Green hellebore (Helleborus viridis) is in the buttercup (Ranunculaceae) family. The big green 'petals' are actually not true petals but sepals.
Helleborus viridis is a native of shady woodland glades on lime-rich soils, although provenance can be tricksie as it was (and still is) widely planted in gardens, from whence it escapes. These plants were, however, in a typical assemblage of woodland species. The New Atlas of the Kent Flora (Eric Philp, 2010) does record it being north of Folkestone, so I suspect it may be native here.
Hellebores are toxic, especially the roots. Ancient herbals (Dioscorides, Hippocrates) list hellebore as an ingredient in abortifacients (an article from UCL is here). Pliny (referring to black hellebore, Helleborus niger) describes an ancient custom of praying to the gods before digging up the plant and also checking that no eagles were in the immediate vicinity. If the eagles saw you, you'd die within the year (or quicker one supposes if you ate the root you'd just dug up).
Wikipedia refers to several legends concerning hellebores (of various species). The daughters of the King of Argos were (allegedly) given hellebore to cure a madness which made them run through the city naked and weeping. One assumes the violent emetic properties of the root were believed to purge the body of other toxins. Another Greek legend says that hellebore was used in early botanical warfare to poison the water of a besieged city. Diarrhoea weakened the defenders so much they couldn't defend the city.
The origin of the name hellebore is a little obscure but it possibly means 'food for a fawn'. Garden centres sell hellebores as 'deer proof' ground cover, so Bambi wouldn't do so well munching it. Unlike humans deer have more sense and avoid it. Green hellebore is also known as bear's foot (why?), green lily or fellon's foot.
Mrs Grieve, confusingly, calls Veratrum viride, green hellebore. Veratrum viride is actually the name of the green false hellebore, a native of north America. Green false hellebore is also toxic. Mrs Grieve says that a 'moderate dose' slows the pulse and slows breathing. Hmmm.
This picture of Veratrum viride is from Wikipedia
According to Wikipedia 'The plant was used by some [North American] tribes to elect a new leader. All the candidates would eat the root, and the last to start vomiting would become the new leader'. Sounds way more interesting than a General Election.
Veratrum viride is also called Indian Poke and thus not to be confused with the other Indian Poke Phytolacca spp (which looks nothing like a hellebore). Common plant names are so befuddling :-/
Before we leave Veratrum it is interesting to note that the genus (actually the alkaloid cyclopamine from Veratrum californicum) was key to uncovering the sonic hedgehog protein in the hedgehog signalling pathway in mammalian embryology. The sonic hedgehog not Sonic 'the' hedgehog. The hedgehog signalling pathway provides cells with cues that ensure an embryo develops correctly. Reference here (and another fascinating paper behind a paywall here - grumble, grumble).
When we visited Walmer Castle a few days later there were heaps of hellebores in flower.
They tried to brighten up a dull old day. Is this white one Lenten Rose?
Some were jolly pretty.
I've really no idea what these cultivated species are but I don't think they compare with the subtle beauty of our native green woodland rose.