Reshnee Lalla South African National Biodiversity Institutes’ Invasive Species Programme (ISP)* with inputs from Lorraine Strathie Agricultural Research Council-Plant Protection Research Institute (ARC-PRRI) P arthenium hysterophorus (locally called Famine Weed, Parthenium, Demoina Weed and Umbulalazwe), is an annual herbaceous plant. Famine Weed has invaded the northern and eastern regions of South Africa and many countries along the eastern seaboard of Africa and is also a widespread invader in Asia and Australia. It spreads at a rapid rate due to several factors including climatic suitability, prolific seed production, and the unintentional facilitation of seed spread via vehicles, machinery, water, animals and various other human-related activities. Parthenium hysterophorus causes a range of impacts, from human and animal health effects to biodiversity loss, and massively reduces animal and crop agricultural production. It causes severe economic losses in many areas where it has invaded around the world, impacting in particular on the livelihoods of subsistence farmers and rural communities. Health complications may arise from the allergic reactions displayed by many people who have frequent exposure to the plant. South Africa has realized the severity of Famine Weed and in 2014 produced the National Strategy for the Management of Famine Weed, and an associated National Implementation Plan to facilitate coordinated management of this species at national, regional and local levels (accessible at www.issa.org.za). Chemical control is being used to reduce the spread, by targeting outlier populations. However, the main effort is going into biological control to reduce the species’ invasive potential in the long term. As budget is limited and the control teams dealing with Famine Weed in outlying areas often need to travel long distances to spray these outliers, the correct identification of the plant is critical. Due to occasional confusion with plants of the closely related Ambrosia genus also present in South Africa, a basic Identification guide to distinguish Famine Weed from Ambrosia species (especially when plants are very young and not yet flowering) was developed.