South African Journal of Botany

Published by Elsevier
Online ISSN: 0254-6299
Publications
Structure of PGG (compound 1 ). 
Cholinesterase inhibition activity of selected Korean medicinal plants.
Article
The search for a novel pharmacotherapy from medicinal plants for neurodegenerative disorders has significantly advanced. Therefore, the present study was performed to evaluate the anticholinesterase activities of one hundred medicinal plants in Korea, where Terminalia chebula (T. chebula) fruits showed significant acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitions. Further bioassay monitored phytochemical exploration led to the isolation of 1,2,3,4,6-penta-O-galloyl-β-d-glucose (compound 1), which showed significant AChE and BChE inhibitory effects with IC50 values of 29.9 ± 0.3 µM and 27.6 ± 0.2 µM, respectively. The inhibitory effect of compound 1 towards acetylcholinesterase was also evaluated using TLC and compared with tacrine as the positive control; the positive effect was confirmed. Furthermore, compound 1 also displayed strong antioxidant activity by the FRAP assay (IC50 = 4.6 ± 0.2 µM). In conclusion, compound 1 may prove to be a potential natural anti-Alzheimer source based on noteworthy AChE and BChE inhibitions, and strong antioxidant activity.
 
Article
The impacts of invasive alien plants (IAP) and their subsequent clearing by the Working for Water Programme (WfW) on (a) overstorey (woody plant) vegetation structure, (b) invasion intensity (overstorey aerial cover of woody alien plants) and (c) ground cover, in a temperate to subtropical riparian ecosystem were studied in 1996/7 and again in 2005, in order to provide a longer-term perspective on the effectiveness of WfW clearing. Forty 1000 m2 plots were surveyed and resurveyed, comparing between (a) higher altitude Grassland and lower altitude Savanna, (b) high (> 50% invasion intensity) versus low (< 50% invasion intensity) alien invasion sites, and (c) WfW cleared versus uncleared sites (the three ‘treatments’). Pre-clearing estimates from cut stumps in 1996/7 indicated high alien invasion intensities of 72 ± 8% in Grassland and 69 ± 11% in Savanna. From 1996/7 to 2005 there was a large decrease in aerial cover of alien trees of > 5 m and to a lesser extent 2–5 m in height, and a large increase in alien plants of < 2 m. Hence WfW was initially successful, with the original tall Eucalyptus grandis tree layer largely removed. However, total invasion intensity remained unchanged over the first decade (30.4 ± 4.6% in 1996/7, 31.9 ± 3.2% in 2005). From 1996/7 to 2005, grass and herbaceous cover decreased, while bare soil and litter increased, indicating reduced surface stability. This was in response to (a) the major flood event of February 2000, (b) the effects of IAP invasions and (c) WfW clearing. Total ground vegetation cover was negatively related to alien aerial cover in both biome reaches in 1996/7 and 2005. By 2005, there were no longer any differences in the aerial cover of woody alien plants in response to the original 1996/7 invasion intensity or clearing ‘treatments’, and hence progressive homogenization of IAP cover. Aerial cover of woody indigenous plants also responded negatively to increasing alien aerial cover in 1996/7 and 2005 in both Savanna and Grassland. In conclusion, the nature of the IAP problem has changed from dealing largely with relatively few large E. grandis trees in the mid-90s, to the present large suite of invasive species with numerous smaller individuals. This has implications for the time needed for clearing. This is one of few studies to have assessed the initial and longer-term (1995–2005) effectiveness of WfW clearing operations. It shows that improved IAP clearing protocols are needed. More follow-up treatments are recommended to ‘capture’ alien resprouts and new seedlings before they establish and reproduce. Secondly, integrating clearing with restoration of the tall indigenous riparian canopy tree species in heavily invaded sites would help to shade out many alien recruits.
 
Article
The number of botany students, botany classes, botany departments in universities and botanists attending conventions has been declining over many years in North America. This is part of a general trend throughout the field of organismal biology, not just botany. The history leading up to the situation today in North America, is discussed and reasons are given for this trend over the last century of time. Seven ways to keep botany a viable occupation are discussed otherwise botany, in the 21st century, may go the way of the dinosaur.
 
Article
Investigation of the ethyl acetate leaf extract of Trichilia dregeana for anti-inflammatory activity using bioassay-guided fractionation led to the isolation of cycloart-23-ene-3,25-diol. The compound was tested for anti-inflammatory activity using the cyclooxygenase assays (COX-1 and COX-2), anti-cholinesterase activity using the microplate assay and investigated for potential mutagenic effects using the Ames test. In the cyclooxygenase assays, cycloart-23-ene-3,25-diol showed inhibitory activity against COX-2 (80%) at a concentration of 100 μM (IC50 was 40 μM). At the same concentration, the compound showed weak activity against COX-1 (56%) with an IC50 value of 97 μM. In the anti-cholinesterase test, the compound had a weak inhibitory effect against acetylcholinesterase (53%) when tested at a concentration of 0.4 mM. No potential mutagenic effects were observed in the Salmonella microsome assay (TA 98). Isolation of the bioactive compound and the activity observed in this study may explain in part the use of the tree in traditional medicine as a crude anti-inflammatory drug.
 
Article
An account is given of pseudo-vivipary (vegetative apomixis) in South African Cyperaceae. Taxa exhibiting this reproductive strategy are tabled. Stress that effects plant population deterioration and eventual non-survival is attributed as causative; in particular water stress, either as maintained inundation or undue depletion. Habitat conditions appear to govern the balance between fruiting and pseudo-vivipary. This balance is changeable from season to season, area to area, species to species and within species. The viability of seeds within fruits formed upon inflorescences that also are in part pseudo-viviparous has not been tested.
 
Article
The study evaluated the forage productivity and water use of four leguminous grasses namely alfalfa (Medicago sativa L.), vetch (Astragalus adsurgens Pall.), sainfoin (Onobrychis viciaefolia Scop.) and Lespedeza davurica grown in semiarid region on the Loess Plateau of China. The experiments were conducted in the years 2001–2004 where each grass was grown on four 7 m × 6 m experimental plots. The aboveground biomass production considered the sum of dry litter and standing parts was measured every year at the end of growth season. Soil water measurements were made from soil drill (Ø4 cm cores) every month for soil extending to a depth of 300 cm in the first and second year and up to 500 cm in the rest of the period.The yearly biomass production, soil water storage volume as well as its change, monthly rainfall and water consumption of each grass were statistically analyzed. A linear correlation was used to analyze the biomass production and total water used in evapo-transpiration. Stepwise regression was performed to evaluate the relationship between biomass production and monthly rainfall and soil water storage to explain the differences among grasses. The analysis showed that biomass production of both the vetch and L. davurica were significantly (P < 0.05) correlated with total precipitation of April to June while that of sainfoin and alfalfa was significantly (P < 0.05) correlated with total precipitation of the growth season (April to October). All four grasses exhibited positive (P < 0.05) aboveground biomass production response to soil water usage, but there is difference among. Alfalfa, vetch and sainfoin had a drying effect at a depth less than 2.0 m and consistently showed profiles with the lowest soil water content. Profiles with the lowest soil water content also had greater herbage growth and greater depths of water extraction.
 
