Limpwurt roots are received from looting the chest in the south-east corner of New Varrock, which is accessible after completing Dimension of Disaster: Demon Slayer. The apothecary can create a strength potion with these, together with red spiders' eggs at the cost of 2 zemomarks. This chest can only be looted once, and no more limpwurt roots can be obtained in New Varrock afterwards.