You don’t have to be very sharp to recognize that Spanish cacto means the same as English cactus. Nevertheless, if Gertrude Stein, speaking of a different plant with showy flowers that also warrants careful handling, wrote that “A rose is a rose is a rose,” people who delve into etymology and botany can say that “A cactus isn’t a cactus isn’t a cactus.” For the Romans, the word cactus referred to a cardo/cardoon, which is a thistly relative of the artichoke that people cultivate for its edible root and petioles [leaf stalks]. The Romans had taken cactus from Greek kaktos, which designated a certain prickly plant found in Sicily that is now called an alcachofa española/Spanish artichoke.
To transfer a word from an artichoke to a cardoon wasn’t much of a stretch, but how did cacto/cactus come to designate the different sort of plant we know by that name today? The answer is that Linnaeus, the great categorizer of modern botany, mistakenly believing that cacti, with their spines, are related to thistles, with their prickles, recycled the ancient thistle-related Latin word as a name for what later turned out to be an unrelated family of plants. By then the modern sense of cacto/cactus had become firmly established, and we have been stuck with [or by] it ever since.
© 2010 Steven Schwartzman