Helleborus with its various different species belongs to the buttercup (Ranunculaceae) family, along with other popular genera, such as clematis (Clematis), delphinium (Delphinium) and globeflower (Trollius).
There are two main groups of Helleborus. They are the caulescent and the acaulescent groups. The acaulescent species produces no stems while the caulescent species do produce stems. The rootstocks of these two groups are also different. The caulescent species cannot be produced from division.
The following list of Helleborus species, compiled by Joseph Woodward in 2006, contains information on which of the two main groups each species belongs to.
For more detailed information about any of the species listed, please click on the species name.
On this list H. abruzzicus and H. liguricus are described as species of their own. Furthermore H. bocconei, H. istriacus and H. hercegovinus are listed as independent species, which were observed as subspecies of H. multifidus in the past.
The Christmas Rose (H. niger) belongs to a group of its own. It produces no stems and might belong to the acaulescent species but H. niger differs from the other species of the Helleborastrum group, including all the acaulescent species except for H. thibetanus.
Hellebores are subdivided by Brian Mathew into six groups. The classification of the different groups is based on the following parameters:
- The presence of stems
- Carpels grown together at the base or not
- shape and texture of the anthers
- Size and shape of the seeds
- Ability of the plants to hybridize
- Differences of the leaves
- Colour of the flowers
This leads to following classification: