In this study I documented the convergence of five congeneric bird-pollinated plants (Aloe pluridens, A. lineata var. muirii, A. speciosa, A. africana, and A. ferox) into three functional groups based on size, shape, and the arrangements of flowers on the inflorescence, but also nectar rewards, pollen deposition sites on the bird-pollinators, and the degree to which bees play a role in their pollination. Individuals of similar functional groups were divergent in their peak flowering times and limited their degree of flowering overlap further by spatial aggregation and niche separation, within the Thicket of the Gamtoos River Valley. The nectar properties were especially useful in structuring the bird pollinator community, which resulted in greater ethological isolation and hence, greater reproductive assurance in the mixed co-flowering plant communities. Choice array experiments revealed that it was the fine scale aggregation of flowering individuals that ensured that bird-pollinators feed selectively, since when equal choice was available, interspecific visitation increased significantly compared to natural scenarios. Bird behaviour and the ecological intermediateness of one to the species explained its prominence in hybrid combinations. The spatial occurrence of hybrid individuals can be traced back to the energetics of foraging and its influence on bird floral constancy. The pollination ecology of similar South African Aloe species were extrapolated from these and recent findings by various authors, but emphasises the need for a robust natural phylogeny of the Aloaceae in order to draw comprehensive conclusions on the evolutionary radiation of this highly charismatic group.

Plant ecological studies at the population level on carefully selected single species provide key insights into their structural and functional ecology, but may also be extrapolated to enhance ecologists’ understanding of other similar taxa, which ultimately contributes to the conservation and management of the group as a whole. Long-lived, slow-growing plants such as succulents and cycads, which are popular among plant collectors and often threatened as a consequence, are prime candidates for research owing to the considerable benefits to their conservation and management. Aloe plicatilis is a unique and charismatic arborescent succulent monocot that is endemic to the Cape Floristic Region, South Africa. It is restricted to mountainous areas in the Cape Winelands in the south-western Cape, and is the only tree aloe that occurs in the Cape fynbos. Aloe plicatilis is a prized species in the horticultural trade in succulent plants, and a recent spike in exports of the species from South Africa, including consignments of reportedly wild-collected plants, has raised concerns about its persistence in the wild. Potential threats to A. plicatilis combined with a dearth of knowledge on the species’ ecology prompted a broad-scale ecological study on the species, and an assessment of how potential threats may be affecting its survival in the wild. The primary aim of this study was to investigate three key elements of the ecology of A. plicatilis, viz. (1) demographic trends across the species’ distribution, (2) the reproductive ecology of the species, and (3) its fire ecology. The study was first contextualized by compiling a comprehensive review of the ecology of African aloes. The objectives specific to A. plicatilis then involved determining the species’ habitat profile, its geographical distribution, number of populations, and estimations of the sizes thereof. Further objectives entailed an assessment of the population size structure and density of a large proportion of A. plicatilis populations across the species’ distribution, studies of its pollination and seed ecology, and an investigation of the species’ fire survival and the impacts of fire on population structure. The study concludes with a synthesis that highlights and extrapolates the findings of the research and the implications these have for other Aloe species and similar long-lived, slow-growing plant taxa. Threats to the persistence of A. plicatilis in the wild are discussed, and recommendations are made for management, population monitoring and directions for future research. Several of the knowledge gaps in aloe ecology highlighted in the review were investigated for A. plicatilis in this study, notably seed ecology, resprouting and fire ecology. The demographic study on A. plicatilis uncovered 14 previously undocumented populations, bringing the total currently known to 30. Fifty percent of the 19 populations surveyed for size structure, density and spatial extent exhibited bell-shaped size class distributions (SCD), which are hypothesized to indicate an adult-persistence population survival strategy, typical of many long-lived, slow-growing plant taxa. This trend was reflected in the apparent lack of persistent seed banks in A. plicatilis, which suggests minimal ‘drib-drab’ recruitment over time as opposed to mass episodic recruitment. There appears to be a positive relationship between A. plicatilis population size and reproductive success. Quantification of natural fruit and seed set at three A. plicatilis populations revealed that large, dense