Wherefore Art Thou Cactaceae?
What's in a name? Nearly everyone has heard this question and knows it from Shakespeare's play "Romeo & Juliet". We also know that when Juliet
posed that well-known hypothetical question, she used a rose as an example - stating that by any name a rose would still smell the same. But have
you ever wondered why she didn't say "cactus" instead of "rose"?
(OK, you probably haven't.)
However, if you did ponder this thought and
looked into the subject, you'd find that cactus plants originate in the new world. (With
one exception.) This means that these unique plants would not have been very familiar to the
inhabitants of 16th century Europe. That doesn't mean the cactus was entirely unfamiliar to them at that time, but largely so. Christopher Columbus is credited with
bringing the first cactus to Europe on his second trip to the New World in 1495.
Admitting to a lack of supporting evidence, I suspect the Bard probably wanted to
reference cactus instead of roses were it not for one big problem. The term "cactus" was not used the way we use it today. There are reports that the
name "cactus" referred at one time to a spiny plant of the old world, although the identity of this plant is a mystery. Even so, this name wasn't used as a
plant "family" name back then and actually never officially was used as such. But we're getting ahead of ourselves. Let's back up and dig further into the history
of this name-in-question.
The english word "cactus" is derived from the Greek word κακτος or kaktos which means "thistle". Merriam-Webster gives
a date of 1767 for this term. I am assuming that they must be giving the origin date as an English word as the Latin form of the Greek was used by early plant botanists
and even Columbus is believed to use the term Echinomelocactus for his specimen. This name would imply a meaning of spiny-apple-thistle and is obviously an attempt to
describe the odd look of this new plant using old familiar language. Although the sole term "cactus" doesn't appear to have been used until some time later. In the late 1500's
some English gardeners are known to have had cactus plants in their collections. In the meantime, as more and more ships made journeys to and from the America's, more and more
cactus plants were introduced to Europe. This was all before the Linnaean binomial nomenclature that we are familiar with was invented. At that time plants were
described using polynomials or multiple descriptive names. While being more descriptive than the vernacular or common names, they would be difficult to learn and could not
be easily referred to by memory. Here is an example from "The Gardeners Dictionary" of 1754:
CACTUS quinquedecium-angularis rotundus, spinis creberrimis corallinis latis & recurvis. Large Melon-thistle, with fifteen Angles, and broad recurved
Thorns, which are of a red Color.
The above string of Latin words is the polynomial name for what we would today call a species. The english text that follows is the translation of the latin words.
On the bright side, the concept of grouping like organisms was already invented. In the example above, notice that the word "cactus" is in caps and not
italicized. This is what was known as the plant genus. While it is tempting upon hearing that term to define it as the taxonomic rank above "species"
and below "family", we must be careful not to do it. The word genus simply means "a group with common characteristics". This is the sense that it was used in
polynomial taxonomy and it also fits that meaning in binomial nomenclature, but in the polynomial system there is no additional grouping at a "higher" level.
This information is important because we see the term "cactus" being used here as a genus, not as a family. Initially, "cactus" was used
not on its own, but as the genus Melocactus. As mentioned above, the term Echinomelocactus was used, but not as an official genus. The shorter Melocactus was preceeded
by Cereus, Opuntia, and Pereskia, making four separate genera with Melocactus being the latest of these names.
Enter Carl Linnaeus; famous to this day as the inventor of binomial nomenclature, a system still used over 250 years later! Previous to this invention, however, Linnaeus
followed the existing system of polynomial taxonomy. It is in this way that he first treated cactus species placing them in two groups (genera). These were "Cactus" and
"Pereskia". This was in the 1737 work Hortus Cliffortianus and was after the terms Melocactus and Pereskia were already used by earlier naturalists.
It is Linnaeus, however, who gets the credit for shortening the term "Melocactus" to simply "Cactus". Species Plantarum is the 1753 work
where Linnaeus introduced binomial nomenclature as-we-know-it to the world. At that time 22 species of cactus were known and Linnaeus decided to put them all under a single genus,
Cactus. This is where Phillip Miller got the term that he used in "The Gardeners Dictionary" referenced above. He thus used Linnaeus' term, but with the old polynomial
system and not the binomial system that had just been invented. It is important to note that Miller also didn't include all known species under this single genera, but also included three other
genera: Cereus, Opuntia, and Pereskia.
Back to Linnaeus - we must note that he still used the term "Cactus" only as a genus and not as a family in his new system. It was Antoine Laurent de Jussieu that grouped cacti
together under the family name we know today, that is, the Latin name, "Cactaceae". This was in 1789 and this name is still used today as the official family name
despite a great deal of naming and renaming below this classification level since then.
If you have been able to follow me through this, you'll note that the name "cactus" was never used as a family name for this group of plants and it is no longer used
as a genus name. So what do we make of the word "cactus"? Is it proper to refer to the Cactaceae as "The Cactus Family"? The answer is "Yes!"
This is despite whatever you might have been told by some pedantic hothead on a web forum somewhere. If you are not publishing an official taxonomic description of a plant, then
using the English words, "cactus", "cacti", or "cactuses" are all perfectly appropriate. Most ordinary people have no qualms about using the singular
"cactus", but I have been asked several times which plural form is correct. For this you can use any of the terms - including "cactus" - which can be singular and
plural both. I happen to prefer using "cactus" for singular and "cacti" for the plural because I think it sounds the best. To me, saying "I like to grow
lots of cacti." simply sounds better than "I like to grow lots of cactus.", but either would be appropriate. And just because I know that students of the Latin
language are likely to object, I will point out that the Latin terms have been transliterated into English and despite the same spelling, they are now English words and
not Latin words. So those formal Latin rules don't apply. And when checking an English dictionary, we get a great big thumbs up on using any of these terms.
So after all that, my gut tells me that our friend Shakespeare probably loved cacti - he was a smart guy after all. Yet, knowing his audience, he opted for the Rose
analogy over the term "Echinomelocactus". But certainly there was a pause of the pen as he wrote it - there must have been!
Author: Daiv Freeman