Thesis (doctoral)--Universität Breslau, 1900. / "Arbeit aus dem Königl. Botan. Garten der Universität Breslau." Lebenslauf. Includes bibliographical references.

M.Sc., Faculty of Science, University of the Witwatersrand, 2011 / Pelargonium sidoides has been used for centuries in traditional medicine in Lesotho and South Africa as well as globally in modern medicine. Consequently P. sidoides tubers have been wild-harvested extensively in Eastern Cape and Lesotho to meet the growing trade demand. In recent years, the number of plant gatherers intending to supply markets and generate incomes have increased. Tubers are targeted because they contain medicinal properties. The medicinal compounds in the tubers are thought to be highly correlated with colour, with their concentration increasing as the colour develops towards dark-red. Dark-red coloured tubers seem to be preferred by the Pelargonium industry and are considered to be mature. Repeated harvesting of P. sidoides plants from the wild has been reported to result in localized population declines. This is exercabated by harvesting methods currently used which involve entire removal of the plant and not filling up harvest holes to safeguard tuber remnants left in the soil. Although various studies have investigated the impacts of such harvesting operations on P. sidoides wild populations, these studies have not provided information on tuber recovery rate and suitable recommendations to ensure sustainable harvest of P. sidoides from the wild. Therefore this study investigated (i) rate of tuber recovery in P. sidoides plants, (ii) impacts of wild harvest on its tuber recovery and (iii) made recommendations on sustainable harvest options for the species. The investigations were made using linear and non-linear regression models and ANOVA. Comparisons were done for “lowveld” (Eastern Cape) and “highveld” (Lesotho and Free-State) vegetation regions. The rate of P. sidoides tuber recovery was measured by tuber recovery colour and biomass in previously wild-harvested sites. Tuber regrowth rate in cultivated sites was also investigated in the same manner to determine prospects for cultivation. Time since last harvest was found to affect tuber recovery colour and biomass. As time since last harvest increased in the “lowveld” and “highveld” vegetation regions, tuber recovery colour and biomass also increased (lowveld- r2= 0.63, P < 0.05, d.f = 7 and highveld- r2= 0.55, P < 0.05, d.f = 5). In cultivated sites, only tuber regrowth using biomass was found to increase positively with time when study sites from the “lowveld” and “highveld” vegetation regions were combined (r2= 0.68, P < 0.03, d.f = 8). P. sidoides tuber recovery size was found to be smaller in previously wild-harvested sites compared to tuber size in unharvested control sites in the “lowveld” and “highveld” vegetation regions (lowveld- F11,95= 9.7226, P < 0.001, highveld- F23,99= 7.0519, P < 0.001). Cultivated plants also had more tuber regrowth size than tuber recovery size of previously wild-harvested sites showing that cultivation can be a viable option to produce the resource and contribute to the conservation of the wild resource. ii To ascertain under which scenarios P. sidoides can be harvested sustainably in the wild, factors which affect sustainable harvesting of P. sidoides such as effects of depth of harvest hole, mother tuber size (biomass), canopy area and altitude on tuber recovery biomass, tuber recovery colour and number of stems/plant were explored. Although results that were obtained varied, filling harvest holes with soil post-harvest increased tuber recovery biomass meaning that this factor can be included in P. sidoides harvesting guidelines. Furthermore, tuber and tuber recovery biomass tended to increase with an increase in canopy area suggesting that canopy size can be used as a surrogate for tuber size (tuber recovery biomass r2= 0.81, P < 0.05, df = 7, tuber biomass- r2= 0.57, P < 0.05, df = 7). The findings of this study revealed that tuber recovery colour and biomass in previously wild-harvested sites increased positively with time. P. sidoides plants were found to require ≥8 years for tuber recovery to develop the dark-red colouration and ≥10-15 years for previously wild-harvested plants to reach pre-harvest biomass. Furthermore, tuber recovery size in previously wild-harvested sites was found to be smaller compared to tuber size in unharvested sites even after 8 years since last harvest suggesting that tuber recovery size has not reached pre-harvest size after this period. Hence this confirms that even a single return harvest event within a 10 to 15 post harvest period can negatively affect wild populations of P. sidoides. This period is however too long for a sustainable Pelargonium industry thus questioning wild harvest as a viable methodology without rigorous ongoing monitoring and management of wild harvest sites. This is despite training on sustainable harvest, such as harvest methods provided by the Pelargonium industry. Conversely, prospects for cultivation as a viable alternative to wild harvest seem promising since cultivated plants only required ≥9 years to attain similar biomass to that of unharvested wild plants. Given that it is unclear what the Pelargonium industry considers as commercially acceptable for P. sidoides tuber characteristics, the tuber regrowth rate of ≥8years in cultivation may be shortened to meet trade specifications. The study also showed that for sustainable wild harvest of P. sidoides, harvest operations should entail effective closure of harvest holes with soil to ensure the survival of tuber remnants. Additionally, plants with bigger canopies may be targeted when harvesting P. sidoides in previously wild-harvested and new harvest areas. It must be noted though that a thorough investigation is needed to ascertain whether canopy size can be confidently used as surrogate for tuber size. Therefore further research into sustainable harvest methods for P. sidoides is recommended, and direct longer term monitoring of selected sites would be useful. More research is also needed on tuber colour development in cultivated plants and what constitutes commercially harvestable tubers.

