the last twenty thousand years.
Abstract: LATE QUATERNARY HISTORY OF VEGETATION AND CLIMATE OF TROPICAL NORTH AFRICA The critical examination o f available pollen data from the vegetation of the Sahara allows one to conclude that this vegetation has gone through but few qualitative changes during the last twenty thousand years. In particular, one notices an extension in the Sahara of tropical Sahel taxa about the middle of Holocene. Quantitatively, some pollen and geological data converge to Show that the Saharian plains were extremely arid between about 20 000 and 15 000 years BP and that on the mountains the vegetation became very sparse. A new colonization began on the mountains about 15 000 years ago. The pollen study of Holocene sediments from the central part o f the Chad basin was done in the Tjeri station. The results of this study exhibit a major change near 7 000 years BP, characterized in the Sahel zone by a dramatic extension o f arboreal taxa until about 5 000 years BP, probably corresponding to northward extension of the sahel savanna. One important change took place also at the same time in the wet north tropical zone where, between about 7 000 and 4 000 years BP, there occurred an extension of taxa growing presently on the well-leached soils of interfluves. Such a change near 7 000 years BP also appears in the available stratigraphical, sedimentological and pedological data from tropical north Africa. One observes particularly that, between 15 000 and 7 000 years BP, the
TL;DR: In this article, Cela explique notamment the presence d'une mangrove in Libye avec Sonneratioxylon aubrevillei and en Egypte avec Nipa burtinii.
Abstract: La repartition de la flore Tertiaire en Afrique, tres differente de l’actuelle, se comprend si on tient compte de deux facteurs essentiels: la regression des mers epicontinentales vers le nord et la derive du continent africain II en resulte qu’a l'Eocene inferieur, l’equateur se trouvait a environ 1 000 km au nord de sa position actuelle Ces modifications aboutissent a des transformations importantes de l’environnement climatique et par consequent de la repartition des flores Cela explique notamment la presence d’une mangrove en Libye avec Sonneratioxylon aubrevillei et en Egypte avec Nipa burtinii La foret dense est presente dans le Paleocene du Tinrhert avec Entandrophragmoxylon normandii (comparable a l’actuel Entandrophragma angolense) Les formations de foret dense, developpees a l’Eocene, surtout sur le rivage, sont suivies plus au sud, d’une savane qui s’etend davantage a I’Oligocene et qui peut atteindre la mer Cependant, on trouve encore en bordure de mer a l’Oligocene, des especes de foret dense comme Entandrophragmoxylon magnieri (comparable a Entandrophragma candollei ) espece qui avoisine des depots deltaiques avec de grands troncs qui indiquent une flore plus seche (Detarioxylon aegyptiacum, Combretoxylon bussonii et Pterocarpoxylon tibestiense (rapproche du Pterocarpus erinaceus de savane), mais parfois accompagnee de troncs de foret-galerie ( Atherospermoxylon aegyptiacum, Monimiacee) Au Miocene, l’assechement continue et la savane progresse Les Palmiers apparaissent et des galeries forestieres subsistent, mais meme a proximite de la mer, le biotope est sec au Miocene inferieur dans le Nord de l’Afrique Ce n’est que vers le sud que la vegetation hygrophile apparait au niveau du Tibesti avec Myristicoxylon vincentii Ainsi pres de la position presente de l’Equateur, la mangrove se retrouve au Senegal dans le Paleogene du Cap-Vert avec des pollens de Rhizophoracees Sonneratiacees, Avicennia et Nipa ( Spinizonocolpites ) et la foret dense subsiste dans sa position actuelle entouree d’une savane
TL;DR: The structural changes that have occurred in the vegetation of the Hluhluwe-Umfolozi Game Reserve Complex have been quantified using 1937, 1960 and 1975 aerial photographs, and related to the management history.
Abstract: The structural changes that have occurred in the vegetation of the Hluhluwe-Umfolozi Game Reserve Complex have been quantified using 1937, 1960 and 1975 aerial photographs, and related to the management history A progressive increase in both tree and shrub cover has occurred In the short term, both intensive woody plant removal operations and controlled burning applications appear to be effective in retarding the rate of encroachment by shrubs and trees However, neither was effective in the long term Significant reductions in tall grass cover attributed to sustained overgrazing have occurred
TL;DR: Though generally Troll’s system may confirm that the inflorescences of all species investigated proved to be variations of one of the two fundamental types, it sometimes needs morphological experience to apply Troll's system to woody plants of tropical regions.