Known geographical occurrence of Hydnora abyssinica and H. africana in South Africa and Swaziland. [QDS for H. abyssinica obtained from PRE, NH, PUC, KNP and a specimen photographed in the Kruger National Park by O. Maurin from the University of Johannesburg (Fig. 8)]. * Specimen (Smith 1009 PRE); refer to note in text.  
(A) Harvesting localities for Hydnora abyssinica cited by traders in Faraday and Warwick in 2009; (B) Past harvesting sources of Hydnora spp. cited in three surveys conducted between 1986 and 2001 by A.B. Cunningham and V.L. Williams.  
Emerging flowers of Hydnora abyssinica observed growing under Berchemia discolor (Klotzsch) Hemsl. (Rhamnaceae) at Tshokwane, Kruger National Park (2431DD), by Guin Zambatis (KNP Herbarium, Skukuza) in December 2009. White osmophores are evident at the tips of the 4-merous salmon-coloured perianth lobes. There are three H. abyssinica specimens at KNP herbarium (van der Schyiff 3464 KNP; Zambatis 2006 KNP; Anon. s.n. KNP!), one collected in 1957.  
Longitudinal sections of a 4-merous H. abyssinica flower photographed in the Biyamiti area of the Kruger National Park (2531BC) by O. Maurin of the University of Johannesburg in December 2005. The osmophore (os) is at the tip of the perianth lobe (pl) on the interior surface of each tepal. The fused 4-lobed antheral ring (an) is at the base of the androecial chamber, and the 4-lobed stigmatic 'cushion' (st) is at the base of the gynoecial chamber above the ovary and the placenta (pc). The flower is attached to the rhizome by the stalk at the base of the ovary. The flower on the extreme right of the picture is intact and shows the exterior appearance of the flower.  
Article
Large quantities of plants are traded annually in South Africa's traditional medicine or ‘muthi’ markets. A resource in high demand in the Faraday (Johannesburg) and Warwick (Durban) markets is uMavumbuka, a root holoparasite usually identified as either Hydnora africana Thunb. or Sarcophyte sanguinea Sparrm. subsp. sanguinea. However, rhizomes regularly observed in Faraday between 1994 and 2008 did not resemble either species, thereby suggesting that a third, and undocumented, species was being harvested. This was confirmed when the rhizomes were identified as H. abyssinica A.Br. by an American parasitic plant expert. An ethno-ecological study was initiated to verify its occurrence in selected muthi markets. The study further aimed to investigate the distribution of H. abyssinica through trader interviews, host species localities and some previously misidentified herbarium specimens. The study revealed that H. abyssinica was the only uMavumbuka species present in Faraday and Warwick in 2009. Furthermore, the rhizomes were being harvested in KwaZulu-Natal—an area not previously known to be part of its distribution range. Re-evaluated herbarium vouchers and recent photographs taken in the Kruger National Park have confirmed that H. abyssinica occurs in KwaZulu-Natal, Limpopo, Mpumalanga, Gauteng and Swaziland and hence eastern southern Africa. Fragments of Acacia xanthophloea Benth. roots were identified on 93% of the samples that had host roots attached, and we suspect that H. abyssinica follows the distribution of A. xanthophloea in suitable habitats north from KwaZulu-Natal and adjoining the South African border with Swaziland and Mozambique. Acacia karroo Hayne and A. grandicornuta Gerstner have also been positively identified as host species in South Africa from herbarium records. Plant harvesters in the markets cited the common names of several other species that uMavumbuka “grows under” that may be identified as hosts to H. abyssinica in the future. The collection of specimens in areas identified by the harvesters and in areas of suitable habitat is important to verify the occurrence, distribution and habitat of H. abyssinica in eastern southern Africa.Research Highlights►Hydnora abyssinica rhizomes were identified in traditional medicine markets in South Africa ►Rhizomes harvested in KwaZulu-Natal, further east than known from published distribution records ►Some H. abyssinica herbarium specimens had been incorrectly identified as H. africana ►Ethno-ecological validation of the occurrence of H. abyssinica in South Africa ►Distribution map updated to include new herbarium evidence and plant sightings
 
Article
We examined pollination biology of Acacia nigrescens Oliver, flowering at the end of the dry season in Kruger National Park, South Africa. A. nigrescens produces small quantities of concentrated nectar, and has abundant pollen resources available to potential pollinators. We recorded large numbers of insect visitors and most fruit set on the tops of trees, beyond the reach of ungulate browsers such as giraffes (which consume a substantial proportion of A. nigrescens flowers). Wasps, flies and solitary bees were the most numerous visitors and are likely to play a significant role in pollination.
 
Article
Salinity stress remains one of the world's oldest and the most serious environmental problem, which substantially hampers crop productivity in arid and semi arid areas. This problem has been addressed by expensive and energy depleting soil reclamation measures. However, a cheaper sustainable alternative lies in the development of salt tolerant crop cultivars. In this study, we tested salinity tolerances of 98 wheat accessions originating from Pakistan, India and Mexico from measurements of their shoot and root growth in cultures containing 0, 10 and 15 dS/m of NaCl. Genotypic responses were compared from measures of absolute and relative salt tolerances. Differential growth reductions to increased salinity were observed in the wheat accessions with those originating from Mexico exhibiting significantly greater salinity tolerances overall than those originating from Pakistan. No significant correlations were found between plant salinity tolerances and their vigour as measured by relative growth rates in controls; with relative growth rates of different genotypes grouped on the basis of different geographic origin and different genes of various stresses also not differing significantly from each other. Estimated broad-sense heritabilities indicated that phenotypic variance exceeded that of genotypic by nearly two orders of magnitude. These findings indicate that the genetic improvement of salt tolerance in wheat through selection will be problematic due to masking effects of the environment, and imply rigorous and careful selection of salt tolerant accessions.
 
Article
The effect of employing a RITA® system in one or both of somatic embryo induction and germination stages was investigated, and it was deemed far superior to a semi-solid (agar) substrate in terms of in vitro plant yields for sugarcane genotype N41. Approximately 18,000 plants/leaf roll were obtained in vitro in 12 weeks, when both culture stages were undertaken using temporary immersion, compared with approximately 2000 plants/leaf roll produced on semi-solid medium. However, due to hyperhydricity, only ~ 34% of the plants produced in RITA® survived acclimatization. To overcome this, and realize the potential yields of the RITA® system, various culture conditions were investigated, viz. nutrient and sucrose supplies, a rockwool substrate and the immersion regime. Of these, increasing the resting time between immersions from 1 min/12 h to 1 min/72 h, and lowering MS nutrient to 1/2 strength, proved the most beneficial, resulting in 60% acclimation success. Genetic fidelity of these plants was investigated by AFLP analyses where only 0–0.9%, of polymorphic bands were scored compared with the conventionally- propagated N41 control. Phenotypic characterization of plants grown in the field for 6 months showed that, although all in vitro derived plants had a reduced stalk diameter relative to the control, there were no significant differences regarding stalk mass, height and population.Research highlights► Results confirm that in vitro yields are greater RITA® vessels instead of agar. ► 1/2 MS and 1 min/72 h immersion regime overcame shoot hyperhydricity in RITA®. ► The benefit of such a long resting time between immersions has not been reported. ► The established protocol yielded ± 6000 acclimated plants/leaf roll. ► AFLP and phenotypic tests showed few differences between ex-vitro and control plants.
 
Structures of vernolide (1) and vernodalin (2). 
In vitro antiplasmodial activity of VLC fractions of V. colorata against P. falciparum (CQS) D10 strain
Article
Vernonia colorata is used throughout Africa to treat various ailments. Its antiplasmodial activity has been widely reported. Using bioassay-guided fractionation, we isolated two antiplasmodial compounds — vernolide (IC50 = 1.87 μg/ml) and vernodalin (IC50 = 0.52 μg/ml) with selective indices of 1.02 and 2.79 for vernolide and vernodalin respectively. These compounds are non-specific towards parasites.
 
Chemical structures of compounds isolated from the stem bark of T. annobonae.  
Article
This study was designed to evaluate the antimycobacterial, antibacterial and antifungal activities of the methanol extract from the stem bark of Thecacoris annobonae Pax & K. Hoffm, that of aristolochic acid I (1) and other isolated compounds. The microplate alamar blue assay (MABA) and the broth microdilution method were used to determine the minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of the above samples. The H+-ATPase-mediated proton pumping assay was used to evaluate a possible mechanism of action for both the methanol extract and aristolochic acid I. The results of the MIC determinations showed that the methanol extract and aristolochic acid I prevent the growth of all studied organisms. The results obtained in this study also showed that the methanol extract as well as aristolochic acid I inhibited the H+-ATPase activity. The overall results provided evidence that the methanol extract of T. annobonae might be a potential source of new antimicrobial drug against tuberculosis, and some bacterial and fungal diseases, but should be consumed with caution, bearing in mind that the main active component, aristolochic acid I is a potentially toxic compound.
 
Article
The aim of this study was to evaluate the antimicrobial activity of the crude extract of the twigs of Dorstenia turbinata (DTT) as well as that of five of the nine compounds isolated from this extract, namely 5-methoxy-3-[3-(ß-glucopyranosyloxy)-2-hydroxy-3-methylbutyl]psoralen (1), 5-methoxy-3-(3-methyl-2,3-dihydroxybutyl)psoralen (2), (2′S, 3′R)-3′-hydroxymarmesin (3), 4-hydroxy-3-methoxybenzaldehyde (4) and 4-methoxyphenol (5). Gram-positive, Gram-negative bacterial species as well as fungi were used. The agar disc diffusion test was used to determine the sensitivity of the tested samples while the well micro-dilution was used to determine the minimal inhibition concentrations (MIC) and the minimal microbicidal concentration (MMC) of the active samples. The results of the disc diffusion assay showed that the crude extract (DTT), compounds 1 to 3 were able to prevent the growth of all the tested pathogens at the tested concentrations. Compounds 4 and 5 showed moderate and selective activities. The results of MIC determinations indicated values ranging from 19.53 to 78.12 µg/ml for the DTT and from 9.76 to 78.12 µg/ml for compound 2. The MIC values recorded on 91% of the tested organisms for compounds 1 and 3. The lowest MIC value for the crude extract of D. turbinata (19.53 µg/ml) was noted on Trichophyton rubrum and Escherichia coli. The corresponding value for the tested compounds (9.76 µg/ml) was obtained with 2 and 3 on T. rubrum. The antimicrobial activity of this plant as well as that of compounds 1-2 is being reported for the first time. The overall results provide promising baseline information for the potential use of the crude extracts from DTT as well as some of the isolated compounds in the treatment of bacterial and fungal infections.
 
