Habitat management news
New zealand Pigmyweed Cassula helmsii is well recognised as an invasive aquatic plant, introduced through the domestic aquaria and horticulture trade. Growing throughout the year, it blocks drainage ditches, and smothers and outcompetes native aquatic species. It is very difficult and costly to eradicate once present. Herbicides fail to penetrate the thick mats, and fragments easily break away and grow to form new colonies.