populations exhibit higher seed production/plant relative to smaller and sparser ones, suggesting an Allee effect. Pollinators of the species (insects and specialist avian nectarivores) are probably attracted in greater numbers to large, dense populations where prolific food rewards and short inter-plant distances facilitate efficient floral visitation, and hence effective pollination. Recruitment in A. plicatilis appears to depend on the alignment of numerous biotic and abiotic factors such as slope, aspect, temperature, quantity and timing of rainfall, fire occurrence, and the availability of suitable rocky microsites. These sites are of particular importance as they serve as fire refugia and provide nurse objects (nurse plants and/or nurse rocks), which create cool, shady conditions, where organic matter and moisture may accumulate, all of which appear to be essential to germination and establishment in A. plicatilis. As with most plant species, the large majority of A. plicatilis seeds are dispersed close to parent plants (estimated 1.3 – 15.3m for 0.8 and 4.0m in height respectively). However, the occurrence of A. plicatilis on Paarl Mountain and the Paardeberg, which are completely isolated from other mountain ranges where the species occurs, suggests the possibility of long-distance dispersal by strong, persistent and gusty summer winds that blow during the peak seed dispersal season. Size structure analyses and detailed field observations suggest that A. plicatilis displays the ‘bonsai effect’, whereby plants growing in very rocky sites with restrictive rooting space and/or sites where they are exposed to persistent strong winds, are maintained as stunted individuals termed ‘suppressed juveniles’ or ‘reproductive dwarfs’. However, rocky sites also act as fire refugia and provide nurse rocks, both of which are necessary for recruitment and persistence. Hence, there appears to be a trade-off between plant size and fire survival probability: individuals in very rocky sites are well-protected from fire, but often remain stunted and unreproductive, while plants in less rocky sites with more rooting space can attain larger sizes but are more vulnerable to fire damage. Aloe plicatilis is unique in that it is the only Aloe species that possesses thick, corky bark, which affords it additional fire protection. Its stems, leaves and bark also contain large water reserves, which may act as a fire retardant. Fire survival is heavily reliant on the prevention of hydraulic failure by the thick insulating bark and the protection of apical meristems, which facilitates onward apical growth, since A. plicatilis is incapable of epicormic or basal resprouting post-fire. Despite the species’ fire survival adaptations, A. plicatilis population size structure may be dramatically altered by fires, especially at sites where they have been excluded for periods longer than appropriate for the vegetation type. The very recent name change from Aloe plicatilis to Kumara plicatilis has important conservation implications for the species. Recognition of the species’ uniqueness by ascribing it to a monotypic genus may result in greater conservation efforts to preserve its sole genetic lineage; nonetheless, the inadvertent and unwanted consequence may be increased perceived rarity and desirability, and concomitant threats to the species’ persistence in the wild. Illegal wild-harvesting of A. plicatilis does not appear to be posing a major threat to the species at present; however, monitoring of small and/or low-lying and easily-accessible populations is advised. The four smallest surveyed populations are also recommended for long-term monitoring due to poor or absent recent recruitment and vulnerability to climate change at the species’ distribution edge. Appropriate management actions are recommended for twelve A. plicatilis populations that are under potential threat by invasive alien plant species encroachment. The baseline data presented in this study serve as a foundation for future studies, which will build on current understanding of the ecology of A. plicatilis, other aloe species, and long-lived, slow-growing plant taxa in general. Opportunities for future research on A. plicatilis, (which also apply to other Aloe species) include: (1) a study on the long-term population dynamics of the species, which includes population modelling; (2) further studies on the species’ pollination ecology, seed dispersal and recruitment patterns; (3) investigations into the physiological role that bark properties and plant tissue water content play in fire survival and (4) a predictive species distribution modelling study that models the current distribution of A. plicatilis, and how this might change under different climate change scenarios. Modelling Cape fynbos species distributions using climate change predictions is vital for adaptation and mitigation in the south-western Cape, where severe climate change impacts are forecast. Furthermore, deepened insight into the ecology of long-lived, slow-growing and potentially threatened plant species will contribute to predicting and understanding their responses to threats including climate change, which will ultimately lead to better management and conservation practises.

