It’s surely the most unattractive name for any rare British flower. It is, however, about as unforgettable as the organism itself: stinking hellebore is a beast of a plant. This big perennial has fleshy, lime-coloured upper parts that can grow as high as 80cm. Yet, oddly, the basal leaves are so unalike that it’s as if they arise from a different species. The latter are narrow, darkest emerald and serrated along their blade-like edges, but most noteworthy is that they are actinomorphic – symmetrical in more than a single plane. These pioneer plants, before they acquire the flowering shoots, create the most intricate yet equal-halved spheres. I’d name it the most attractive aspect, were it not for the singularity of the flowers, which are in bloom right now. Indeed, some southern European relatives are at their best by November. The flowers grow in globular bunches like unripe waxy tomatoes or, better still, like vegetative testicles, with their heads faced directly downwards. Along the lowest edge of this luminous lime ball is a pencil-line of exquisite burgundy. A tangential reflection as we took in the splendour of the colony is why so many scarce plants grow in apparent profusion – and there were scores of them here – but only at the one spot. I’ve never knowingly found stinking hellebores wild, with most of my records referring to escaped cultivars. Gardeners value hellebore for its beauty, but also because it was once a plant with purpose. Like many in the ranunculus family, it is poisonous: hellebore derives from the Greek words elein (to injure) and bora (food). It was used as a cure for boils or spots, but also intestinal worms in children, with the singular disadvantage that it regularly wiped out the patient as well as their parasites. Of all rare plants, this particular one had a deep sense of the dramatic in its location. Scarthin Rock is a great limestone outcrop that was part-blasted away to facilitate road construction through the Derwent Valley. On one side, the flowers gaze down on Cromford Mill, a Unesco world heritage site, and, on the other, at Willersley Castle, home of the cotton mill mogul Richard Arkwright.