Article
The methanol extract from the stem bark of Terminalia superba (TSB), fractions (TSB1–7) and two compounds isolated following bio-assay guided fractionation namely 3,4′-di-O-methylellagic acid 3′-O-β-d-xylopyranoside (1) and 4′-O-galloy-3,3′-di-O-methylellagic acid 4-O-β-d-xylopyranoside (2) were evaluated for their antimycobacterial, antibacterial and antifungal activities. The broth microdilution, the microplate Alamar Blue assay (MABA) and the agar disc diffusion methods were used for the investigations. The results of the antimycobacterial assays showed that the crude extract, fractions TSB5–7 and compound 1 were able to prevent the growth of all the studied mycobacteria. The lowest minimal inhibitory concentration (MIC) value of 39.06 µg/ml for this extract was recorded on both M. smegmatis and M. tuberculosis MTCS2. The corresponding values were 19.53 µg/ml and 4.88 µg/ml for fractions and compounds respectively. The MIC determination results on other organisms indicated values ranging from 19.53 to 78.12 µg/ml for TSB and compound 2 on 90.9% of the tested organisms, meanwhile compound 1 as well as fractions TSB 6 and 7 exhibited detectable MIC values on all studied microorganisms. The overall results provide promising baseline information for the potential use of the crude extract from T. superba, fractions 6–7 and the tested compounds in the treatment of tuberculosis, bacterial and fungal infections.
 
Article
An investigation of leaf indumentum, the identification of the essential oil components and assessment of various biological activities of Salvia albicaulis and S. dolomitica essential oils were carried out. Non-glandular and both peltate and capitate glandular trichomes were identified using scanning electron microscopy. The essential oil of S. albicaulis was dominated by oxygen-containing sesquiterpenes (47%), with viridiflorol (25%), 1,8-cineole (9%) and limonene (9%) as major components. S. dolomitica oil was mainly composed of oxygen-containing monoterpenes (72%), with geraniol (20%), linalyl acetate (20%) and linalool (17%) being the major components. The in vitro pharmacological properties of the essential oils were also evaluated. Antibacterial activity was assessed against Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 11778), Escherichia coli (ATCC 8739) and Klebsiella pneumoniae (NCTC 9633). The oils showed poor activity against E. coli (MIC value > 32 mg ml− 1), while moderate activity was obtained against the other pathogens (MIC values between 2 and 12 mg ml− 1). The results of the antiplasmodial activity evaluated against the chloroquine-resistant FCR-3 strain showed that both S. albicaulis and S. dolomitica essential oils exhibited antiplasmodial activity with IC50 values of 6 ± 2 and 5 ± 1 μg ml− 1, respectively. The two oils also displayed anti-inflammatory activity (IC50 value: 39 ± 4 and 65 ± 6 μg ml− 1, respectively). Poor anti-oxidant activity was obtained against the DPPH·and the ABTS·+ radicals (IC50 values > 100 μg ml− 1). The toxicity profile of the two oils evaluated against the human kidney epithelium cells indicated some degree of toxicity in comparison to 5′-fluoro-uracil.
 
inhibitory concentrations of Lippia extracts and compounds against four human pathogens.
Article
Lippia javanica and Lippia scaberrima are used as herbal remedies and are commercially traded as health teas in southern Africa under the brands “Mosukujane” and “Musukudu”, respectively. This study evaluates the relationship between the presence of phenolic compounds and the antioxidant activities of infusions prepared from four Lippia species (L. javanica, L. scaberrima, L. rehmannii and L. wilmsii) indigenous to South Africa. The antioxidant activities of the infusions, determined by the 2,2-diphenylpycrylhydrazyl (DPPH) method, were also compared to those of popular black, green and herbal tea brands. Of the four indigenous species, infusions of L. javanica and L. wilmsii exhibited the highest antioxidant activities (EC50: 358 and 525 µg/ml, respectively) and contained the most phenolic compounds (14.8 and 14.5 mg/ml of dry weight gallic acid equivalent, respectively). Antibacterial activities of methanolic extracts of the four Lippia species were determined against four human pathogens (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa). The extract of L. javanica was the most active against all the pathogens tested. Those Lippia species (L. javanica and L. wilmsii) previously reported to produce higher levels of the pharmacologically active phenylethanoid glycosides verbascoside and isoverbascoside, portrayed stronger antioxidant and antibacterial activities. This study gives credence to the use of infusions of these Lippia species for their general health benefits.
 
Free radical scavenging activity of the crude extracts from the three Treculia species and vitamin C; values with the same letter are not significantly different (ANOVA, P b 0.05). 
Antitumor activity of the crude extracts from the three Treculia species (TACT: T. acuminata twigs, TACL: T. acuminata leaves, TAT: T. africana twigs, TAL: T. africana leaves, TOT: T. obovoidea twigs, TOL: T. obovoidea leaves), VBS: vinblastin. Values with the same letter are not significantly different (ANOVA, P b 0.05). 
Article
This study was designed to evaluate the antimycobacterial, anti-reverse transcriptase, radical scavenging and antitumor activities of the methanol extracts of the twigs and leaves of three plants of the genus Treculia, namely Treculia obovoidea, Treculia africana and Treculia acuminata. The DPPH radical scavenging assay was used for the antioxidant test while the crown gall tumor assay was used for antitumor evaluation. The INT colorimetry and microplate Alamar blue assay (MABA) were used for antimycobacterial investigations. The results of the antimycobacterial assays, showed that the leaf crude extract of the three Treculia species as well as that from the twigs of T. africana were able to prevent the growth of Mycobacterium smegmatis and Mycobacterium tuberculosis. The lowest MIC value (19.53 µg/ml) was recorded with extract of the leaves of T. africana on M. smegmatis, and those of T. africana and T. acuminata against M. tuberculosis. All studied extracts inhibited at various extents the anti-reverse transcriptase activity at 200 µg/ml. The best IC50 values, 31.1 µg/ml, 29.5 µg/ml and 21.1 µg/ml were recorded respectively with the extracts of the leaves of T. obovoidea, T. acuminata and T. africana. Results of the antioxidant activity indicate a dose-dependent ability of sample to scavenge the DPPH radical. The lowest IC50 values were obtained with extracts of the leaves of T. acuminata (56.3 µg/ml) and T. obovoidea (55.9 µg/ml). Pronounced tumor-reducing activity was observed with the extracts of the leaves of T. africana (89.67%), T. acuminata (92.16%), T. obovoidea (96.67%) and that of the twigs of T. acuminata (87.18%). The overall results provide evidence that plants of the genus Treculia might be potential sources of antitubercular, anti-HIV and antitumor compounds.
 
Effect of temperature and explant orientation on bulblet induction per leaf explant and bulblet mass of E. zambesiaca.
Effect of four photoperiods on bulblet induction in leaf explants from E. zambesiaca.
Effect of carbohydrate type and concentration on bulblet induction of E. zambesiaca leaf explants.
Article
Eucomis species having considerable horticultural potential are used in African traditional medicine to treat various ailments. The effects of environmental and physiological parameters on the initiation and growth of bulblets using leaf explants were investigated. These included the effect of temperature (10, 15, 20, 25 and 30 °C), photoperiod (8 h light, 16 h light, continuous light and continuous dark), carbohydrates (sucrose, fructose and glucose) at different concentrations and combinations as well as various plant growth regulators; gibberellic acid (GA3), indole-3-butyric acid (IBA), napthaleneacetic acid (NAA), N6-benzyladenine (BA), zeatin and others. Liquid shake and liquid static cultures versus solid cultures were investigated. Maximum number of bulblets per leaf explant was obtained at 20 °C, with an average of 3 bulbs per leaf explants and a bulblet mass of 57 mg. An 8 h light cycle produced 1.38 bulbs per leaf explant, at a mass of 42 mg. Fructose at 3% produced an average of 1.18 bulbs per leaf explant, 3.39 mm wide and weighing 56.6 mg. Of the plant growth regulators, 4.90 µM IBA was found to be the optimum treatment for bulblet induction, with an average bulb diameter of 4.36 mm and a mean bulblet mass of 79.07 mg. Liquid shake cultures exhibited poor growth while bulblet, leaf and root growth was improved in liquid static cultures. Successful micropropagation from leaf explants established that leaf explants can be used as an alternative explant source to bulbs. This protocol allows for the fast and economic mass propagation of Eucomis plants.
 
Structures of (1) crinine, (2) buphanamine, (3) buphanidrine, (4) buphanisine and (5) distichamine. 
1 H NMR (300 MHz, CDCl 3 ) data of alkaloids isolated from Boophone disticha.
IC 50 determinations for buphanamine ( ○ ), buphanidrine ( □ ), buphanisine 
IC 50 determinations for distichamine ( ▿ ) and buphanidrine ( □ ) in the 
Article
Boophone disticha L. Herb (Amaryllidaceae) is used in traditional medicine for treatment of painful wounds, headaches, skin disorders, inflammatory conditions, rheumatic pains and anxiety. At least eight alkaloids have been characterized and reported in the literature. Of these buphanidrine and buphanamine have affinity to the serotonin transporter (SERT). Alkaloids from other Amaryllidaceae species have also shown affinity to SERT. In this study, an ethanol extract was prepared from dry bulbs. Through HPLC–UV separation five peaks were collected and characterized by LC-MS and 1H NMR and led to the identification of crinine, buphanamine, buphanidrine, distichamine and buphanisine. The activity of these compounds was tested in a binding assay using [3H]-citalopram as ligand and a functional SERT inhibition assay utilizing COS-7 cells expressing hSERT. The four active compounds, buphanamine, buphanidrine, buphanisine and distichamine, had IC50-values of 55 µM, 62 µM, 199 µM and 65 µM respectively, in the binding assay. The alkaloids also showed activity in the functional assay, buphanidrine and distichamine being the most active with IC50-values of 513 µM and 646 µM, respectively.
 