Ph.D. / This chemotaxonomic study of the leaf phenolic compounds in the genus Aloe is introduced by presenting a review of Aloe taxonomy, followed by a second review of all known leaf compounds. A chemotaxonomic study of virtually all species of Aloe has made it possible to define several chemical groups in the genus of 420 species. The chemical groups are either identified by a single marker compound or by a series of unique compounds. The following groups have been identified and the chemotaxonomic value of each group is discussed: • An aloin / aloinoside / microdontin group, comprising 36 species, mostly of tropical origin. This group includes species not previously associated with one another. • An 8-O-methyl-7-hydroxyaloin group. Here the co-occurrence of some leaf compounds suggests that 8-O-methyl-7-hydroxyaloin is not homologous in the 18 species where it has been detected. Evidence is presented illustrating that 8-O-methyl-7-hydroxyaloin is an 'hybrid compound' which forms when two chemically divergent species (aloin- and homonataloincontaining parents) are crossed. • An aloenin group, comprising 16 species which are believed to be a monophyletic group. • A microstigmin group, indicating a taxonomic alliance between series Purpurascentes and series Anguialoe, with A. broomii an intermediate between the two. • A 10-hydroxyaloin B group, represented by series Asperifoliae and related species, which appears to be a drought adapted Glade of tropical origin. • A homonataloside group, comprising 14 species, suggesting a biochemical link between the aloes of north Africa and southern Africa. • An aloeresin E and F group, indicating a taxonomic alignment between series Mitriformes and five anomalous species. • A plicataloside group, with its single marker compound indicating a taxonomic relationship between 20 mostly tropical east African species. • A flavone group. The large number of species with flavones (sections Leptoaloe Graminialoe, Lomatophyllum and series Macrifoliae) are suggested to be basal in the genus. • A flavanone group. A few anomalous species produce flavanones but it is unlikely that they form a monophyletic group. A concluding review of leaf exudate compounds (not mentioned above) is also presented which includes hypotheses on the chemotaxonomic value of chromones and anthrones in general. A chemical re-arrangement of species is presented in the form of a new 'chemical classification' for Aloe based on chemotypes. These chemical groups have lead to an improved understanding of natural relationships in a genus where no satisfactory infrageneric classification has hitherto been available.

A research report submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfillment of the MSc by Coursework Degree (in Resource Conservation Biology) June 2017. South Africa. / Understanding why species occur where they do and, predicting where species might migrate to under different global change scenarios is an important aspect of biodiversity conservation. Regions that harbour high levels of species diversity and endemism arising from sharp local climatic and ecological gradients are highly susceptible to changing conditions. Kumara plicatilis is a tree aloe endemic to the Boland mountain ranges in the species-rich fynbos region in the Western Cape Province of South Africa. The species is currently listed as Least Concern as far as habitat degradation, population decline, invasive species and direct-use threats are concerned although impacts of anthropogenic climate change on this habitat specialist remain undocumented. This study used species distribution models to successfully classify the environmental niche of the species as well as delineate spatial patterns of probable occurrence and abundance based on this niche. In addition, models based on the IPCCs 2014 ‘best-case’ and ‘worst-case’ climate change scenarios provide projections of changes in the spatial occurrence patterns of Kumara plicatilis expected under conditions of shifting climates. Niche-based statistical analyses were further used to draw temporal comparisons between current and future projected ranges to ascertain the degree and properties of shared niche space now and in the future. Results indicate that suitable habitat conditions for the species distribution is irregularly spread around the central and southwestern fynbos region constrained by several climatic and biophysical variables including winter rainfall and temperature conditions as well as vegetation type. The species is expected to experience limited to severe declines in the area of suitable habitat available under mild and harsh climate