Mt Elgon is one of the oldest and greatest volcanic mountains in East Africa, which is located at the boundary of Kenya and Uganda about 120 km North of Lake Victoria. It hosts a unique ecosystem that forms part of the African Afromontane center of endemism. However, the number of species reported in this ecosystem has been changing over time. The absence of a comprehensive up-to-date checklist hampers priority species conservation and implementation of biodiversity management policies in Mt Elgon.

Researchers documented a comprehensive list of the vascular plants of Mt Elgon from random-walk survey and retrieval of herbarium specimen dating back to 1900.

The study reveals that the flora of Mt Elgon constitutes 1709 taxa (1589 species, 75 subspecies and 45 varieties) representing 673 genera in 131 families. The plant taxa are classified into five classes, namely: Magnoliopsida 1230 species (72%), Liliopsida 396 species (23%), Polypodiopsida 72 (4%), Lycopodiopsida 7 species (0.4%), and Pinopsida 4 species (0.2%). The plant life forms of Mt Elgon are categorized as either trees, shrubs, climbers, lianas, or herbs. During field excursions between the year 2018 and 2019, one new species (Peponium elgonense) of the family Cucurbitaceae is discovered.

This checklist records respective habitat, habits, elevation ranges, voucher numbers and global distribution ranges of each species. Native and exotic species are also distinguished, where 8.4% of the total species in 49 families are exotic species. There are 103 endemic species, while 14 species are found to be both rare and endemic. IUCN conservation status reveals two Critically Endangered, four Endangered, nine Vulnerable and two Near Threatened species. They also make herbarium collections and take photographs of plants endemic to Mt Elgon, as well as rare and endemic, regional endemic, and exotic species.

This study presents the first and most comprehensive plant inventory of Mt Elgon that will facilitate further ecological and phylogenetic studies.

Though there are evident efforts of forest regeneration through massive plantation and forest intrusion mitigation policies, it is pertinent that both governments of Kenya and Uganda join efforts to enforce planting native and indigenous trees, shrubs and herbs. This will in turn elude the impending forest structure transformation and improve the capacity of Mt Elgon to sustain its ecosystem (flora and fauna), which forms the basis of livelihood to the surrounding population.

The research has been published in the journal of Phytokeys. Peninah Cheptoo Rono, guided by Professor WANG Qingfeng and Professor HU Guangwan from Wuhan Botanical Garden, is the first author. It was funded by the International Partnership Program of Chinese Academy of Sciences (CAS), the Natural Science Foundation of China and Sino-Africa Joint Research Center, CAS.

Wuhan Botanical Garden in collaboration with the National Museums of Kenya, Sino-Africa joint research group and other government units responsible for biodiversity, have completed floristic survey on biodiversity rich regions of Kenya including Mt Kenya, Mt Elgon, Aberdare ranges, Cherangani Hills, Nandi forest, and the Coastal forests. This data is significant for the compilation of the Flora of Kenya. (Published: 4 April 2023)

 Floristic divisions of Kenya and Uganda and location of Mt Elgon (Image by WBG)

Different growth forms of the vascular plants of Mt Elgon (Image by WBG)

Photographs of specimens collected from Mt Elgon A(i,ii,iii) Peponium elgonense (new species), B Swertia crassiuscula (regional endemic), C Plantago lanceolata (exotic), D Indigofera homblei (exotic), E Tripogon major (rare and endemic), F Aloe elgonica (Endemic to Mt Elgon) (Image by WBG)