Non-volatile secondary metabolites identified from Artemisia afra.
continued )
Article
The genus Artemisia consists of about 500 species, occurring throughout the world. Some very important drug leads have been discovered from this genus, notably artemisinin, the well known anti-malarial drug isolated from the Chinese herb Artemisia annua. The genus is also known for its aromatic nature and hence research has been focussed on the chemical compositions of the volatile secondary metabolites obtained from various Artemisia species. In the southern African region, A. afra is one of the most popular and commonly used herbal medicines. It is used to treat various ailments ranging from coughs and colds to malaria and diabetes. Although it is one of the most popular local herbal medicines, only limited scientific research, mainly focussing on the volatile secondary metabolites content, has been conducted on this species. The aim of this review was therefore to collect all available scientific literature published on A. afra and combine it into this paper. In this review, a general overview will be given on the morphology, taxonomy and geographical distribution of A. afra. The major focus will however be on the secondary metabolites, mainly the volatile secondary metabolites, which have been identified from this species. In addition all of the reported biological activities of the extracts derived from this species have been included as well as the literature on the pharmacology and toxicology. We aim at bringing together most of the available scientific research conducted on this species, which is currently scattered across various publications, into this review paper.
 
Article
Artemisia afra is one of the most widely used medicinal plants in African traditional medicine and is commonly administered in polyherbal combinations to treat respiratory infections. Focussing on plant volatiles, the aim of this study was to provide scientific evidence for the antimicrobial activity of A. afra (principle plant) in combination with essential oils from three medicinal aromatic plants; Agathosma betulina, Eucalyptus globulus and Osmitopsis asteriscoides. In vitro minimum inhibitory concentration (MIC) assays were undertaken on four pathogens (Enterococcus faecalis ATCC 29212, Moraxella catarrhalis ATCC 23246, Klebsiella pneumoniae NCTC 9633 and Cryptococcus neoformans ATCC 90112) to determine antimicrobial efficacy of the oils and their combinations. The fractional inhibitory concentration (FIC) and isobolograms were used to interpret pharmacodynamic interactions such as synergy, antagonism or additive profiles. The antimicrobial activity of the individual oils mostly displayed moderate activity. Predominantly, additive interactions were noted. The most prominent synergistic interaction (FIC value of 0.5) was observed when A. afra was combined with O. asteriscoides in the 8:2 ratio (eight parts A. afra with two parts O. asteriscoides) against C. neoformans. No antagonistic interactions were evident.
 
Kappia lobulata, roots and tubers (photo by AP Dold). 
Kappia lobulata, plant climbing on the stem of Zanthoxylum capense (photo by AP Dold). 
Kappia lobulata flower as seen from above (photo by AP Dold). 
Kappia lobulata, a: fruit with paired follicles; b: seed ventral surface; c: seed dorsal surface and proximal coma. Scale bars: a=10 mm; b, c=5 mm (Sketch by AP Dold from Dold 4461). 
Kappia lobulata, a: pollen translator and b: decussate pollen tetrad (micrographs by RL Verhoeven from Dold 4461). Scale bars: a=100 μ m, b=10 μ m. 
Article
Kappia, a new genus from the Fish River Valley in the Eastern Cape Province, South Africa is presented. At first described as Raphionacme lobulata Venter and R.L.Verh. [Venter, H.J.T., Verhoeven, R.L. 1988. Raphionacme lobulata (Periplocaceae), a new species from the eastern Cape Province, South Africa. South African Journal of Botany 54, 603–606.] based on a single specimen collected in 1936, recently discovered plants of this species proved it to be a new genus. In habit Kappia resembles Baseonema Schltr. and Rendle, Batesanthus N.E.Br., Mondia Skeels and Stomatostemma N.E.Br. However, as far as floral structure is concerned, Kappia reveals more affinity with Raphionacme Harv. DNA sequence data show Kappia to be distinct from Batesanthus, Mondia and Raphionacme Harv. and weakly supported as a sister to Stomatostemma.
 
Article
Working for Water forms part of the Expanded Public Works Programme of the South African Government, aimed at the sustainable management of natural resources through the control and management of invasive alien plants while enhancing socio-economic empowerment in South Africa. The programme's name was taken from one of the original motivations: namely, reducing the impacts of invasive alien trees on water resources. A number of studies have looked at the potential impacts of the programme but only one or two have used actual management data to quantify its costs and benefits. This paper is the first, in hopefully a series of papers, on the costs and impacts of the programme over recent years. The paper focuses on the extent, costs and impacts of clearing invasive alien plants from riparian areas. Data were extracted from the Working for Water Information Management System (WIMS) and analysed to assess clearing costs and estimated impacts of clearance on water resources. Some of the most significant findings of the study again illustrate the need to treat invasions as early as possible. Very scattered (1–5%) invasions of selected species for example were between 3 and 25 times cheaper to clear than closed canopy stands (75–100%). On the other hand, unit reference values, used to compare clearing operations in terms of cost efficiency in generating extra water yield, were much higher for low levels of invasion than denser invasions, to the extent that the former's viability could be questioned by the uninformed. However, this was only assessed in terms of extra water generated and not in terms of volumes of water secured, as invasive alien plants spread and become denser if not actively controlled. If left unchecked, water losses increase, which makes the clearing of light infestations much more viable. Overall, it is estimated that around 7% of riparian invasions have been cleared, resulting in significant yield increases. The increased estimated yield of 34.4 million m3 is about 42% of the yield of the new Berg River Scheme in the Western Cape (81 million m3). The investment in clearing species known for excessive water use from riparian areas, at a cost of R116 million, was found to be a very good investment. However, it is important to note that the clearing of invasive alien plants will seldom result in the total elimination of shortfalls in water supply and should be seen as part of a package of water resource options to optimize supply, aimed at minimizing wastage of water.
 
The study area in Maputaland, South Africa, with Tembe Elephant Park, Tshanini Community Conservation Area and the Manqakulane Village. 
A linear regression on stem diameter size classes in the Sand Forest communities. (a) Short Sand Forest and (b) Tall Sand Forest in Tembe Elephant Park (TEP) and Tshanini Community Conservation Area (TCCA). The dotted lines represent the 95% confidence intervals. 
A linear regression on stem diameter size classes in the closed Woodland communities. (a) Closed Woodland Thicket and (b) Closed Woodland on Sand in Tembe Elephant Park (TEP), Tshanini Community Conservation Area (TCCA) and the Manqakulane village zone area (MRC). The dotted lines represent the 95% confidence intervals. 
A linear regression on stem diameter size classes in the Open Woodland on Sand in Tembe Elephant Park (TEP), Tshanini Community Conservation Area (TCCA) and the Manqakulane village zone area (MRC). The dotted lines represent the 95% confidence intervals. 
Article
This study evaluated the effects of humans and herbivores on woody vegetation structure in the woodlands and forests of Maputaland. The woody vegetation structure of plant communities at three sites within a similar environment but under different utilisation regimes since the early 1990s was evaluated by means of a stem diameter and tree height class analysis. The effects of human utilisation were evaluated on the land of the rural Manqakulane community; herbivore utilisation was evaluated in the Tembe Elephant Park; and because of the low levels of utilisation since 1992 the vegetation in the Tshanini Community Conservation Area was used as a benchmark for the comparisons. In both woodlands and sand forests, utilisation regime resulted in changes in stem diameter size class distributions, although the height structure remained unchanged. In communal land human-associated disturbance promoted the presence of small woody plants. In general, conserved land under animal utilisation, had the least small diameter woody plants, but most of the large trees, whereas in the absence of utilisation intermediate densities of small diameter woody plants were found but low densities of large trees. This study presents the first quantification of significant changes in the woody vegetation structure in Maputaland due to human utilisation, herbivore utilisation, or lack of utilisation. It also provides a timeframe within which land use can cause significant changes in vegetation structure.
 