change conditions, respectively. The patterns arising from these models are in line with the environmental niche measurements which show large degrees of overlap between current and future niche space of the species. These outcomes suggest that Kumara plicatilis displays traits of environmental niche conservatism where unsuitable climate and biophysical conditions can limit its geographic range and local extinction of populations can occur due to global change. Whilst the results of this study offer a useful and initial insight into the possible impacts of shifting climates on this species, outcomes from modeling should be interpreted with caution to reach the best management decisions and conservation action for this endemic species. / MT 2017

Manure production and nutrient management in pasture-based dairy production systems by Walter Svinurai The effect of dietary treatments on nutrient excretion was determined and an attempt to improving the retention of excreted nitrogen in stored manure using Aloe ferox leaf gel (AFLG) and pine bark was conducted at a pasture-based dairy farm. The animal mass-balance method was used to determine nutrient excretion by cows fed on three dietary treatments, Lolium perrene-based treatment (LP), Lolium multiforium-based treatment (LM) and Lolium perenne- Trifolium repens -based treatment (LTF). In separate experiments, slurry from dairy cows fed LM was amended with AFLG and pine bark at concentrations of 25, 50, 75 and 100 g/l and stored under anaerobic conditions for 16 days. The highest and lowest excretions of N, P and K were observed in LM and LP treatments, respectively. Increasing dietary N improved K and N retention in milk and, consequently increased milk urea nitrogen (MUN) and N excretion (P < 0.05). The concentrations of AFLG affected N and P retention in manure (P < 0.05). The highest retention in total Kjeldahl nitrogen (TKN) of the initial was 42% AFLG at 25g/l inclusion rate. Ammonium nitrogen (AMN) concentration increased significantly due to the interactive effect of AFLG inclusion rate and time. Pine bark powder significantly improved N and P retention in manure at all concentrations. The retention in TKN was higher (P < 0.05) at 25g/l pine bark powder than other concentrations. The interaction effect of inclusion rate and time increased iii AMN (P < 0.05). Dietary treatments significantly affected nutrient excretion, and AFLG and pine bark considerably improved N retention in stored slurry. Findings from the filed trial suggest the need for more attention on managing dietary nutrients in the post-rainy and cool-dry season when growth of pasture influenced choice of dietary treatments that led to high nutrient excretion. Field simulation of the additives to determine their efficacy and environmental hazards was recommended.

Thesis (M. Tech. (Biomedical Technology)) -- Central University of Technology, 2014 / The rising costs of health care, the outbreak of drug resistant organisms, health depleting lifestyles and the risky side effects of currently used drugs are world-wide problems. This has led to the search for novel drugs and drug leads. Traditional healers and other individuals across the globe possess unlimited knowledge on the healing powers of different plants that has been passed on through generations. This knowledge together with scientific investigations can lead to the eradication of most of the diseases either by treatment or prevention. Aloe ferox Mill. is one of the plants that have gained a lot of interest from the pharmaceutical industry. The plant has over 80 documented medicinal uses. These include treatment of impotence and infertility, sexually transmitted infections, arthritis, hypertension, leukaemia, bacterial and fungal infections. It is also known as a blood purifier, widely used as a laxative and anti- inflammatory agent. More research is required to discover more about A. ferox and its benefits to health as well as to investigate its potential for the development of novel drugs. The current study was focused at investigating the anti- cancer, anti- microbial antidiabetic, cytotoxic activities and phytochemical composition of leaf extracts of A. ferox. Three cancer cell lines namely: breast (MCF7), colon (HCT116) and prostate (PC3) cancer cell lines were used to investigate the anticancer activity of the extracts using the Sulforhodamine B (SRB) method. To determine the anti- diabetic activity of the plant extracts the C2C12 and Chang cell in- vitro models of glucose uptake were used. The micro- dilution technique was IV used to evaluate the antibacterial and antifungal activity of the extract. The