PHD-Department of Plant and Microbial Sciences

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Browsing PHD-Department of Plant and Microbial Sciences by Author "Evusa, Gertrude Vwononi"

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    Systematics, Ethnobotany and Conservation of the Genus Kalanchoe Adans. (Crassulaceae) in Kenya
    (Kenyatta University, 2025-12) Evusa, Gertrude Vwononi
    Kalanchoe Adans. (Crassulaceae) comprises about 175 succulent species, native to tropical Africa and Madagascar with 19 occurring in Kenya. Most (68.4%) remain unassessed for conservation status and their taxonomy and phylogeny are unclear due to morphological variation, hybridisation, polyploidy and overlapping distribution. Although used as ornamentals and medicinal plants in many parts of Africa, the uses of Kalanchoe species in East Africa have not been systematically documented. The objectives of this study were to clarify species boundaries within the K. lateritia and K. nyikae complexes, determine their phylogenetic relationships using molecular and morphometric analyses, document the traditional uses and assess conservation status. Morphological data obtained from herbarium specimens was analysed using PAST programs while molecular studies utilized DNA extraction from leaf samples using EZNA kits, sequencing of the data through the Angiosperm 353 probe kit, and analysing it under the maximum likelihood criterion. Ethnobotanical data was collected using interviews and semi structured questionnaires in six flora regions. Conservation status was evaluated based on field observations of threats, Area of Occupancy (AOO), and Extent of Occurrence (EOO) through Geospatial Conservation Assessment Tool (GeoCAT). Taxonomic findings indicated K. nyikae as monophyletic supporting its subspecies, K. nyikae subsp. auriculata as valid rather than a hybrid. Conversely, K. lateritia varieties revision was highlighted, combination of K. lateritia var. lateritia and K. lateritia var. prostrata into one variety/subspecies and retention of K. lateritia var. pseudolateritia as a separate variety/subspecies. Phylogenetic analyses resolved two main clades, confirming Kalanchoe as broadly monophyletic, and K. subg. Kitchingia and K. subg. Bryophyllum polyphyletic. Kalanchoe exhibited uncertain relationships among six subclades. The study revealed that Kalanchoe species in Kenya are mainly used as ornamentals and in traditional medicine for treating injuries, wounds, gastrointestinal problems and infections in humans and poultry. Kalanchoe prittwitzii, K. densiflora and K. lateritia were most cited. Conservation assessments categorised three species as critically endangered (CR), 12 as Endangered (EN) and four as Vulnerable (VU), under IUCN (2022) criteria. A comprehensive evaluation upgraded K. lateritia and K. nyikae sensu stricto to EN from LC due to their low AOO resulting from severely fragmented or few localities and ongoing decline–criterion 2ab (iii) and significant habitat threats. The threats include habitat loss, anthropogenic activities and prolonged drought and floods. Findings from this study emphasize the need for clear species delimitation to support identification, management, and sustainable utilisation. Conservation efforts should focus on raising awareness, sustainable use, and inclusion in in-situ and ex-situ conservation initiatives. Taxonomic revision, further research using other molecular tools and broader sampling to refine phylogenetic and taxonomic relationships, phytochemical studies of the medicinal species and IUCN red list update are recommended