Senecio extensus (subalpine fireweed) is a perennial herb that was only known in Tasmania from a single collection made in 1984 until confirmed in 2020 from two sites on a broad undulating area of dolerite-based sedgy plain surrounded by open shrubby subalpine forest at about 1,000 m a.s.l. The two Tasmanian sites are in one sub-population, the total area of occupancy less than 1 ha and the total number of mature individuals fewer than 250. Limited direct threats are identified but the apparently highly localised occurrences place the species at risk of stochastic events. Appropriate management of the known sites, and extension surveys to detect novel occurrences and better understand threats and management needs are considered the key management objectives.