safety of these extracts against normal human foetal lung fibroblasts (W138), Chang and C2C12 cells was done by through the SRB and the MTT methods. To determine the phytochemical profile of A. ferox the DPPH radical scavenging and the Folin Ciocalteu methods were used to test the antioxidant activity and the total phenolic content of the different extracts respectively. Different methods were used to determine the presence of phytochemicals such as steroids, saponins, alkaloids, carbohydrates and flavonoids. LCMS was also done to detect the elemental composition of the plant extracts. According to the CSIR criteria A. ferox was inactive against the cancer cell lines used. It however exhibited antioxidant activity even at low concentrations, with an EC50 of 0.865 ± 0.783. The methanol extract showed more phenolic content than the dichloromethane and aqueous extracts at a concentration of 5mg/ml. It is believed that the antioxidant activity correlates with the phenolic content and quality of the phenols present in the plant and more assays have to be done to prove this hypothesis. Other phytochemicals found in the extract included saponins, steroids, alkaloids as well as flavonoids. Both the methanol and aqueous extracts of A. ferox caused a significant increase in glucose uptake by C2C12 cells but caused a slightly decreased uptake by the Chang cells. The plant extracts inhibited the growth of Staphylococcus epidermidis, Streptococcus pneumonia, Escherichia coli and Candida albicans at a concentration of 15mg/ml extract. Candida tropicalis and Escherichia faecalis were resistant to A. ferox extracts. Finally the extracts showed no toxic activity against the normal foetal lung fibroblasts, Chang and C2C12 cells validating the safety of this plant for human use. V The results in conjunction with literature findings show A. ferox to be a promising source of drugs and therapeutic agents. Due to the fact that traditional healers already rely on it as treatment for different ailments, it is important that the safety of the plant for use has been validated though other studies and clinical trial still need to be done to fully confirm this. All the information gathered also showed this plant to be of great benefit against major health problems, responsible for millions of deaths each year such as cancer, cardiovascular and inflammatory diseases, and diabetes. There is however still a great need for more investigation to be done on this plant against a vast majority of organisms and diseases so as to fully benefit from it.

Thesis (MTech. Nature Conservaion) -- Tshwane University of Technology 2013. / The aim of this study was to determine the current population status of Aloe peglerae in the Magaliesberg Mountain Range.

Department of Food Science and Technology / MSCPNT

Herbal remedies are commonly used in developing countries for the treatment of various diseases, including constipation. The rationale for utilizing medicinal plants for the treatment of diseases rested largely on the belief that they are safe and free of side effects. However, there is limited scientific evidence on the safety and efficacy of these herbal medicines to back up their continued therapeutic application. Aloe ferox Mill. (Aspodelaceae), known as Cape aloe, locally called ikhala is a medicinal plant used by the people of the Eastern Cape Province for the treatment of gastrointestinal problems and constipation. The plant is a perennial shrub with thick succulent leaves bearing brown thorns on the margin and bright orange flowers arranged in oval lanceolate. It occurs in all weather in bush veld, road side, gardens and undisturbed places. According to the ethnomedicinal information, A. ferox is used as purgative. This research project was therefore designed to evaluate its ability in the treatment of constipation and to investigate its possible toxicological property. At the beginning of this programme, a survey of plants used for the treatment of constipation in Nkonkobe Municipality of the Eastern Cape Province was carried out using a questionnaire, which was administered to herbalists, traditional healers and rural dwellers. The study revealed 10 plant species from 8 families that are used for the treatment of constipation in the province. Four plants, Aloe ferox Mill, Boophone distischa L.f Herb, Alepidea amatybica Eckl and Artemisia afra Jacq, were repeatedly mentioned. Based on the frequency of usage, perceived efficacy and availability to the rural dwellers and the traditional healers, Aloe ferox was the most commonly used of the plants for the treatment of constipation. The plant was thus, chosen for the