Rasaminirina, F. | bioRxiv Science

bioRxiv2024

Advancing knowledge of West African morning glories: a taxonomic revision of Ipomoea L. (Convolvulaceae) from Ghana

Ghanas plant diversity is estimated at 2,974 plant species, belonging to 1,077 genera and 173 plant families. However, a Flora of Ghana is yet inexistent: targeted floristic and taxonomic studies are still much needed to document the plant diversity of the country fully at the family, generic and species levels. This is essential for identifying priority conservation areas in the country and support further research in crop wild relatives or medicinal plants, which will help tackle food insecurity and improve livelihoods. In this study, we provide a taxonomic revision of the Ipomoea spp. in Ghana to enhance their identification, conservation and sustainable utilization as food and medicine among other uses. An extensive literature review was carried out, including historical references and online taxonomic databases, to recover information on accepted names, type specimens and synonyms, followed by consultation of herbarium specimens at GC herbaria, to retrieve morphological information and database specimens. Specimen locality information was georeferenced, and records plotted onto distribution maps. As a result, this work provides an identification key to the species of Ipomoea of Ghana, nomenclatural information, comprehensive morphological descriptions, detailed list of examined specimens, distribution maps and notes on conservation status and traditional plant uses. In total, 28 species are fully described, 20 of which are native and eight introduced from the Americas; five are new records to Ghana.

plant biology↗

bioRxiv2023

The grass that built the Central Highland of Madagascar: environmental niches and morphological diversity of Loudetia simplex

1) Research Aims -- Loudetia simplex is a common and dominant species throughout grassland ecosystems in mainland Africa and Madagascar. It is highly polymorphic, often classified as two taxa endemic to Madagascar: L. simplex subsp. stipoides and L. madagascariensis. A better understanding of the inter- and intra-specific variation between these taxa and its contributing environmental factors could improve our understanding of the history of Madagascars grasslands. 2) Methods -- The taxonomic status of L. simplex subsp. stipoides and L. madagascariensis was evaluated by morphometric analyses of 119 herbarium specimens. Species distribution modelling was used to determine the most important environmental factors underlying the L. simplex distribution in Madagascar versus other African grasslands. We investigated if L. simplex in Madagascar could be predicted by distributions across mainland Africa with niche overlap analyses. 3) Key Result -- African and Malagasy species exhibited variation potentially associated with environment. Specimens from northern and western Madagascar were taller with smaller spikelets than those from Southern Africa and central Madagascar. Loudetia simplex typically occurred in cooler temperatures with high precipitation and pronounced seasonality, but taller populations were found in warmer conditions. Projecting ecological niches of Southern Africa and East Tropical Africa onto Madagascar demonstrates much of the present distribution in the Central Highlands is expected from other natural African grasslands. 4) Key Point -- Malagasy and African individuals represent a single species, and the Malagasy species can be considered as a synonym of L. simplex. Distribution models are congruent with pre-human presence of grasslands in Madagascar. SOCIETAL IMPACT STATEMENTUnderstanding dominant species like Loudetia simplex is necessary to understand the fire-driven grassy ecosystems they create. In Madagascar, grasslands are considered a low-value ecosystem despite their unique biodiversity and crucial importance as zebu rangeland. Only 1.8% of Madagascars grasslands are protected despite facing similar threats to forests and biodiversity loss. This study of common grasses will support the management of protected areas by providing information on resource management of vulnerable open ecosystems in Madagascar. Distribution models of common grass species and clear taxonomic classification can help land management stakeholders identify natural grasslands versus degraded forests.

ecology↗