Phenotypic variation within contrasting environments: a study of the invasive macrophyte, Hymenachne amplexicaulis across Australia

摘要

Hymenachne amplexicaulis (Rudge) Nees is an aggressive invader of northern Australia's wetlands and waterways. The species is widespread, occurring extensively through the Northern Territory, Queensland and northern New South Wales. Currently there islimited information regarding the abiotic and biotic factors influencing the phenology of the plant. Such knowledge is essential to understand the invasion potential of the species, and to design effective management strategies. With this in mind the current study was undertaken to examine phenological variation (including growth, flowering and seeding events, and germination) within//, amplexicaulis populations across a range of environments. In addition the phenology and growth conditions of//, acutigluma (Steudel) Gilliland (native hymenachne) and H. amplexicaulis were compared where both plants were growing side by side. Initial results indicate variation in flowering and seeding events within and between environments. Where both species grow together, H. amplexicaulis flowers and seeds later in comparison to H. acutigluma and is restricted to shallower water depths. That a percentage of both populations flower simultaneously suggests that hybridisation of the two species is possible. Managementimplications are discussed.