Abstract: Great diversity is found in inflorescences of angiosperms. According to Troll this is due to the variation of two types only: the polytelic and the monotelic type. In the monotelic inflorescence, the apex of the inflorescence axis commonly ends with a terminal flower. This also applies to all the floral branches below the terminal flower. All of these branches, whether branched or not, proved to be homologous elements, and they are all referred to by the term ‘paracladia’ because these branches repeat the structure of the main axis of the flowering system. Accordingly, their ramifications are called paracladia of the 2nd to nth order. Since by the presence of the paracladia the number of flowers in the flowering system is increased, they may be called ‘enriching branches’. Consequently the whole area which produces the enriching branches may be designated as an ‘enriching field’. In the lower part of the flowering shoot this zone is commonly preceded by a ‘field of inhibition’ within which the development of paracladia is inhibited more or less abruptly. The same zonation can be recognized in the individual paracladia if these are not reduced in any way. In perennials, the axillary buds at the base of the whole stem do not develop within the same season, but will give rise to the innovation shoots at the beginning of the following season. Therefore this area has to be distinguished as a ‘field of innovation’. The polytelic type of inflorescence probably has been derived repeatedly from the monotelic during the evolution of angiosperms by reduction of the terminal flower and specialization of the paracladia of the monotelic system. The distal elements are reduced to single lateral flowers or lateral cymes (partial florescences) which constitute elements of an apical system composed of lateral flowers. Instead of ending in a single flower, the floral axis thus terminates in a multi-flowered so-called polytelic ‘florescence’. The lower lateral branches repeat the structure of the main stem by producing (indefinite) florescences themselves and therefore may be termedparacladia (of the polytelic system). As in monotelic inflorescences the area of paracladia — the ‘enriching field’ — can be preceded by a ‘field of inhibition’ and, in perennial plants, by a ‘field of innovation’. Though generally we may confirm that the inflorescences of all species investigated (about 20 000 from nearly all angiosperm families) proved to be variations of one of the two fundamental types, it sometimes needs morphological experience to apply Troll’s system to woody plants of tropical regions. Difficulties may derive from prolepsis and syllepsis of the innovation shoots, prolification of the inflorescence axis and, abundantly, by the deficiency of clearly marked limits between sprouts growing in different seasons. In each of such cases, however, the homologous flower-bearing-elements can be identified by comparing their positions within the whole system of ramification.
TL;DR: In this paper, a detailed information on the colonization and succession of sand dunes, dune slacks and rocky outcrops along the coast between the Riet and Kleinemonde Rivers is provided.
Abstract: Detailed information on the colonization and succession of the sand dunes, dune slacks and rocky outcrops along the coast between the Riet and Kleinemonde Rivers is provided. The main reasons for the paucity of plants on the vast dune system are the movement of sand by wind and the inconsistent rainfall. Zonation of species along a dune transect is not particularly marked although a greater diversity of species is found in the dune slacks where an increased amount of seepage moisture occurs. Reclamation practices in blow-out areas have resulted in a pioneer cover of indigenous plants which should provide dense coastal scrub if the introduced Acacia cyclops is kept under control. Establishment of plants on the rocky promontories has occurred over a very long time and well developed communities and soils have formed. Salt spray and high winds are major controlling factors in the zonation of species along a gradient in this area.
TL;DR: In the vast region of East and southern Africa the alternating glacial and interglacial periods of the Quaternarv were characterized by considerable changes in temperature and precipitation, during the last glacial maximum the influence of the ITCZ was limited, while the circulation systems were strengthened.
Abstract: In the vast region of East and southern Africa the alternating glacial and interglacial periods of the Quaternarv were characterized by considerable changes in temperature and precipitation. During the last glacial maximum the influence of the ITCZ was limited, while the circulation systems were strengthened. The ocean surface waters were cooler and the Benguela Current was activated. In the montane areas of East Africa and also in southern Africa the temperature dropped by about 6°C. During this hypothermal period, rainfall on the east African plateau and mountains diminished. Summer precipitation could still penetrate the eastern half of southern Africa from the Indian Ocean, while the western half was arid to semi-arid. Cyclonic winter rain migrated further north beyond the latitude of the Orange River. The consequences of these climatic changes during the last glacial maximum were that the woodlands of East Africa opened up. On the plateau of South Africa austro-afroalpine vegetation dominated. The south coastal plain was very windy and cold to temperate, while the Namib and Kalahari were respectively hyper-arid and semi-humid. During hyperthermals the vegetation pattern resembled present-day conditions more closely.
TL;DR: A unique obligatory symbiosis exists between Ficus capensis Thunb.
Abstract: A unique obligatory symbiosis exists between Ficus capensis Thunb., and its pollinator, Ceratosolen capensis Grandi. Flowers from both aerial and geocarpic syconia may be pollinated and produce seeds. Females of C. capensis possess specialized mesothoracic pockets in which pollen is transferred from ripening syconia to receptive ones. A second primary sycophile, Sycophaga cyclostigma Waterston, appears to be ineffective in pollination.Several secondary sycophiles oviposit through the syconial wall. Strong sexual dimorphism exists in most sycophilous wasps. All female flowers have the potential to produce either seeds or galls and variation is merely one of gross morphology. Flowering is distinctly asynchronous. Seeds are dispersed by various fruit predators and germinate very easily under warm humid conditions.