Thesis (PhD)--Stellenbosch University, 1994. / ENGLISH ABSTRACT: Fifty nine species were studied in this taxonomic treatment of section Hoarea (Sweet) DC. of the genus Pelargonium L'Herit., which was last revised by Knuth in 1912. The majority of species occur in the winter rainfall area of the south-western Cape, but some species occur in the eastern Cape, a region of winter and summer rainfall. A few species also occur in the summer rainfall area in the central Karoo. Morphological, leaf anatomical, palynological and geographical data were studied in order to delimit the taxa and to determine their relationships. Eight new species were described and several name changes were made. Diagnostic features of the section are the regularly or turnip-shaped tubers with numerous dark brown peeling tunics or periderms and apically a short flattened stem from which the leaves and scape emerge. The zygomorphic flowers are almost sessile, because the pedicels are very short (0,5--1 mm) and the hypanthia long (6--100 mm). A large variation occurs in leaf form and floral structure, and the section is divided in 14 different floral groups, mainly based on the structure of the androecium and the tectum of the pollen grains, although petal form and size are also considered in clustering the species. Section Hoarea with its deciduous geophytes and sometimes extremely zygomorphic flowers, exhibits advanced morphological characters. Because of the large variation in the structure of the androecium, pollination biology was probably one of the major driving forces in the evolution of the section, and the annual rainfall plays an important role in the distribution patterns of the different species. / AFRIKAANSE OPSOMMING: Neen en vyftig spesies is bestudeer in hierdie taksonomiese ondersoek van seksie Hoarea (Sweet) DC. van die genus Pelargonium L'Herit., wat laas deur Knuth (1912) hersien is. Die meerderheid van die spesies kom in die winterreenstreek van die suidwes Kaap voor, maar sommige spesies word ook in die Oos-Kaap, wat 'n winter- en somerreenstreek is, aangetref. Enkele spesies kom in die somerreenstreek van die sentrale Karoo voor. Morfologiese, blaaranatomiese, palinologiese en geografiese data is bestudeer om die verskillende taksons af te baken, en terselfdertyd verwantskappe tussen die onderskeie spesies te bepaal. Agt nuwe spesies is beskryf en verskeie naamsveranderinge is gemaak. Diagnostiese kenmerke van die seksie is die reelmatiggevormde of raapvormige wortelknol met verskeie afskilferende donkerbruin periderms en apikaal 'n verkorte stingel waaruit blare en 'n bloeispil groei. Die sigomorfe blomme is byna sittend, aangesien die blomstele uiters kort is (0,5--1 mm) en die hipantiums relatief lank (6-- 100 mm). 'n Groot variasie in blaarvorm en blomstruktuur kom voor, en die seksie word in 14 verskillende blomvorms verdeel. Hierdie blomvorms is hoofsaaklik gebaseer op die struktuur van die andresium en tektum van die stuifmeelkorrels, alhoewel kroonblaarvorm en -grootte ook 'n rol gespeel het in die onderverdeling van die seksie. Seksie Hoarea met sy bladwisselende geofiete en soms uiters sigomorfe blomme, vertoon gevorderde morfologiese kenmerke. Die groot variasie in die struktuur van die andresium dui op 'n moontlike prominente rol wat die bestuiwingsbiologie gespeel het in die evolusie van die seksie, en die jaarlikse reenval speel 'n belangrike rol in die verspreidingspatrone van die verskillende spesies.