An analysis of the growth rates of all individuals across species in different size classes over the 71-month survey period (long-term), as well as for first three seasons separately. 
The relationship between wood density and long term growth rate of Sand Forest and woodland species in Maputaland, northern KwaZulu – Natal, South Africa. 
The changes in growth rate in the intervals between successive surveys across the monitoring period for all individuals of Sand Forest versus woodland species. 
A principal coordinate analysis (PCO) on the mean growth increment (per species) between surveys across the entire monitoring period. A.b. = Acacia burkei ; A.q. = Afzelia quanzensis ; A.v. Albizia versicolor ; C.m. = Combretum molle ; C.s. Cleistanthus schlechteri ; D.a. = Drypetes arguta ; D.s. = Dialium schlechteri ; H.u. = Hymenocardia ulmoides ; M.d. = Manikara discolor ; P.l. Psydrax locuplex ; P.o. = Psydrax obovata ; P.m. = Pteleopsis myrtifolia ; R.g. = Rhus gueinzii ; S.b. Sclerocarya birrea ; S.h. = Strychnos henningsii ; S.m. = Strychnos madagascariensis ; S.s. = Strychnos spinosa ; T.s. = Terminalia sericea ; V.l. = Vepris lanceolata ; Circles = woodland species; squares = Sand Forest species; triangles = mixed species. 
monthly and annual rainfall (mm) for the study period as measured at the Shihangwane weather station at the gate of the Tembe Elephant Park
Article
Annual stem circumference growth rates of 23 woody species of the Sand Forest and woodland in Maputaland are presented for the first time. The rare Sand Forest, has been identified as an endemic, diverse vegetation type that is under threat from land transformation and human utilisation outside conservation areas. The growth rate of the selected woody species was evaluated over a 71-month survey that encompassed climatic extremes, oscillating from heavy rainfall to drought in a short period of time. The mean annual stem circumference growth rate among the investigated species varied thirteen fold, from a low of 2.04 mm/yr for Brachylaena huillensis to 26.28 mm/yr for Garcinia livingstonei. When the data of all species were considered, there was a significant positive relationship between stem circumference and growth rate, but no significant relationship between wood density and growth rate. The present results suggest that there is no significant difference in terms of mean annual growth rate between the Sand Forest and woodland vegetation types. In general, woodland species showed larger fluctuations in growth rate and the temporal pattern of Sand Forest species seemed to lag behind that of the woodland species. These trends can in part be ascribed to the woodland species all being deciduous, whereas the Sand Forest suite included both deciduous and evergreen species. Annual growth rates measured from dry season to dry season were not related to the seasonal rainfall pattern, but appeared to be highly dependent on the water availability at the time of the enumeration. The larger size classes reacted sooner to decreased water availability and a reduction in growth of larger trees was accompanied by an increase in growth in the smaller size classes.
 
Correspondence analysis of the 20 most frequent species in the seed bank at habitat scale. Samples were taken from reference (A) and invaded (B) sections of four rivers in the south-western part of the Western Cape, South Africa (see text). Trans = transitional bank zone. A: reference soil samples (Eigenvalue 1: 0.08854; Eigenvalue 2: 0.06451); B: invaded soil samples (Eigenvalue 1: 0.15769; Eigenvalue 2: 0.07022). Species codes: Am = *Acacia mearnsii, C=Crassula sp., Ca= * Conyza albida, Cc=Cliffortia cuneata, Dd=Digitaria debilis, E=Erica sp., Ea= Euryops abrotanifolius, El=Erharta longiflora, Ep=*Euphorbia prostrate, Er=Erepsia sp., Fc=Ficinia anceps, Hh=Helichrysum helianthemifolium, Hr=  
's Community Coefficient (Ss) for comparison between vegetation and seed banks in fynbos riparian plots sampled along four rivers in the Western Cape, South Africa
Article
Riparian zones are complex disturbance-mediated systems that are highly susceptible to invasion by alien plants. They are prioritized in most alien-plant management initiatives in South Africa. The current practice for the restoration of cleared riparian areas relies largely on the unaided recovery of native species from residual individuals and regeneration from soil-stored seed banks. Little is known about the factors that determine the effectiveness of this approach. We need to know how seed banks of native species in riparian ecosystems are affected by invasion, and the potential for cleared riparian areas to recover unaided after clearing operations. Study sites were selected on four river systems in the Western Cape: the Berg, Eerste, Molenaars and Wit Rivers. Plots were selected in both invaded (> 75% Invasive Alien Plant (IAP) canopy cover) and un-invaded (also termed reference, with < 25% IAP canopy cover) sections of the rivers. Replicate plots were established at two elevations (mountain stream and foothill) and in three moisture regimes (dry, wet and transitional bank zones). Soil samples were taken, surveys were done of the aboveground vegetation, and comparisons were made between invaded and non-invaded sites. Seed bank communities were clearly defined by the state of the river (reference or invaded) and moisture regimes (wet and dry bank zones). Comparisons at a landscape scale showed no clear pattern, as the composition of both aboveground and seed bank species assemblages were strongly influenced by site history, especially the extent of invasion and fire frequency. Even after heavy and extensive invasion, riparian seed banks have the potential to initiate the restoration process. However, not all riparian species are represented in the seed bank. Based on these results, restoration recommendations are outlined for alien-invaded riparian zones.
 
Antibacterial activity of screened plant extracts.
Anti-candidal activity (MIC and MFC) of screened plant extracts.
Number of H + colonies in Salmonella typhimurium strain T98 produced by antimicrobial crude extracts.
Article
Petroleum ether, dichloromethane, ethanol (70%) and water extracts of 12 South African plants were screened using microdilution assays against Gram-positive (Bacillus subtilis, Staphylococcus aureus), Gram-negative (Escherichia coli) bacteria, and the fungus Candida albicans. No antimicrobial activity was observed in water extracts. The ethanol extracts of Becium obovatum leaves showed the best antibacterial activity with a minimum inhibitory concentration value of 0.074 mg/ml against B. subtilis. The petroleum ether extract of leaves of Cucumis hirsutus, Haworthia limifolia and Protea simplex showed good antibacterial activity with MIC values ranging between 0.098 and 0.780 mg/ml against all the test bacteria. The petroleum ether extract of P. simplex leaves showed the best anti-candidal activity with a minimum fungicidal concentration value of 0.014 mg/ml. The ethanol extracts of Agapanthus campanulatus (leaves and root), Dissotis princeps and Gladiolus dalenii as well as the dichloromethane extract of P. simplex leaves showed good anti-candidal activity with minimum fungicidal concentration values ranging between 0.037 and 0.39 mg/ml. Mutagenicity tests conducted on extracts that showed good antimicrobial activity suggest the plants are probably safe for consumption. The results obtained in this study show that some of the traditional plants may indeed be effective for the treatment of ailments related to gastro-intestinal disorders that may be due to the test pathogens.
 
Article
Recovery of indigenous species subsequent to the clearing of invasive alien plants (IAPs) is crucial for ecosystem recovery to occur. However, cleared sites are often just left in the hope that revegetation will occur naturally. In riparian areas of Kruger National Park (KNP), the Working for Water (WfW) Programme has cleared IAPs on a regular basis, but little post-clearance monitoring has taken place. Thus investigating short-term effects of IAPs and IAP clearing on plant community diversity and vegetation recovery provided an ideal opportunity to assess feasible targets of natural ecosystem recovery in similar areas. Vegetation was sampled from twelve transects along the Sabie River in and adjacent to the KNP, before (March/April 2006) and after (March 2007) the annual clearing of IAPs by WfW. Rarefied species richness, alpha diversity and evenness of distribution of species all declined with increasing density of IAPs (P < 0.05). There was a mean reduction in IAP density of 80% (S.E ± 6%) (P = 0.002) through the clearing by WfW. After clearing of IAPs, indigenous vegetation densities increased, with herbaceous growth forms showing the largest increase in transects that were previously heavily invaded. Thus, in this system, which is relatively undisturbed by human activities, initial recovery of indigenous vegetation can occur without further restorative interventions. This process is more than likely aided by the continuous clearing of IAPs by WfW as this acts to deplete alien seed banks and maintain IAPs at acceptable and manageable levels.
 
Article
For southern Africa, patterns of bee diversity and endemism were studied with a special focus on South Africa and the Cape Floral Kingdom. Based on distribution records of 645 species incorporated in the “Southern African Bee Database” (SouthABees), the pattern of bee diversity was analysed on a 2° × 2° grid. The resulting map shows a bicentric pattern, with highest species diversity located in the arid west and in the relatively moist east. The investigation of distribution patterns of 516 South African species identified twelve distribution types that largely coincide with patterns in the seasonality of precipitation: winter rainfall, early to mid summer rainfall, late to very late summer rainfall and rain all year. The largest number of bee species is associated with the winter rainfall area (46.3% of the fauna) and with the early to mid summer rainfall area (36.5% of the fauna). Consequently South Africa is a centre of bee diversity of global significance. The most important centres of endemism are the winter rainfall area in the west (27.3% of total fauna endemic) and the early to mid summer rainfall area (29.1% of total fauna endemic) in the east. The relationship between bee/plant diversity patterns and speciation is discussed.
 
Pterygodium vermiferum . (A) bud-like, partially open flower, lateral view; (B) the same, adaxial view; (C) fully open flower, adaxial view; (D) the same, lateral view; (E) posterior sepal, adaxial view; (F) right-hand lateral petal, adaxial view; (G) apex of lip appendage, lateral view; (H) gynostemium, half abaxial view. Hatching = attachment of removed median sepal and lateral petal. Scale bar = 4 mm. All drawn from the type collection by E.G.H. Oliver. 
Pterygodium vermiferum . (A) whole plant, the basal leaf is shrivelled and flat on the ground, the flowers mostly post-pollination; (B) top of an inflorescence showing fully open flowers and, bottom left, a partially open flower; top left-hand fully open flower with deeply Y-shaped central lip appendage, the bottom right-hand flower with a shallowly emarginate appendage ( Oliver et al., 12402 ). Photographs by E.G.H. Oliver; (C) inflorescence from the Die Kelders population. Photograph by H. Stärker; (D) close-up of flowers from the upper Swartkransberg population, 2005; (E) inflorescence from this population in 2006 in late flowering stage. Photographs by H. Lutzeyer. 
Pterygodium volucris . Close-up of flower. Photograph by W. Liltved. 
Known distribution of Pterygodium vermiferum . 
Article
Pterygodium vermiferum, a new orchid belonging to the subtribe Coryciinae, is described from the coastal region in the southwestern part of the Cape Floristic Region, South Africa. It is most similar to Pterygodium volucris (L.f.) Sw. and differs most obviously in the possession of several remarkable long twisted appendages arising from the rostellum and in having a cucullate rather than tubular galea. The flowers open very briefly before wilting and setting seed by autonomous self-pollination. The morphological autapomorphies that define the species are interpreted as adaptations for autonomous self-pollination in a clade that is ancestrally pollinated by oil-collecting Rediviva bees. The description of P. vermiferum requires that another pollination independent Pterygodium taxon (P. newdigateae Bolus var. cleistogamum Bolus) also be awarded species status.
 
