ABSTRACT On the basisl of herbarium, living and pickled material the morphology and systematics of Psilocaulon N. E. Brown sensu Ihlenfeldt ~ Bittrich is investigated. Thirteen species {including one insufficiently known species) are recognized: ' P. articulatum, PI· bicorne, P. coriarium, P. dimorphum, P. dinteri, P. foliosum, P. gessertianum, P. granulicaule, P. junceum, P. leptafthron, P. parviflorum, P. sal.icornioides, P. subnodosum. Species of Mesembryanthemum, Prenia, Brownanthus, ...
ABSTRACT Some of the physiological and ultrastructural changes occurring during the dehydration and rehydration of the "resurrection" plant Myrothamnus flabellifolia were investigated. The changes in stem and leaf orientation through angles greater than 45 degrees were recorded, and these changes, along with the change in adaxial leaf surface pigmentation, may serve to limit bright-light and/or thermal damage to these plants. M flabellifolia retained more than 70% total chlorophyll content...
The Effect of Smoke Treatment on the Germination on Four Species of Mesembryanthemum :Some Preliminary Observations
ABSTRACT The seaweeds of the Namibian coast have received little attention from researchers despite the fact that there is a successful industry based on seaweed exploitation. Beach cast Graci/aria verrucosa (Hudson) Papenfuss is collected (9000-15000 t (wet) y-1) in the Luderitz area for the production of agar, Laminaria schinzii Foslie was harvested for a short period from April 1987 to March 1989 and there is an increasing interest in utilizing other seaweed species on the coast. The natu...
ABSTRACT The poor response of some plant species, e.g. wheat, to ammonium nutrition has been attributed to a diversion of carbon allocation from structural material for root extension to functions associated with the assimilation and translocation of ammonium in the root. The aim of this research was to investigate carbon allocation in response to ammonium or nitrate nutrition in wheat, an ammonium intolerant species, and maize, which exhibits ammonium tolerance. Experiments were · carried ...
Abstract The seed that eventually gave birth to this thesis was planted in August, 1975 when, during a cruise of the Research Vessel Meiring Naude the existence of deep-sea cyclonic vortices in the South Western Indian Ocean was discovered. Little was it realised during that small, fortuitous beginning in 1975 that the study would develop into the first detailed physical oceanographic investigation of the Mozambique Ridge and adjacent Mozambique Basin areas. It could also not be foreseen tha...
Abstract. A brief review of the literature on the effects of nitrate and ammonium nitrogen sources on plant growth, and the assimilation of those nitrogen sources, has been presented. A water culture technique for the growth of maize was developed. The use of a gravel rooting medium with nutrients recycling through the rooting medium, and an iron supplement in the form of ferric citrate, resulted in superior growth of nitrate-fed plants in comparison to that observed with a hydroponic growth...
Abstract Seagrass meadows have important ecological roles in coastal ecosystems and provide high-value ecosystems services compared to other marine and terrestrial habitats. Despite this, there is growing evidence that this key ecosystems is declining on a global scale. Much of these declines have been attributed to the effects of human alterations of marine habitats. Continued destructive activities, in both South Africa and elsewhere, if not managed properly will result in the demise of sea...