TL;DR: The Disinae (Orchidaceae) are widespread in tropical montane Africa and the Cape temperate region, therefore showing a distribution range typical of a temperate herb in Africa, corroborated by recent studies on Cupressaceae, Pooidae and Compositae.
Abstract: The Disinae (Orchidaceae) are widespread in tropical montane Africa and the Cape temperate region, therefore showing a distribution range typical of a temperate herb in Africa. Centres of endemism and high species richness are recognized in the southern and western Cape Province, the Natal-Transvaal escarpment mountains, the watershed between the Rivers Zaire and Zambesi and the southern highlands of Tanzania, the East African highlands and Madagascar. The number of species and their degree of endemism decrease from south to north. Several regions, e.g. Zimbabwe and West Africa, are outliers of other regions, or overlap zones between regions. An attempt is made to determine the history of the group by vicariance biogeographical analysis, but the resultant area cladogram is uninformative. This may be due to the vagility of the taxa.Areas of endemism of supra-specific taxa are determined. These areas appear on recent palaeoenvironmental data to be possible refugia (Cape fold mountains, the South African Drakensberg and the East African Rift Valley mountains), from where the taxa spread when the climate ameliorated after the last glacial. This model is corroborated by recent studies on Cupressaceae, Pooidae and Compositae.
TL;DR: The evolutionary history of the genus Capsicum is now envisaged as including three distinct lines leading to the domesticated taxa, which suggests that Nigeria, Egypt, Tunisia and Ghana are the leading producers of peppers in Africa.
Abstract: The genus Capsicum (Solanaceae) includes approximately 20 wild species and 4-5 domesticated taxa commonly referred to as ‘chilies’ or ‘peppers’. The pre-Colombian distribution of the genus was New World. The evolutionary history of the genus is now envisaged as including three distinct lines leading to the domesticated taxa. The route of Capsicum to the Old World is thought to have followed three different courses. First, explorers introduced it to Europe with secondary introduction into Africa via further exploratory expeditions; second, botanical gardens played a major role in introduction; and third, introduction followed the slave trade routes. Today, pepper production in Africa is of two types, vegetable and spice. Statistical profiles on production are difficult to interpret, but the data available indicate that Nigeria, Egypt, Tunisia and Ghana are the leading producers. Production is mainly a local phenomenon and large acreage is seldom devoted to the growing of peppers. The primary peppers in Africa are C. annuum and C. frutescens.
TL;DR: Dune vegetation changes were studied qualitatively with the aid of air photos taken in 1937, 1957 and 1976 to indicate that in secondary, unafforested areas the vegetation is evolving rapidly towards a Secondary Dune Forest.
Abstract: Dune vegetation changes were studied qualitatively with the aid of air photos taken in 1937, 1957 and 1976.Results were transferred to 1:10 000 scale maps. In 1937 roughly 80% of the dune forest habitat was occupied by planted fields and post cultivation serai stages such as Secondary Grasslands and Dwarf Shrubland, Secondary Scrub and Acacia karroo Woodland. In three areas, the vegetation cover had been completely destroyed and drift sands had formed. In the 1950’s the trend of vegetation degradation was changed by the implementation of an afforestation programme by the Department of Forestry. The 1976 air photos indicate that the post cultivation serai stages of 1937 had been largely replaced by forest plantations. In secondary, unafforested areas the vegetation is evolving rapidly towards a Secondary Dune Forest.
TL;DR: In this article, an agglomerative cluster analysis and a principal components analysis of habitat, based on 27 quantitative soil variables, are compared with a Braun-Blanquet classification of the vegetation of the Manyeleti Game Reserve in the eastern Transvaal.
Abstract: An agglomerative cluster analysis and a principal components analysis of habitat, based on 27 quantitative soil variables, are compared with a Braun-Blanquet classification of the vegetation of the Manyeleti Game Reserve in the eastern Transvaal. The results indicate that these techniques can be successfully used to obtain relatively homogeneous habitat classes, characterized by sets of environmental (soil) variables and not only single variables individually, and which are furthermore significantly correlated with the recognized plant communities of the area.
TL;DR: Alloteropsis semialata (R. Br.) Hitchc.
Abstract: Alloteropsis semialata (R. Br.) Hitchc. sensu Chippindall (1955) and Clayton (in press) is the only known grass species in which elements with both non-Kranz and Kranz leaf blade anatomy, and therefore with C 3 and C 4 photosynthetic pathways are included. In the past, two taxa had been recognized, but the characters used to separate them were found to be unreliable, so they were united. However, study of voucher specimens for anatomical and physiological work has shown that C 3 and C 4 taxa may be separated on the basis of morphological characters that differ from those considered in the past. Therefore, two taxa are again recognized, this time at the rank of subspecies, and the name Alloteropsis semialata subsp. eckloniana (Nees) Gibbs Russell stat. nov . is published.
