ENHS Nature Trails December 2002 Article 2

Natural History and You - The President's Forum
by Dave Wagner

Signs of the Season

I have been asked on a number of occasions to give an opinion regarding the correct scientific name for the state flower of Oregon, the Oregon grape. Some sources list it as Berberis aquifolium and others as Mahonia aquifolium.

With Berberis vs. Mahonia, what name one uses depends on the purpose for the name. If what's needed is something that reflects current biological thinking, use Berberis. If one wants to use Mahonia as a biological entity, then Berberis would have to be broken up into small groups and the genus Berberis would lose its usual meaning. If you need something that people think of when gardening, and they don't give a hoot about biology, then use Mahonia.

The situation is similar to that with frogs vs. toads, rhododendrons vs. azaleas, and birds vs. reptiles. When people know only a few representatives of large groups, they like to try to divide them into two big, neat piles. However, when detailed studies of these groups are done, it is sometimes found that the situation is somewhat more complicated.

There is no natural division between frogs and toads; rather there are many groups of tailless amphibians. Some of the things that people want to call frogs are more closely related to things they want to call toads than they are to other things they would call frogs. As one herpetologist told me, all toads are frogs but not all frogs are toads. It would be better from a biological standpoint to call them all aneurans and don't use the terms toad or frog.

Rhododendron and Azalea are not natural genera. Even horticulturalists now appreciate that there are several groups in the genus Rhododendron that combine various traits of what were traditionally used to distinguish Rhododendron from Azalea. So we now keep all of them in a large genus Rhododendron--botanically, that is. In popular language we still talk of an azalea (deciduous, usually 5 stamens) as a different kind of plant than a rhododendron (evergreen, usually 10 stamens). This difference means something to a landscape designer that satisfies a need to describe a particular type of garden element.

And the same thing is true of birds and reptiles, perhaps the hardest to accept. The fossil record makes clear that there is a group of reptiles that includes the birds and then there are other groups of reptiles that are less related to the bird-like ones. So strong is the historical, intuitive sensibility, that in popular usage people will continue to separate birds and reptiles even though birds are, from a biological standpoint, a group of feathered reptiles related to dinosaurs. Crocodiles and most dinosaurs are more closely related to birds than they are to snakes or turtles.

Likewise, botanists recognize that what is called Mahonia refers to a group of plants that fall within the bounds of a natural group that must be called Berberis (based on the priority rule of botanical nomenclature). Horticulturists will persist in using the name Mahonia because it describes a particular ornamental trait regardless of biological relationships. I don't think this usage matters too much, any more than it does that people continue to think of birds as separate from reptiles, or azaleas as different from rhododendrons.

There is no such thing as an Official International Registry of Botanical Names. The International Code of Botanical Nomenclature tells one how to use a name and how to determine if it is valid when used in a particular way. Coming up with what name to use is left up to the scientist or name user: It's called a taxonomic decision. So long as the name follows the rules of nomenclature, it can be considered correct. If I want to treat the monotropoids (candy stripe, pine drops, Indian pipe, etc.) as a separate family, Monotropaceae, that's my taxonomic call. Monotropaceae is an accepted, valid name. Somebody else is just as correct (nomenclaturally and biologically) to say the monotropoids represent a subfamily of the Ericaceae and call them by a subfamily name, Monotropoideae. As my taxonomy professor used to say, "There is no objective means of determining rank in a hierarchy."

The closest thing to an authoritative list is the Plants Database (Kartesz is the main author) maintained by the U.S. Department of Agriculture. The internet address for the site is:

http://plants.usda.gov

Many federal agencies require their people to use this list for consistency. It is worth noting that the Plants Database uses Mahonia rather than Berberis.

However, remember what Ralph Waldo Emerson said, "A foolish consistency is the hobgoblin of a small mind." The purpose of names is for our convenience; naming is not science. It is nice when names reflect current biological thinking, but there is no consensus visible in the future because our system of naming doesn't exactly match evolutionary processes.

[ Back ]

Page last modified: 20 January 2003
Location: http://biology.uoregon.edu/enhs/archive/dec02/dec022.html
E-mail the WebSpinner: cpapke@gmail.com