Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Physiological mechanisms for the rapid growth of Pennisetum clandestinum in Mediterranean climates.

Abstract

Kikuyugrass, Pennisetum clandestinum, is a C4 grass that has become an invasive weed in temperate climates. The ecophysiological mechanisms that have allowed it to become a successful weed in these locations were examined by comparing P. clandestinum and 2 other common turfgrass species, Festuca arundinacea (tall fescue cv. Mojave, a C3 cool-season grass), and Stenotaphrum secundatum (St. Augustinegrass, a C4 warm-season grass), grown in a warm or cool growth regime. Rates of photosynthesis were measured over a range of leaf temperatures as were the growth rate parameters of these species. At leaf temperatures between 25 and 40°C, P. clandestinum maintained the highest rates of photosynthesis in both temperature regimes. Under warm temperatures, this species rapidly increased biomass and leaf area to a greater extent than either of the other 2 grasses. Theoretical whole plant photosynthesis (mean leaf area × mean photosynthetic rate) was higher for P. clandestinum than for the other 2 species in both growth regimes and over most leaf temperatures. The results suggested that P. clandestinum is a successful weed in Mediterranean climates as a result of its capacity to photosynthesize over the full range of temperatures found in those climates, its rapid growth during warm weather, and its apparent tolerance to moderately cool temperatures.