No description available.

The plastid genomes of land plants are generally highly conserved in gene content and order, genome organization, and rates of sequence evolution; however, a few groups have experienced genomic change. The previously published sequence of Pelargonium X hortorum (Geraniaceae) reveals the largest, most rearranged plastid genome among land plants, and rate heterogeneity and genomic change have been documented in the monocot family Poaceae. Three initiatives were taken to characterize plastid genome evolution better in these groups. First, I estimate and compare genome-wide rates of sequence evolution in Geraniaceae genes relative to other angiosperms. An analysis of nucleotide substitutions for 72 plastid genes from 47 angiosperms, including nine Geraniaceae, shows that values of dN are accelerated in ribosomal protein and RNA polymerase genes. dN/dS, an indicator of selection, is significantly elevated in the same two classes of genes and ATPase genes. Second, I sequenced three additional Geraniaceae plastid genomes (Erodium texanum, Geranium palmatum, and Monsonia speciosa) and compare these sequences to each other, P. X hortorum, and other rosids. Geraniaceae plastid genomes are highly variable in size, gene content and order, and base composition. The genome of M. speciosa is among the smallest land plant plastid genomes, and one copy of the IR region in E. texanum has been lost. Gene/intron loss and gene duplication are rampant in Geraniaceae plastid genomes, and a number of losses are phylogenetically inconsistent. To explain the unusual rates and patterns of genome evolution in Geraniaceae, I propose a model of aberrant DNA repair coupled with altered gene expression. Lastly, I characterize genome evolution in the family Poaceae and order Poales. There has been a recent surge in the availability of Poaceae sequences, but a comprehensive analysis of genome evolution had not been performed that included any non-grass Poales taxa. I present the sequence of Typha latifolia (Typhaceae), the first non-grass Poales sequenced to date, and I show that Poaceae plastid genomes exhibit increased genomic rearrangements and nucleotide substitutions. These analyses show the extent of lineage-specific rate acceleration on the branch leading to Poaceae and deceleration during the diversification of the family. / text

Thesis (M.Sc. (Botany)) - Rhodes University, 2007.

The primary aims of this dissertation were to (1) identify and characterize the water-gap complex in seeds of Geraniaceae, (2) investigate its role in physical dormancy (PY) break and (3) develop a new classification system for water-gap complexes in seeds of angiosperms. The winter annuals Geranium carolinianum and G. dissectum were selected as the main representative species for the study, and seeds of an additional 29 species from the Geraniaceae were used to compare the water-gap complex within the family. A new classification system for water-gap complexes in species with PY was developed by comparing the morpho-anatomical features of PY seeds and fruits of 16 families. The water-gap complex of G. carolinianum was identified as a micropyle-hinged valve gap complex, and only a slight morpho-anatomical variation was observed within the family. Ontogenetic studies of the seed coat of G. carolinianum revealed that the water-gap region of Geraniaceae develops as an entity of the micropyle. The timing of seed germination with the onset of autumn can be explained by PY-breaking processes involving (a) two-temperature-dependent steps in G. carolinianum, and (b) one or two moisture-dependent step(s) along with the inability to germinate under high temperatures in G. dissectum. Step-I and step-II in PY-breaking of G. carolinianum are controlled by chemical and physical processes, respectively. This study indicates the feasibility of applying the developed thermal time model to predict or manipulate sensitivity induction in seeds with two-step PY-breaking processes. The model is the first and the most detailed one yet developed for sensitivity induction in PY-break. Based on the morpho-anatomical features, three basic water-gap complexes (types I, II and III) were identified in species with PY in 16 families. Depending on the number of openings involved in initial imbibition, the water-gap complexes were subdivided into simple and compound. The new classification system enables the understanding of relationships between water-gap complexes of taxonomically unrelated species with PY.