6 ′ -Malonylnataloin from Aloe ellenbeckii (anthrone core numbered according to IUPAC). 
NMR spectral data for 6′-malonylnataloin (1) (CD 3 OD, 30 °C, δ in ppm, J in Hz)
Article
6′-Malonylnataloin, a malonylated derivative of the rare anthrone nataloin, is characterised for the first time from Aloe ellenbeckii A. Berger. Anthrone C-glycosides are among a suite of chemical constituents of systematic importance in Aloe. The compound is of interest as a putative phytochemical marker for the east African taxa in the maculate species complex.
 
Article
Satyrium situsanguinum is described as a new species from the Slanghoek Mountains of the southwestern part of the Cape Floristic Region, South Africa. It is recognised by the urceolate-campanulate cauline, leaf sheaths, and white flowers with spurs longer than the ovary.
 
Location of the study area. 
Article
A vegetation survey of natural grasslands was undertaken in the urban areas of Gauteng, supporting about 20% of the country's population. Releves were compiled in 132 sample plots placed in selected open spaces in the study area. A floristic-sociological classification revealed eight grassland communities, represented by 59 releves. A hierarchical classification, description and ecological interpretation of these plant communities are presented. (c) 2006 SAAB. Published by Elsevier B.V. All rights reserved.
 
Number of His + revertants in Salmonella typhimurium strain TA98 produced by crude plant extracts
activity (MIC) of plant extracts (mg/ml) used in South African ethnoveterinary medicine as determined using the micro-dilution assay
Article
Crude dichloromethane and 90% methanolic extracts of plants used traditionally in the treatment of wounds and retained placenta were screened for their antibacterial, anti-inflammatory (cyclooxygenase-1 and-2) activities and investigated for potential mutagenic effects. Antibacterial activity was evaluated using the micro-dilution assay. The bacterial strains used were Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). DCM extracts of Dicerocaryum eriocarpum, Pterocarpus angolensis, Ricinus communis and Schkuhria pinnata exhibited the highest antibacterial activity. In the anti-inflammatory assay, dichloromethane extracts of stems of Cissus quadrangularis and roots of Jatropha zeyheri showed selective inhibition of COX-2 (75% and 77%), while dichloromethane extracts of the shoots of S. pinnata showed selective inhibition of COX-1. None of the plant extracts were mutagenic in the Salmonella typhimurium Ames test (strain TA98). The results suggest that most plants used traditionally for treating wounds and retained placenta in animals are effective in combating infection and reduction of pain. Lack of mutagenicity suggests that these plants are probably safe for use.
 
Selected commercial herbal mixtures sold in KwaZulu-Natal, South Africa.
50 values (mg/mL) after 24 h treatment of HepG2 with herbal test mixtures.
Article
Cytotoxic and mutagenic effects of thirteen commercial herbal mixtures sold in KwaZulu-Natal, South Africa were evaluated using the neutral red uptake (NRU) assay and the Ames test. The herbal mixtures tested included Umzimba omubi, Umuthi wekukhwehlela ne zilonda, Mvusa ukunzi, Umpatisa inkosi, Imbiza ephuzwato, Vusa umzimba, Ingwe® muthi mixture, Ibhubezi™, Supreme one hundred™, Sejeso herbal mixture Ingwe®, Lion izifozonke Ingwe®, Stameta™ BODicare® and Ingwe® special muti. The relative cytotoxicity of the herbal mixtures was established by determining their NI50 values (50% inhibition of neutral red uptake). The test revealed that the most toxic herbal mixture was Umpatisa inkosi with an NI50 value of 0.016 mg/mL and the least toxic mixture was Stameta™ BODicare® with an NI50 value of 28.00 mg/mL. The herbal mixtures showed no mutagenic effects against Salmonella typhimurium tester strains TA98, TA100, TA102, TA1535 and TA1537 when the assay was done without S9 metabolic activation. However, four herbal mixtures, Umpatisa inkosi, Imbiza ephuzwato, Vusa umzimba and Stameta™ BODicare® showed mutagenic effects against TA98 but not the rest of the tester strains after using S9 metabolic activation. Umpatisa inkosi also exhibited weak mutagenic activity against TA1535 after metabolic activation. The remaining mixtures did not show mutagenic effects against all the tester strains after S9 metabolic activation. The cytotoxic and mutagenic results reported here offer a step toward determining the safety of commercial herbal mixtures in South Africa. Herbal mixtures showing higher cytotoxic and mutagenic effects need to be further investigated for their possible effects on humans.
 
Article
Lycium hantamense, a new species is described. This species was discovered in the Hantam–Roggeveld Centre of Plant Endemism of the Succulent Karoo Region, South Africa. L. hantamense belongs to a unique group of seven polyploid, functionally dioecious species in a genus of normally diploid, hermaphrodite species. This new species resembles L. strandveldense most closely.
 
Bulbous medicinal plants used in this study. 
Article
The growing popularity of traditional medicine and the unrestricted collection of medicinal plants from the wild have put many of the slow growing bulbous plant species at the risk of over-exploitation and extinction in South Africa. This study was aimed at comparing the phytochemical composition and biological (antibacterial and anticandidal) activities of bulb and leaf extracts of Tulbaghia violacea, Hypoxis hemerocallidea, Drimia robusta and Merwilla plumbea between spring, summer, autumn and winter seasons, with the view of promoting the use of leaves, as a conservation strategy. Antibacterial and anticandidal activities of petroleum ether (PE), dichloromethane (DCM), 80% ethanol and water extracts of bulbs and leaves were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae bacteria and the fungus Candida albicans using the microdilution bioassay. Spectrophotometric methods were used to evaluate saponin and phenolic compositions for the four seasons. Leaf and bulb extracts exhibited comparable anticandidal activity (MIC < 1 mg/ml) in all the plant species in all seasons. Only ethanol and water extracts of H. hemerocallidea corms (autumn and winter) showed correspondingly good fungicidal activity amongst the bulbs tested. Antibacterial activity was fairly comparable between bulbs and leaves with at least one extract of each plant species showing some good MIC values in most of the seasons. The best antimicrobial activities were recorded in winter and autumn seasons, with MIC values as low as 0.2 mg/ml in the DCM bulb extracts of T. violacea (winter) against K. pneumoniae and S. aureus. The amounts of total phenolic compounds in all plant samples were generally higher in spring compared to the other seasons. Condensed tannin, gallotannin and flavonoid levels, depending on the sample, were either higher in spring or winter except for H. hemerocallidea (corm) which had higher gallotannin levels in autumn. Total saponin levels were higher in winter in all plant samples. Although variation was observed in the phytochemical concentrations between the bulbs and leaves of each plant species, their antimicrobial activities were fairly comparable. Leaves may be used as substitutes for bulbs in the treatment of bacterial and fungal ailments.Research Highlights► Antibacterial and antifungal activities were comparable in bulbs and leaves. ► Phytochemical contents varied between leaves and bulbs of medicinal plants. ► Phytochemical compounds were higher in spring and winter than in other seasons.
 
Article
The rhizospheres of cassava (Manihot esculenta) plants growing in Limpopo and Mpumulanga provinces in South Africa were sampled for the presence of arbuscular mycorrhizal fungi (AMF). The two provinces corresponded to high input commercial and low input subsistence agricultural soils, respectively. The Limpopo soils yielded Acaulospora scrobiculata, Glomus rubiforme and Gigaspora sp.1 whereas the Mpumulanga soils yielded Acaulospora scrobiculata, Acaulospora mellea, Acaulospora tuberculata, Glomus etunicatum, Glomus rubiforme, Gigaspora sp. 2 and Scutellospora sp., a total of eight species. The higher diversity in the Mpumulanga sites corresponded with lower soil nitrogen and total and available phosphorus levels. Descriptions of the species are given and the results are discussed in relation to AMF diversity found in other parts of Africa.
 
