Cactus & Succulent Society
of New Zealand (CSSNZ)

Nomenclature of Cactus or any plant

Why name C&S or anything?

"Describe me the thing precisely as you will, I can make no use of it without a name .... names are the alphabet of natural knowledge"                                                 Linnaeus

When talking about something, people need to agree on what they are discussing, whether it be a plant, an animal or an inanimate object like a "chair". That's one reason we name things.

How do you identify people?

I'm off to lunch with the "The young lady who lives in Main St. who works at the deli!"
So it was with plants before a guy called Carl Linnaeus came along with his botanical naming system … so before Linnaeus your plant was called "the large cactus that grows in Arizona" or some similar long worded descriptive name.

But what if there are two young ladies who live in Main St., who work at the deli?
Just as there ARE more than two large growing cactus in Arizona. Sure we could further describe it as the "large cactus that grows in Arizona that branches from the base like an organ pipe" but taking this concept further eventually results in large unwieldy names for plants.

So now, how about identifying the person above as "Lucy Jones" … doesn't that define that person uniquely (assuming there is only one "Lucy Jones").
In the same way you called the plant above "Stenocereus thurberi" and everybody (who knows cactus) would know exactly what plant you were talking about, and unlike people there can't be two identical botanical names for different plant species.

The Linnaeus binominal botanical naming system

Early naturalists noticed that certain plants or animals may be related to others that looked similar or had similar characteristics.


Carolus Linnaeus was professor of natural history at the University of Uppsala in Sweden when in the mid 1700s he devised the system we still use to this day to classify all living things.
Linnaeus called all the same organisms a species, similar species were grouped into a genus, and similar genera into a family, and then similar families were placed in an order, similar orders in a class and similar classes in a phylum. Lastly phyla are placed into either the plant or animal kingdom.
When naming an organism we use the species and genus name, which is called binomial nomenclature and when the plant is named everyone knows what exact species is being talked about.

The first part of a plant name is the genus (plural: genera) and is like us (European) human's surname or family name .
Each species (species is singular and plural) name is like us (European) human's "first name" although it is written second.

The names are of Greek or Latin origin, were to be mainly descriptive (later they could also reflect a person involved in the plant's discovery, or the area of habitat, or anything the author/discover wishes), naming is to follow strict rules of validity e.g. publication in Latin in a reputable journal, depositing of a specimen in a herbatorium, the name itself to follow rules etc. . If the plant is in a new genus, the author may choose the new generic name, the new species name is given by author. The species name must not have been used before for a plant in that genus.

When the first cacti came to Europe from the 'New World' as it was "discovered" by the European explorers, Linnaeus knew they were members of a new genus not seen in the 'Old World' before, and he coined the genus Cactus, derived from Kaktos, the Greek term for thistle.

Linnaeus named 22 species of cactus in the single genus "Cactus" in 1753's "Species Plantarum" book.

As more cacti were discovered, it was realized there should be more than one genus for them. Soon the columnar ones were transferred into genus Cereus (Latin for candle), and the globular ones to Echinocactus (Greek for spiny). Soon even more genera were named and described to cope with the range of different new cacti being brought back from the New World. Species were transferred from one genus to another due to research or a persons whim, a process that continues to this day. Today there are about 30 to 200 genera, depending on latest studies, and lumping or splitting (see below).

Knowing the correct names of plants allows us to be concise, so Carnegia gigantea is easier to write than "the big cactus that branches from up high that grows in Arizona" and Stenocereus thurberi is easier to write than "the big cactus that branches from the base that grows in southern Arizona/northern Mexico" and there is no confusion.

Plant's names do change. These changes can be due to new research, lumping or splitting (see below), mistakes in following the rules of nomenclature (invalid names) or even an authors whim in a new book.
Much the same way as this months "medical breakthrough" or research may be dismissed months later in new trials or research.
You don't have to change labels on your plant/s when you hear of a name change. Name changes are accepted over time if professional botanists accept the reasoning of authors making changes. If you don't accept the reasoning, you don't have to change, but be aware of these changes so that if someone else speaks of a plant with it's "new" name you can recognise it.

