Wuhan Botanical Garden, cooperated with National Museums of Kenya, found a new species  of Premna (Lamiaceae) from the coastal forests of Kenya, Cha Simba area in Kilifi County. Lamiaceae is the largest family of the order Lamiales, comprising more than 200 genera and 7,000 species in the world. They mainly distribute in Old World tropical and subtropical regions from Africa, Asia, Australia, and various islands in the Pacific and Indian Oceans. In East Africa, there are about 17 species with 10 species distributed in Kenyan floral regions. 

Members of Premna are usually shrubs, trees or woody climbers; with leaves simple, opposite or in whorls of 3-4; cymes often terminal; flower small; calyx not obviously caccrescent in fruit; corolla tube short, lobes 4, spreading; stamens 4, usually didynamous; ovary 4-locular, ovules 1 per locule; fruit a small drupe, with fleshy mesocarp and a 4-locular pyrene.  

Supported by Sino-Africa Joint Research Center, in the course of fieldwork investigations in 2020 under the organization of National Museums of Kenya, Dr. Veronicah Mutele Ngumbau, graduated from Wuhan Botanical Garden, collected an unusual Premna L. species from the coastal forests of Kenya, a woody climber, which looked different from other members of the genus found in the East Africa.  

After checking and comparing the collected plant with all known species found at the East Africa Herbarium, they found a similar specimen of the unusual Premna species collected from the same locality by a young botanist named Mwadime Nyange of the Museum in 2019. However, it was unnamed at that time. Dr. Ngumbau and his doctoral supervisor, Professor HU Guangwan conducted further comparative studies, and after consulting Postdoc LI Bo, a taxonomic expert on plants, they confirmed this unusual plant was a new species. It is similar to that of P. chrysoclada Gürke and P. tanganyikensis Moldenke, however, it differs significantly from the two species. 

The life form of this species is scandent shrub or liana, older stems with persisting thorns, not ridged and not corky, branchlets, petioles, and inflorescences densely golden-brown dendritic pubescent, inflorescence short cyme on lateral and terminal shoots, and calyx tubular, ca. 3 mm long, lobes broadly triangular, ca. 1 mm long, densely dark brown dendritic-pubescence. Those features suggest that the new species is distinctly different from related species of this genus and their species. It is thus identified as a distinctive and undescribed new species. 

Thanks to Dr. Ngumbau’s discovery and his contribution to the investigation and research of Flora of Kenya, the new species is named after him: Premna mwadimei V.M. Ngumbau & G.W. Hu.  

The result has been published on Phytotaxa, a International Journal of Plant Taxonomy, under the title “Premna mwadimei (Lamiaceae), a new species from Cha Simba, a remnant of coastal forests of Kenya, East Africa”. This work was supported by grants from the International Partnership Program of Chinese Academy of Sciences, National Natural Science Foundation of China and Sino-Africa Joint Research Center, CAS. 

Premna mwadimei sp. nov. A. Habitat. B. Abaxial side of leaf blade. C. Adaxial side of leaf blade. D. Branch with fruits and flowers. E. Branch showing abaxial side of leaf and leaf arrangement. F. Inflorescence. G. Thorny stem. H. Ripe fruits. Scale bar: B & C = 2 cm, H = 7 mm. (Photographs by V .M. Ngumbau & Mwadime)