The classification of cacti has been an ever-changing task that has consisted of a
good deal of naming and renaming. This struggle to agree on classification continues
today and is the topic of much debate among cactus enthusiasts. This is due in large part
to the extremely variable growth habits of most cacti. Many cacti plants of the same
species may appear quite different from one another. Cacti also reproduce proficiently
through vegetative means creating large numbers of a particular variation and therefore
furthering the impression that what is actually a variety is instead a unique species. The
fact that there exists no agreed upon definition of what a "species" actually is contributes
even further to the problem.
Because of this, publications written by both amateurs and professionals that describe and
classify cacti create a lot of confusion as to which names and groups are to be accepted and
which are not. Most classification was performed by individuals up until 1984 when the
International Cactaceae Systematics Group was formed to standardize the classification of cacti.
This may seem like the perfect solution to the problem, save that the International Cactaceae
Systematics Group (ICSG) is also made up of individuals. Again, without a standard definition as to
differentiating between species, much of their work is based on strong beliefs and opinions -educated as
they may be. This creates confusion for those attempting to identify an individual cactus plant.
With that said, CactiGuide.com has a tremendous advantage due to being web-based. By utilizing the dynamic nature of
a website, one can find a species listed under whatever name one prefers and that way serves the ultimate purpose of any
classification system. Furthermore, with the development of the CactiGuide.com Custom Nomenclature application, the
taxonomic "opinions" of multiple individuals and publications are now available for contrast and comparison.
CactiGuide.com claims no one system of classification as correct over the other. The listing of taxa reflect the combination
of multiple systems and therefore includes more taxa than any other system. In a sense, it is the ultimate "splitters"
reference. This is not done to say that all those names are valid, but so that each name can be addressed as a reflection
of taxonomic history, even if only to say that the names are no longer accepted by anyone. To demonstrate this, a
chart is provided for each taxon that lists the various treatments by publications of that taxon. This chart can
be accessed via a link on the detail page for each species.
For a more detailed explanation of the CactiGuide.com Custom Nomenclature application and to view the various treatments,
visit this page.
I have not listed the name of the person(s) who first described the plant along with the synonyms as is the custom to do because it is not
necessary for identification. However, there is a link under the synonym list for each species that lists all the Author and Publication data
according to IPNI and a link for each name to the IPNI database.
NOTE: CactiGuide.com is intended as a source for the positive identification of a particular cactus plant as its Primary Objective.
Since its inception, it has developed to be a more complete treatment of many aspects of the Cactus Family including biological information,
histories, conservation, and horticultural information. And while becoming more and more comprehensive, it should never be treated as
an exclusive reference. I strongly recommend referencing other material on the subject such as those listed on the sources
page which collectively provide an inexhaustible wealth of additional information.