TL;DR: The morphological variation within the species suggests separation of taxa below specific level, or perhaps even at species level, but this will require more detailed information about the ecology, distribution and the cytology.
Abstract: The genus Schoenoxiphium of the tribe Cariceae of Cyperaceae is conservatively accepted as being restricted to the African continent and Madagascar. The special features of the inflorescence structure are described. The following species are provisionally recognized: S. basutorum Turrill, S. distinctum Kukkonen, S. ecklonii Nees, S. filiforme Kukenthal, S. gracile Chermezon, S. lanceum (Thunberg) Kukenthal, S. lehmannii (Nees) Steudel, S. madagascariense Chermezon, S. perdensum Kukkonen, S. rufum Nees, S. schweickerdtii Merxmiiller & Podlech, and S. sparteum (Wahlenberg) Kukenthal. A key to the species is provided and their distribution is roughly outlined. The morphological variation within the species suggests separation of taxa below specific level, or perhaps even at species level, but this will require more detailed information about the ecology, distribution and the cytology.
TL;DR: A scheme of nomenclature and coding has been proposed, which permits a more detailed and unambiguous recording of endothecial variety than was hitherto possible.
Abstract: A method has been devised for the screening of the endothecium in flowering plants, principally with a view to describing the cell wall thickening. A scheme of nomenclature and coding has been proposed, which permits a more detailed and unambiguous recording of endothecial variety than was hitherto possible. There is some evidence that this structural variation could have taxonomic and phylogenetic significance.
TL;DR: Nocturnal petal movements were recorded from 48 genera and 106 species growing in cultivation at the Royal Botanic Gardens, Kew and in the wild in Canada, Great Britain, France, Italy, Greece, Canary Islands and South Africa.
Abstract: Nocturnal petal movements were recorded from 48 genera and 106 species growing in cultivation at the Royal Botanic Gardens, Kew and in the wild in Canada, Great Britain, France, Italy, Greece, Canary Islands and South Africa. Seven different night positions of petals, as distinct from day positions, are recognized and discussed.
TL;DR: As modern groups of angiosperms have appeared over a period of more than 80 million years, the relative position of the southern continents has changed over the past 90 m.y. as discussed by the authors.
Abstract: As modern groups of angiosperms have appeared over a period of more than 80 million years, the relative position of the southern continents has changed. For the First 20 m.y. of this period, opportunities for migration were good between Africa and Europe, and this constituted the main pathway for migration between the northern and southern hemispheres. South America progressively moved away from Africa and towards North America over the past 90 m.y. Southern South America and Australasia shared a rich, warm temperate rainforest flora until about 40 m.y. ago. The development of modern climates during the past 10 m.y. has set up modern patterns of vegetation.
TL;DR: It is likely that past changes in climate can still be partly traced in the vegetational pattern, particularly in geographical anomalies, and that study of these patterns provides complementary evidence to palynological research.
Abstract: Southern Africa is characterized by a highly diversified vegetational cover with extremes as contrasting as desert, tropical forest, alpine grassland, or mediterranean type scrub, and many other types in between. This vegetational pattern is strongly correlated to the climatological pattern. It is therefore likely that past changes in climate can still be partly traced in the vegetational pattern, particularly in geographical anomalies, and that study of these patterns provides complementary evidence to palynological research. The following anomalies in the vegetational pattern are briefly discussed: 1. island-wise occurrence of Afro-montane vegetation on mesic, sheltered sites in the southern Sudano- Zambezian Region, in particular in the Highveld grassland/False Karoo transition area; 2. similar westward occurrence of Sudano-Zambezian scrub patches in the Karoo-Namib Region near the Orange/Vaal confluence; 3. scattered occurrence of Sudano-Zambezian woody species in a matrix of Karoo-Namib vegetation in the marginal Karoo-Namib Region; 4. island-wise occurrence of frost-tolerant, dry, karroid dwarf shrub vegetation of predominantly C,-plants on isolated peaks in the winter rainfall area of Namaqualand; 5. peculiar patchy distribution of some succulents in wide areas of climatically rather homogeneous, succulent dwarf shrub vegetation of predominantly CAM-plants in the escarpment area of Namaqualand. a pattern reminiscent of that in many Cape fynbos species. Interpretation of these patterns logically leads to the conclusion that these result from a previously wetter, a previously cooler, or a previously wetter and cooler climate, respectively, over the parts of southern Africa under discussion. This conclusion is compared with published palynological views.