Helleborus belongs with its different species to the buttercup family (Ranunculaceae), such as Clematis, Delphinium and 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 on the right side comes from Joseph Woodard (2006) and shows where the different species belong in these two groups.

To get more information about the individual species please click at the right side at the name of species.

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:

1. Syncarpus: H. vesicarius
2. Griphopus: H. foetidus
3. Chenopus: H. argutifolius, H. lividus
4. Helleborus: H. niger
5. Helleborastrum: H. abruzzicus, H. atrorubens, H. bocconei, H. croaticus, H. cyclophyllos, H. dumentorum, H. hercegovinus, H. istriacus, H. liguricus, H. multifidus, H. occidentalis, H. odorus, H. orientalis, H. purpurascens, H. torquatus und H. viridis.
6. Dicarpon: H. thibetanus

Today we have hybrids that have risen from either natural or handmade crossings between different helleborus species.
The hybrids between acaulescent species sometimes lead to misunderstandings, because they are unfortunately described wrongly as H. orientalis. The correct description of these hybrids should be: H. x hybridus.

The caulescent hybrids are:
- H. x sternii: Hybrid of H. lividus and H. argutifolius
- H. x ericsmithii: Hybrid of H. x sternii and H. niger
- H. x nigercors: Hybrid of H. argutifolius and H. niger
- H. x ballardiae: Hybrid of H. lividus and H. niger
- H. x glandorfii: Hybrid of H. niger and H. atrorubens

To get more information about the caulescent hybrids please click on the name of species at the right side.