study. The invivo laxative effect of the aqueous extract of Aloe ferox in the treatment of loperamide-induced constipation in Wistar rats was investigated at varying concentrations. The leaf extract at all the dosages investigated (50, 100 and 200 mg/kg body weight) improved intestinal motility, increased fecal volume and normalized body weight in the constipated rats. This was an indication of its laxative properties. However, the laxative property of the herb at 200 mg/kg body weight of the extract showed best efficacy and compares favourably well with senokot, a standard laxative drug. These findings have therefore, lent scientific credence to the folkloric use of the herb by the people of the Eastern Cape of South Africa as a laxative agent. Toxicological evaluation of aqueous leaf extract of Aloe ferox in loperamide-induced constipation was studied at 50, 100, and 200 mg/kg body weight. The oral administration of the extracts did not show any significant effect on the liver and kidney body weight ratios as well as the kidney and liver function indices. The extracts, at all the dosages investigated, did not alter the levels of creatinine, uric acid, urea, calcium and potassium ions. Similarly, the levels of total protein, albumin, bilirubin and gamma glutamyl transferase (GGT) were not significantly different from the control. The plant extract appreciably normalized the elevated activities of alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the untreated constipated rats following treatment with the extract. The extract did not show a significant effect on the hematological parameters except for the increase in the lymphocyte count in the untreated constipated rats, which was attenuated after administering the herb. ThThe available evidence in this study suggests that A. ferox may be safe as an oral remedy for constipation. Generally, the effect of the extract compared favourably well with senokot, a recommended drug for the treatment of constipation. The antioxidant activities against 1, 1 diphenyl- 2 picrylhydrazl (DPPH), 2,2’ – azinobis [3- ethylbenzothiazoline -6- sulfonic acid] diammonium salt (ABTS), hydrogen peroxide (H2O2), Nitric oxide (NO), lipid peroxidation and the ferric reducing agents were investigated spectrophotometrically. Alkaloids, saponins, tannins, total phenols, flavonoids, flavonols and proanthocyanidin were also determined to assess their effects on the antioxidants activity of this plant. The phytochemical content of the ethanol and acetone extracts were consistently high compared to other solvents extracts. The level of tannins was not significant (P > 0.05) as compared with other solvent extracts. The free radical scavenging activity of the extracts was high even at lower concentrations (0.025 mg/ml) except in DPPH and lipid peroxidation. The ferric reducing potential of the extracts was concentration dependent and significantly different from Vitamin C and butylated hydroxytoluene (BHT) that were used as standard drugs. The present study showed a high level of scavenging activity of the leaf extracts of Aloe ferox in all the solvent extracts. Both ethanol and methanolic extract showed potent antioxidant activities than acetone and aqueous extracts. The study indicated that the leaf extracts of Aloe ferox might be a valuable source of natural antioxidant for both medicine and food industries. A. ferox leaf consists of the gel, latex and mesophyll layer; however, the main active constituents of the latex and the leaf exudate of Aloe ferox are anthraquinones which are believed to be responsible for the laxative property. The laxative compound in Aloe ferox leaf extract was isolated and characterized by extracting the plant material in methanol and extract suspended in distilled water. Partitioning was done with n-hexane, ethyl acetate and butanol respectively and was co-spotted with the over-the-counter (OTC) laxative drugs. This led to the successive column chromatography and thin layer chromatography (TLC) of the most active ethyl acetate fraction on silica gel with benzene/ethanol/ammonia hydroxide (BEA: 90:10:1), ethyl acetate/methanol/water (EMW: 40:5.4:5) and chloroform/ethyl acetate/formic acid (CEF: 50:40:10) as the mobile phase. The successive chromatograph and TLC afforded two compounds of Rf 0.420 (blue) and 0.831 (yellow) with the over-the-counter (OTC) drugs. These compounds were not totally elucidated due to their small quantity and instability. However, hydroxyl (OH) and carboxyl groups (COOH) was established as common to the extracted compounds, which might be responsible for the biological activity recorded for the plant extract.