Article
Struthiola ciliata (L.) Lam., an ericoid shrub widespread in fynbos vegetation in the southwestern Cape, displays the floral syndrome associated with pollination by settling moths. Flowers, which are produced throughout the year, are creamy white in colour, with a slender hypanthium tube ± 20 mm long. The anthers are included within the tube and the mouth of the tube is surrounded by eight fleshy petaloid scales. Anthesis takes place in the evening at ± 18h00, at which time the flowers begin to emit a strong, sweet, spicy and somewhat coniferous fragrance from the petaloid scales. The compounds thujone, isothujone, verbenone, α-terpineol, benzyl acetate, eugenol and vanilline are the main components of the scent profile detectable by the human nose. The cells of the petaloid scales are densely cytoplasmic and contain numerous oil droplets. Starch-rich tissue is located near the mouth of the hypanthium tube. Flowers accumulate small volumes (0.025–0.188 μl) of moderately concentrated nectar (20–34% sucrose equivalents) in the hypanthium tube. Individual flowers last for 9 to 11 days, with nectar secretion restricted to the first 3 to 4 days. The only floral visitors observed were the moths Syngrapha circumflexa (Linnaeus) and Cucullia terensis (Felder and Rogenhofer) (Lepidoptera: Noctuidae), which visited the flowers at dusk and early evening, confirming that the species is moth-pollinated.
 
Sclerocarya birrea populations sampled from seven countries in Africa for an assessment of genetic variation: (a) Geographic distribution of sampling localities. Populations of subspecies caffra (1 to 12) formed the main body of this study. However, additional populations, of subsp. birrea and subsp. multifoliolata (13 to 15, area enclosed by darker shading), were sampled for an assessment of subspecies variation in Tanzania (see Table 1 for further information); (b) Distribution of four chloroplast haplotypes revealed at the intergenic spacer between the trnT (UGU) and the trnL (UAA) 5′ exon. Pie diagrams indicate the proportion of types at each site. 
Principal coordinate analysis of RAPD phenotypes for Tanzanian individuals (N = 29) of three subspecies of Sclerocarya birrea. Subspecies designations (birrea, caffra and multifoliolata) are shown. In addition, individuals are labelled by chloroplast haplotype assigned by PCR-RFLP analysis (haplotypes R, U and T present in Tanzania). 
birrea leaf samples from seven countries in Africa for an assessment of genetic variation 
Article
Indigenous fruit trees are widely used by humans in southern Africa. Little information is however available on regional genetic variation in these species, knowledge essential for their proper use and conservation. Here, we begin to address this gap by assessing RAPD and chloroplast variation in Sclerocarya birrea, a fruit tree that has been important to humans in the region for millennia. A strong overall positive correlation between genetic (RAPD) and geographic distances was observed for 12 populations of S. birrea subsp. caffra sampled from seven countries (standardised Mantel statistic, rM = 0.857, P < 0.001), supporting a ‘structuring-by-distance’ model in devising genetic management strategies. Cluster analysis indicated, however, that genetic distances between geographically proximate stands were high on occasions, suggesting that inclusion of multiple stands nationally can sometimes be useful in rangewide management. Overall, an analysis of molecular variance (AMOVA) indicated that 19% of RAPD (assumed nuclear) variation partitioned among S. birrea subsp. caffra stands. Consistent with other nuclear–organellar comparisons for tree species, a much greater proportion of chloroplast variation (70%) partitioned among stands, suggesting a rather limited role for seed compared to pollen in mediating gene flow. Further analysis of S. birrea involved additional sampling from Tanzania of two other recognised subspecies (subsp. birrea and subsp. multifoliolata) that are not otherwise found in the southern Africa region. AMOVA indicated that more RAPD (29%) and chloroplast (75%) variation partitioned among relatively proximate subspecies stands (4 populations, 1 subsp. caffra, 2 subsp. birrea and 1 subsp. multifoliolata) in Tanzania than among subsp. caffra stands sampled extensively across southern Africa, suggesting Tanzania should be a focus for genetic management activities.
 
Article
An analysis of the size class distribution structure of the Tall and Short Sand Forest subcommunities of the Tshanini Game Reserve is presented for the first time. The study area lies south of Tembe Elephant Park within the Maputaland–Pondoland–Albany biodiversity hotspot of South Africa. A preliminary survey for distribution and abundance of hardwood tree species was conducted in both Tall and Short Sand Forest subcommunities. The data on the size class distribution were analysed at both subcommunity and species levels to classify the population structure. The population structure indicated that at the subcommunity level, the Short and Tall Sand Forest have growing populations of species, and are forests of coarse to intermediate grain respectively. At species level, four categories were distinguished, ranging in scale from an ideal to an abnormal size class distribution of the population. Most evaluated forest species indicated a growing or stable population structure. A range of species was evaluated for potential sustainable utilisation.
 
Comparison of median number of seeds per capsule (2007) between unmanipulated Brunsvigia litoralis flowers in the urban and rural populations (Z = 2.50, p = 0.01, Mann–Whitney U-Test). Numbers above bars = number of plants.  
Article
The impacts of habitat fragmentation and reduced population sizes on ecological processes deserve more attention. In this study we examine pollination in rural and urban populations of Brunsvigia litoralis (Amaryllidaceae), an endangered endemic and a flagship species for plant conservation in South Africa. B. litoralis has flowers conforming to the bird-pollination syndrome, but the only flower visitor at the urban sites, the Greater Double-collared Sunbird (Cinnyris afra) (1.6 visits/flower/hour), is unable to access the nectar in the usual way due to a long perianth tube (38.8 mm) and resorts to robbing. Supplemental hand pollination was used to test for pollen limitation of seed set at the urban sites flowers were pollen-supplemented. Seed set in supplemented plants increased by more than an order of magnitude relative to controls. The longer-billed Malachite Sunbird (Nectarinia famosa) was observed as the sole pollinator of B. litoralis at the rural site where seed set was significantly higher. Although B. litoralis plants are long lived, the absence of pollinators in these urban fragments might place populations at an extinction risk.Research highlights► Brunsvigia litoralis is specialized for pollination by the Malachite Sunbird, Nectarinia famosa. ► Shorter-billed Greater Double-collared Sunbird, Cinnyris afra, obtained nectar through robbing. ► Low seed set in small, urban, Malachite Sunbird absent populations.
 
Article
An AMF infectivity study and spore viability assessment was performed on substrata obtained from gold and uranium mine tailings dumps (‘slimes dams’) in the North West and Free State provinces of South Africa. Three slimes dams in each region were categorized as recently vegetated (RV), old vegetated (OV) and never vegetated (NV), and dams then divided into five zones based on elevation above ground level, steepness and broad chemical differences. Rhizosphere samples were collected from two of three plant species common to all sites; Eragrostis curvula, Atriplex semibaccata and Cynodon dactylon, as well as from bare areas, in order to allow comparisons across all site categories because of the rarity of the grasses on the lower slope of NV dams. Infectivity was determined by the mean infection percentage method from a bioassay of the substrata using Eragrostis curvula cv Ermelo as a host plant. There was no difference in total infectivity between North West and Free State substrata, but within regions, there were differences in infectivity between rehabilitation ages, between zones, and between rhizosphere and bare areas. Toepaddock substrata and veld soil produced the highest total infection levels overall. On both dams and veld, total arbuscular levels differed between rhizosphere and bare substrata, and the percentage of arbuscules (max. 15.4%) and vesicles (max. 22.0%) as a proportion of total infection structures was low. A low correlation between infectivity and total spore numbers was also found. Spore numbers and the numbers of viable spores increased with zone down the slimes dams to the veld, and also differed within zones between rhizosphere and bare substrata with marked interactive effects. Substratum organic matter (SOM) levels differed between regions, and between zones within the North West region increasing with distance down the slopes to the veld, and were strongly correlated with total spore numbers. Substratum pH values and most AMF parameters were positively correlated in the order of RV > OV > NV dams, indicating that natural colonization of acidic NV sites by AMF is at very low rates, and that AMF colonizing RV slopes are not surviving the transition from RV to OV, with the associated increase in acidity, conductivity and decline in plant cover. Substratum conductivity differed between zones in both regions, with minor interaction between region and zone, and was negatively correlated with pH, AMF infectivity and total spore numbers. Our findings demonstrate that the ameliorant effects of liming and irrigation on substratum pH and conductivity are short-lived, but despite the physico-chemical constraints, a significant measurable AMF inoculum potential does exist on all substrata. Amelioration of tailings with organic matter and use of acid and salt-tolerant AMF would be expected to contribute to more persistent AMF communities and vegetation on gold and uranium slimes dams.
 
