Er.We@Flickr notes that the species / hybrids in the photograph are: Helleborus orientalis, Helleborus foetidus, Helleborus argutifolius, and Helleborus ×ericsmithii. The top row, displaying the back of the flowers, is paired with the bottom row showing the face (with the exception of the last two pairs on the right).
The common names for a few of these species / hybrids are related to the time of year these bloom (in the northern hemisphere): Lenten roses or Lenten hellebores. Helleborus foetidus is more commonly known as stinking hellebore while Helleborus argutifolius is referred to as Corsican hellebore. Wikipedia has an extensive article on hellebores, including sections on uses in horticulture and history. Hellebores.org has detailed descriptions of the species as well as a strong selection of photographs.
I should note that many of the hellebores in UBC Botanical Garden are in a similar state of flowering at the moment.