Fruit displays of indigenous and invasive alien plants in the south-western Cape

Abstract

Two models are introduced which describe different strategies for presenting fleshy fruits of indigenous and alien plant species. Each model describes a gradient between two end-points. In the first model one endpoint is occupied by plant species with large, conspicuous, synchronized, short duration fruit displays. The other end-point of this gradient is occupied by species with less conspicuous fruit displays, but presented over a longer fruit season. In the second model, one end-point is occupied by species which maximize all aspects of fruit displays, though presented without regard for seasons. The contrasting end-point of this gradient is occupied by species which minimize their investments in regularly presented fruit displays. It was hypothesized that alien species would possess an intensive, and or a maximized fruit display, whereas indigenous plants would possess all types of fruit displays. The fruit displays of eight indigenous and six alien woody species are characterized relative to these models. The data was consistent with that of the hypothesis, with alien species favouring a seasonally short but intense fruit presentation, whereas many indigenous species have prolonged fruit presentations. Minimized fruit displays were only recorded for indigenous species, whereas maximized fruit displays were recorded for indigenous and alien species.