JARS v61n4 - The Word: Macrophyllum

The Word: Macrophyllum
Bruce Palmer
Cutten, California

Bruce Palmer begins his series The Word, which will explore origins of botanical terms and other subjects of interest to serious gardeners.

The word for this journal issue is "macrophyllum." It is from two Greek words, "macron" for long (alternatively, large) and "phyllon" for leaf. We are all familiar with the word from our North American West Coast native Rhododendron macrophyllum . It seems like a good current word to deal with given the fantastic display the species put on this past spring in the woods surrounding Florence, Oregon, City of Rhododendrons, as the town celebrated the hundredth anniversary of its rhody festival and the Siuslaw Chapter hosted a stunning district-wide flower show. Their newsletter is clearly entitled to be named Macrophyllum.

R. macrophyllum</em> 'Albion Ridge'
Rhododendron macrophyllum 'Albion Ridge' . The first description of the species in 1834
may have been from a white form (Leach, D., Rhododendrons of the World, p. 189).
Photo by Eleanor Philp, courtesy of Dick Jones.

There are some interesting ideas related to the name of this plant. Let's look first at why every plant has two scientific names, genus and species. Carl von Linné, the man we know by his Latinized name, Carolus Linneaus, is responsible. This year is the 300th anniversary of his birth. In the eighteenth century, European scientists were struggling to make sense of the natural world as specimens flowed in from the great voyages of exploration. Because there were so many languages in Europe, scientists, many of whom were clergy, used the universal language of the church, Latin, to communicate ideas to each other. Naturalists several generations before Linnaeus began to give plants long descriptive Latin names. The wild rose was named Rosa sylvestris alba cum rubore, folio glabro and catnip was called Nepeta floribus interrupte spicatus pedunculatu s, to name but two common examples. By the time of Linnaeus, this cumbersome system had gotten completely out of hand. The lasting contribution he made to biology was the establishment of a system of relationships culminating in a two-word name. Each organism has a double Latinized name called a binomial that distinguishes it from all others. Linnaeus renamed the wild rose Rosa canina and catnip Nepeta cataria . The binomial nomenclature of Linnaeus has lasted through time, but he bequeathed us one troubling legacy. For obscure reasons, he decided that the best way to distinguish organisms was by their reproductive parts. Flowering plants are still distinguished this way, making it particularly difficult to identify them in plant manuals if they are not in bloom. The problem isn't unique to us. The father and son botanists Forster on Captain Cook's second voyage were unable to identify many of the plants in New Zealand in 1773 because it was winter and the flowering season was over. The system has its flaws, but it has stood the test of time and works quite well for us today.
The second reason to wonder about the name is why it is now called Rhododendron macrophyllum and not Rhododendron californicum as it was from 1855 until the 1950s. The rhododendron part is easy. From the Greek for "rose tree," it was named that by Linnaeus. When the famous botanist J. D. Hooker, in about 1855, was working on specimens from Vancouver's late eighteenth century expeditions to the Northwest Coast, he named a pressed specimen R. californicum . That name was used until the middle of the last century and is still listed as a synonym in flowering plant manuals. Linnaeus foresaw this kind of name conflict and established a rule of priority. If an organism is given a name and it is later found to have been named earlier by someone else, the earlier name must be used. A specimen of this species had been described by the Don brothers of Cambridge University and the Linnaean Society in England in 1834 as Rhododendron macrophyllum . Therefore, under the International Code of Botanical Nomenclature, the name as we know it now was properly established at least two decades earlier than Hooker named it. The West Coast native rhody named R. macrophyllum can't compete for leaf size with later discoveries such as R. macabeanum , but that's beside the point; the North American species had the name first.

Bruce Palmer is a member of the Eureka Chapter. He was a teacher of biology at Maui Community College in the University of Hawaii System for twenty-five years.