Lumpers are scientists/hobbyists that concentrate on the similarities and tend to group plants more so there are a fewer number of uniquely named plants, where-as Splitters tend to concentrate on the differences and make more uniquely named plants - Somewhere there is a happy medium!! But also remember these divisions are "man" made and nature itself doesn't divide and name plants as such and the boundary between one species/genera and another can be very obscure, hence the reason classifications do change due to research, perhaps one day with highly advanced DNA technology it will be possible to classify (and hence name) plants with absolute certainty once and for all - or perhaps not!

Part of the reason cactus nomenclature is so mixed up is that much of the original work and naming was done by amateurs and hobbyists without proper training. There have been 11,000 published Latin names for cacti, most of which are incorrect, for the "accepted" 1600 species of today.

Knowing that the genera name (Stenocereus) is like a surname, you could say that another Stenocereus species may look similar (large and cereoid), in much the same way Lucy Jones Mother or Daughter may look like her. Although another stenocereus may look different (Stenocereus eruca is prostate and creeps along the ground) somewhere there will be a similarity e.g. the flower or fruit structure.

In the plant kingdom flower and fruit structures were usually much less changeable among similar plants than were leaf, stem, or root structures which can change due to environmental conditions, so it was decided to concentrate on reproductive structures as a means of classifying plants into similar groups. As an aside plants of similarity are more likely to pollinate with each other to form hybrids than completely different genera/families.

An example of how the SAME plant can look DIFFERENT is the Melocactus genus, when first discovered many Melocactus species were described and named, but on closer investigation it turns out that the species within the genera are highly variable (usually means it is a "young" genera in evolutionary terms and hasn't "settled" down to it's final form) and there are a lot fewer species (and more varieties or even forms) than first described. Differences can also be brought on by growing, soil or weather conditions in the locality.

A complete breakdown of the plant kingdom in summary

Seed-bearing plants are divided into two large groups, the gymnosperms (naked seeds) e.g. conifers, cycads; and the angiosperms (vascular seeds.), which have typical flowers and seeds clothed with some kind of fruit. Angiosperms are further divided into monocotyledons, having one leaf (cotyledon) emerging from the seed like grasses, palms, and aloes; and dicotyledons, having two cotyledons, like beans, roses, and cacti (although in highly evolved cacti the cotyledons are hardly visible in seedlings).
Cacti are further distinguished by petals attaching above the ovaries (inferior ovary) , and the presence of the areole, a special structure which may form spines (modified leaves), flowers, or another shoot - found in no other plant family.
A species is all those plants in nature that are able to reproduce with each other because they are similar. An example would be all the saguaros in the world; they are all one species (Carnegia gigantea) and are native to Arizona and found in cactus collections around the world. Other similar cacti (say organ pipes - Stenocereus thurberi) are not that species though they look somewhat similar and also native to Arizona down into Mexico, but are different either by sight or biologically and can't reproduce with each other (or form hybrids if they do).

A breakdown from Kingdom to species level for Stenocereus thurberi
Kingdom: Vegetable i.e. not an animal
Division: Spermatophyta (seed bearers) -phyta
Superfamily: Angiospermae (flowering plants)
Order: Caryophyllales -ales
Family: Cactaceae (Cactus Family) -acaea
Subfamily: Cactoideae -oideae
Tribe: Pachycereeae -eae
Genus: Stenocereus
Species: thurberi

Common name: Organ Pipe Cactus (an unofficial name that may not be specific to that plant)

Further divisions:
Varieties: littoralis (plants are distinguishable by being smaller in size than the "normal" organ pipe)

Additional categories can be added, where needed, into the system above. For example a large genus can be divided up into subgenera, a sub genus into sections and a section into series. Some words such as `kind', `sort' or `group' have no special rank and usually indicate "horticultural" varieties.

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