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Background and Aims It is unclear how widespread polyploidy is throughout the largest holocentric plant lineage—the Cyperaceae. Because of the prevalence of chromosomal fusions and fissions which affect chromosome number but not genome size, it can be impossible to distinguish if individual plants are polyploids in holocentric lineages based on chromosome count data alone. Furthermore, it is unclear how differences in genome size and ploidy levels relate to environmental correlates within holocentric lineages, such as the Cyperaceae. Methods We focus our analyzes on tribe Schoeneae, and more specifically, the southern African clade of Schoenus. We examine broad-scale patterns of genome size evolution in tribe Schoeneae and focus more intensely on determining the prevalence of polyploidy across the southern African Schoenus by inferring ploidy level with the program ChromEvol, as well as interpreting chromosome number and genome size data. We further investigate whether there are relations between genome size / ploidy level and environmental variables across the nutrient-poor and summer-arid Cape biodiversity hotspot. Key Results Our results show a large increase in genome size, but not chromosome number, within Schoenus compared to other species in tribe Schoeneae. Across Schoenus, there is a positive relation between chromosome number and genome size, and our results suggest that polyploidy is a relatively common process throughout the southern African Schoenus. At the regional scale of the Cape, we show that polyploids are more often associated with drier locations that have more variation in precipitation between dry and wet months, but these results are sensitive to the classification of ploidy level. Conclusions Polyploidy is relatively common in the southern African Schoenus, where a positive relation is observed between chromosome number and genome size. Thus, there can be a high incidence of polyploidy in holocentric plants, whose cell division properties differ from monocentrics.

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Relationships between environmental factors and the distribution patterns of sedges were studied in the wetland important bird areas of Uganda. Vegetation data were collected using the transect and quadrat methods. Four quadrats were located at each sampling point at 10 m intervals along the transect from dry land to open water. Relative abundances of sedges were recorded in each quadrat. Inventory sampling was done to record species that were not recorded on the transects so as to generate near complete species lists. Human influences on vegetation such as harvesting, fire and vegetation modification were examined along the transects. Soil samples were collected along the transects for analysis of P, K, Na, Ca, Mg and organic matter. Other parameters recorded from water samples included water levels, pH and water conductivity. Rainfall and altitude were also recorded. Canonical correspondence analysis was used to correlate the relative abundances of the species to measured environmental variables. Linear correlation of the environmental variables with principal components indicated that water levels, altitude and rainfall were major factors that influenced the abundance and occurrence of sedges in the different bird areas. Sedge distribution patterns are a function of local geological and edaphic factors; and human‐induced exogenous disturbances.

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