Systematics, Ethnobotany and Conservation of the Genus Kalanchoe Adans. (Crassulaceae) in Kenya
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Date
2025-12
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Kenyatta University
Abstract
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
Description
A Thesis Submitted in Fulfillment of the Requirements for the Award of the Degree of Doctor of Philosophy (Plant Taxonomy) in the School of Pure and Applied Sciences of Kenyatta University. December, 2025
Supervisors
Emily Wabuyele
Grace Gatheri
Olwen Grace,
Charlotte Bjorå,