The study site and representative grassland species: a) grassland vegetation on the summit of Mt Gilboa; b), Megachile bee on Eriosema distinctum; c). Honeybee foraging for nectar on Moraea inclinata; d) Solitary bee Amegilla natalensis on Disa versicolor; e) Hemipepsis wasp on Pachycarpus grandiflorus; f) Tabanid fly Philoliche aethiopica on Watsonia lepida; g) Butterfly Aeropetes tulbaghia on Kniphofia laxiflora; h) Hawkmoth Basiothia schenki on Satyrium longicauda; i) Aloe boylei, a sunbird-pollinated species. Photos: a, c–f, h, i — S.D. Johnson; b, g — L.F. Harris.  
Most investigated South African grassland flowers are dependent on pollinators for fertilization (either self-incompatible, or self compatible, but incapable of autonomous pollination).
Summaries of the pollination systems of the twenty-one study species with details of study sites used and time spent observing the species.
Article
Southern African grasslands harbour diverse plant communities, and recent studies have revealed remarkable plant–pollinator interactions in this biome. However, there has been no attempt to study community-wide patterns in breeding systems or plant–pollinator mutualisms. Here, we present the results of extensive field work on twenty-one wildflower species with large, showy flowers, belonging to a broad range of angiosperm families. Most of the plant species investigated were found to be self-incompatible and therefore completely dependent on pollinators. Based on over 250 h of field observations during which we recorded over 1000 individual insects, 368 of which were examined for pollen loads, we identified pollination systems involving, inter alia, bees and flies (both short- and long-tongued), wasps, butterflies, hawkmoths, beetles, and sunbirds. The most important pollinators of the wildflowers investigated in the community were long-tongued solitary bees. Several plant species appear to be dependent on a single or a few pollinator species, and few are true generalists. This high degree of specialisation indicates a well-structured pollination landscape, suggesting both a history of climatic and ecological stability and potential sensitivity to human disturbance.
 
Article
There is increasing evidence that nectarivorous yeasts are an important third player in plant–pollinator mutualisms, but their distribution and ecological effects remain poorly known. Here we provide a survey of the frequency and abundance of yeasts in floral nectar from 40 taxonomically diverse South African plant species, test whether they affect nectar properties, and investigate associations between yeast incidence and pollinator type. Microscopical observations of nectar samples revealed that yeasts are widespread in floral nectar of South African species, as revealed by the high percentage of plants (51.3%) and flowers (43.2%) containing those microbes, and that when present, they can reach high densities (up to 3.6 × 106 yeast cells/mm3 in Moraea graminicola). Further, a significant negative correlation was found between yeast density and sugar content (Rs = − 0.463, P = 0.039) and yeast density and nectar concentration (Rs = − 0.470, P = 0.037) in a Watsonia species. Interestingly, variation in yeast incidence among plant species was related to differences in pollinator type, in such a way that the plant species pollinated by birds showed the highest proportion of plants and flowers with yeasts, while those visited only by Hymenoptera showed the lowest values. Our study confirms the ubiquity of nectarivorous yeasts in plant communities and identifies novel ways of approaching the study of nectar characteristics and exciting new perspectives on the role of yeasts in plant–pollinator relationships.
 
Article
Oxalis section Sagittatae (Oxalidaceae) is distinguished from other South African members of the genus by their diverging two lower reproductive organ levels. Here we investigate the floral morphology and reproductive strategy of members of Oxalis section Sagittatae. Flowers of two Sagittatae species, from seven populations, were compared in terms of corolla and reproductive organ morphology, reproductive organ level segregation and reproductive organ spatial arrangement. Self-incompatibility expression was also tested through crossing experiments in three of these populations. In members of Oxalis section Sagittatae sexual reproductive organs are arranged by height, angle of flexure from the central floral axis and by the orientation of the anthers and stigmas. This represents a tristylous form of three-dimensional reciprocity, a distylous form of which was recently described in Linum suffruticosum. Members of Oxalis section Sagittatae present self-compatibility, rendering the system more reliant on reciprocity. A consistent and precise pattern of flower visitation by pollinators is thus required in this Oxalis system to achieve out-crossing. Deviations in this visitation pattern can result in seed set through selfing.Highlights► A new variation of stylar polymorphism, three-dimentional tristyly, is described in the Oxalidaceae. ► This is the only case of this system known among angiosperms. ► Section Sagittatae is distinguished from other South African members of Oxalis (Oxalidaceae). ► The morphological and reproductive expression of this system is presented.
 
Article
Pollination systems in orchids tend to be specialized as a consequence of restrictive floral morphology and specific advertising signals. Here we document a notable exception: Disa fragrans subsp. fragrans, a taxon from the Drakensberg Mountains of South Africa, which is pollinated by insects belonging to at least four orders (flies, beetles, bees, and moths). Pollinaria of D. fragrans are attached to the feet of these visitors and pollination thus occurs in a rather haphazard fashion. Nevertheless, its pollination success and pollen transfer efficiency are comparable to those of its close relative, Disa sankeyi, which is pollinated by a single genus of wasps. D. fragrans has an exceptionally strong floral scent: volatile emission is 19–86 μg per inflorescence per hour, which is up to 100 fold greater than in D. sankeyi. The scent bouquet is comprised of at least 46 compounds, mostly benzenoids and phenylpropanoids, which are known to be general attractants to a wide range of insects. In contrast to D. sankeyi, the flowers of D. fragrans have a high level of spectral purity (chroma) as is typical of many generalist insect-pollinated plants. At a site where D. fragrans co-occurs with D. sankeyi we found a plant with intermediate characteristics that may be a hybrid between the two taxa. The novel case of generalist pollination in D. fragrans documented here serves as an example of how floral advertising traits might evolve during an evolutionary shift from specialized to generalized pollination.
 
Article
Leaf extracts of seven South African plant species with minimal inhibitory concentrations of 0.1 mg/ml and below against Candida albicans based on a preliminary screening were evaluated for antibacterial and antifungal activities using microplate dilution method and bioautography. Aspergillus fumigatus, Micrococcus canis, C. albicans, Sporothrix schenckii and Cryptococcus neoformans were the fungal test organisms, while the bacterial species used were Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa. The plant species investigated were Cussonia zuluensis, Vepris reflexa, Curtisia dentata, Trichilia emetica, Terminalia phanerophlebia, Terminalia sambesiaca and Kigelia africana. Plant material was extracted with n-hexane, dichloromethane and acetone. The acetone and dichloromethane extracts of all plant leaves were active against some or all of the tested microorganisms. Extracts of C. dentata, T. sambesiaca and T. phanerophlebia had the highest activities against both bacterial and fungal test organisms with minimal inhibitory concentration (MIC) values as low as 0.02 mg/ml. C. zuluensis was the least active with relatively high MIC values and only one band on TLC plates active against C. albicans. The highest number (5) of active bands against C. albicans on bioautograms was observed in the acetone extracts of C. dentata. C. dentata extracts also had five compounds active against other tested fungal and bacterial species. Compounds with similar Rf values in this extract were active against both bacterial and fungal test organisms, suggesting that the microbial growth inhibitory activity of C. dentata extracts was non-selective. C. dentata was selected to isolate compounds active against C. albicans.
 
Article
A number of rust fungi are recorded from southern Africa for the first time. Aecidium nairobianum is newly recorded from South Africa and Zimbabwe, and transferred to the genus Endophyllum as Endophyllum nairobianum comb. nov. Pucciniosira anthocleistae and Ravenelia ornata are also newly recorded from South Africa. Uredo abri is reduced to a synonym of R. ornata. Also, new details on the life cycle of several species have been elucidated from recent collections. The full life cycle of both Puccinia phyllocladiae and Uromyces kentaniensis are described. Aecidium capense is reduced to a synonym of the former and Aecidium antholyzae of the latter. Uromyces ventosa is reduced to a synonym of the microcyclic Uromyces bolusii. The taxonomic status of several species of rust fungi (Uredinales), recorded from southern Africa, requires changing to accommodate revised generic concepts. The following new combinations are made: Diorchidium gerstneri (Doidge) A.R. Wood comb. nov., Phakopsora nyasalandica (Cummins) A.R. Wood comb. nov., and Uredo doidgeae (Syd. and P. Syd.) A.R. Wood comb. nov. Schroeteriaster stratosus is confirmed as a synonym of Phakopsora stratosa. Melampsora junodii Doidge is reduced to a synonym of Phakopsora vernoniae Jørstad, and Uromyces paradoxus Syd. and P. Syd. is reduced to a synonym of Uredo balsamodendri Cooke. Details of the holotype of Puccinia estcourtensis Gjærum were omitted from the original description. These are supplied here, validating this species as Puccinia estcourtensis Gjærum ex A.R. Wood and Gjærum, sp. nov.
 
Article
The antifungal activities of acetone, hexane, dichloromethane and methanol leaf extracts of 24 South African Combretum species were determined against five fungal animal pathogens (Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Microsporum canis and Sporothrix schenckii) representing yeasts, moulds and dimorphic fungi. MIC's determined after 48 h were usually two times higher than values determined after 24 h. Most of the antifungal extracts had MIC values of c. 0.08 mg/ml, some with MIC values as low as 0.02 mg/ml. These are substantially better values that reported in the literature to date. M. canis was the most susceptible microorganism followed by S. schenckii. A. fumigatus was the most resistant of the pathogens tested. Methanol extracted the highest quantity from leaves, but the acetone extracts had the highest antifungal activity in practically all cases. The methanolic extracts of C. moggii and C. petrophilum were however most active against all the pathogens. All extracts of C. nelsonii were also very effective against all the pathogens. Based on these results and work done earlier, C. nelsonii was selected for fractionation and bioassay-guided isolation of the antifungal compounds followed by C. albopuntactum, and C. imberbe.
 
Top-cited authors
B.-E. Van Wyk
  • University of Johannesburg
Alvaro Viljoen
  • Tshwane University of Technology
Anna K Jäger
Jacobus Nicolaas Eloff
  • University of Pretoria
Sandy Van vuuren
  • University of the Witwatersrand