Plastid genomes of flowering plants are largely identical in gene order and content, but a few lineages have been identified with many gene and intron losses, genomic rearrangements, and accelerated rates of nucleotide substitutions. These aberrant lineages present an opportunity to understand the modes of selection acting on these genomes as well as their long-term stability. My research has focused on two areas within plastid genome evolution in Geraniaceae: first, an investigation of the diversity of unusual plastid genomes in a single genus, Erodium (Geraniaceae) for chapters one and three. Chapter two focuses on the evolution of subunits of the plastid-encoded RNA polymerase (PEP). The first chapter described the loss of plastid-encoded NADPH dehydrogenase (ndh) genes from a clade of 13 Erodium species. Divergence time estimates indicate this clade is less than 5 million years old. This recent loss of ndh genes in Erodium presents an opportunity to investigate changes in photosynthetic function through comparative biochemistry between Erodium species with and without plastid-encoded ndh genes. Second, I examined the evolution of the gene encoding the alpha subunit (rpoA) of PEP in three disparate angiosperm lineages—Pelargonium (Geraniaceae), Passiflora (Passifloraceae), and Annonaceae—in which this gene has diverged so greatly that it is barely recognizable. PEP is conserved in the plastid genomes of all photosynthetic angiosperms. I found multiple lines of evidence indicating that the genes remain functional despite retaining only ~30% sequence identity with rpoA genes from outgroups. The genomes containing these divergent rpoA genes have undergone significant rearrangement due to illegitimate recombination and gene conversion, and I hypothesized that these phenomena have also driven the divergence of rpoA. Third, I conducted a survey of plastid genome evolution in Erodium with the completion of 15 additional whole genomes. Except for Erodium and some legumes, all angiosperm plastid genomes share a quadripartite structure with large and small single copy regions (LSC, SSC) and two inverted repeats (IR). I discovered a species of Erodium that has re-formed a large inverted repeat. Demonstrating a precedent for loss and regain of the IR also impacts models of evolution for other highly rearranged plastid genomes. / text

Pelargonium sidoides DC. (Geraniaceae) root extracts are used in the Eastern Cape Province of South Africa as a traditional medicine for the treatment of respiratory tract and gastro-intestinal infections. Ethanolic extracts are used globally as herbal treatments for bronchitis, asthma and as an immune system booster. Despite documented exploitation of wild populations by illegal harvesters, this species has not been awarded a protected status. The high level of harvest in the years preceding this study prompted this investigation of the prospects for sustainable root harvest through wild harvest and greenhouse cultivation. A novel method was developed for the purification of umckalin, a bioactive constituent in root extracts, such that the root umckalin concentrations of wild and cultivated plants could be quantified by HPLC. As part of the cultivation experiments, the concentration of umckalin in roots was measured for plants across part of the species’ distribution range in the Eastern Cape Province. This survey revealed that root umckalin concentrations were inversely related to the average annual rainfall of the collection site (r² = 0.94, p = 0.007) and directly related to soil pH (r² = 0.97, p = 0.002). Thus, the possibility of inducing high umckalin concentrations in greenhouse-cultivated plants was investigated by subjecting plants to rapid and prolonged water stress treatments. Two leaf applied hormone treatments (cytokinin and gibberellin) and a root competition treatment with a fast growing annual (Conyza albida) were also investigated based on the potential function of umckalin in P. sidoides plants. These five treatments did not significantly affect root umckalin concentrations compared to well-watered controls. The results of further experiments suggested that umckalin production may have been influenced by the geographical origin and genetics of plants rather than environmental variation. Following wild harvest experiments, the regrowth of replanted shoots from which a standard proportion of the root was harvested showed that water availability affected shoot survival but not root regrowth rate. Regrowth rates were low, questioning the viability of wild harvest. In contrast, greenhouse cultivated plants showed ca. six times greater growth rates, supporting the cultivation of roots to supply future market demand.