Too Many Shared Common Names

Too Many Shared Common Names

Common names don't obey either of those rules. I wrote previously about multiple common names for the same plant. That is annoying, because sometimes you don't recognize that someone is talking about a plant you know only because they're using a different common name.

Calthus palustris  Do you call it cowslip or (marsh) marigold?

Nobody regulates common names. That's one of the reasons for scientific names. The rule on scientific names is: each organism has one and only one name, not shared with any other organism. 

I think the same common name for different plant is even more unfortunate. In this day of using words on the internet to learn about things, shared common names lead to at best, time wasted working out which plant you want, and at worst, possible poisoning because one plant with that name is toxic and one isn't. 

another cowslip Primula vulgaris

another marigold, Tagetes sp.

Why do plants have the same common name? 

Lots of reasons. 

One is: they share some character which creates that name. I asked a local man in Jamaica what a plant was called, and he said it was "blueberry." It had blue berries, but it was certainly not the plant I call blueberry (Vaccinium sp.). Likewise, Africa has a buffalo grass Stenotaphrum secundatum which is not the same as the buffalo grass (Buchloe dactyloides) of North America. Both are grasses, and probably both are eaten by buffalo, although the buffalo of Africa (scroll down to Gallery) is different from the buffalo of North America.

What I call blueberry

I grew up calling the plant below mountain ash. Its scientific name is Sorbus americana. In England, a very similar species, Sorbus aucuparia, is also called mountain ash (and rowan). 

mountain ash, Sorbus

But I was surprised in Australia to be told the huge tree below is mountain ash. It is Eucalyptus regnans. Wow! Very different. Maybe both trees reminded settlers of an ash and grew in the mountains. Or...(your explanation here). 

mountain ash, Eucalyptus

A second source of problems seem to be that plants that are vaguely similar get the same name. There are two different groups of plants called coneflowers in the U.S. midwest, purple coneflower (Echinacea species) and prairie coneflower (Ratibida columnifera). As you see below, they are pretty easy to tell apart. Coneflower presumably is a descriptor for having a composite, daisy-like inflorescence (cluster of flowers). I only this summer worked out that both of these plants go by "coneflower": I was getting them mixed up but didn't understand why. 

purple coneflower (Echinacea)

prairie coneflower (Ratibida)

Speaking of daisies, the plant I learned as the daisy, Leucanthemum vulgare, shares its name with Bellis perennis. In the U.S. the former is "daisy" and the latter is the "lawndaisy" but in England the former is ox-eye daisy and the latter is just "daisy." 

oxeye daisy, Leucanthemum vulgare

lawndaisy, Bellis perennis

Probably the greatest cause of duplicate common names, at least in North America and other places settled in the last 500 years, is a plant that reminded the settlers of a European plant. Sages, as in sagebrush in the western U.S., are species of Artemisia in the sunflower family Asteraceae. They were named because they smell like culinary sage, Salvia officialis, mint family Lamiaceae. Calling an American or Australian plant by a European plant name worked fine while each one was on a different continent, but too often both plants ended up in the same place (including, on the internet.)

sage, culinary sage, Salvia officinalis

sage, big sagebrush, Artemisia tridentata

That process of sticking an old name on a new plant seems to have included three different plants in the case bergamot, hemlocks, marigolds, and the yams.

A few identical names appear to have been produced by convergence. They came from some other word and ended alike. That applies to lime trees. Americans assume those are trees upon which citrus fruits, limes, Citrus media, grow. In England, there's a lime tree that is a linden, Tilia europaea. The English don't get confused because citrus trees aren't hardy in England. The two names converged: the name lime for the citrus tree comes from the same root as lemon, from the Arabic name for the fruit (lima). Lime for Tilia apparently evolved from lind, the Old English name, to line and then lime.

lime, Citrus

lime, Tilia

When identical names cause confusion, we get careful about adding a modifier for clarity. No one mixes up pineapples and apples because we never leave the "pine" off of pineapples. Lesser-known plants are more of a problem: roses, primroses and evening primroses are all quite different but unless you know all three plants, you might be tempted to shorten the longer names, which could cause significant confusion. 

I recently tried to talk about the difference between potatoes and sweet potatoes. Sweet potatoes, Ipomoea batatas, are vines related to morning glories. Saying just "potato" for Solanum tuberosum, was uncomfortable right after talking about sweet potatoes, but so was calling them "white potatoes". As sweet potatoes get more common, I may get more comfortable saying "white potatoes" since "Pass the potatoes" is ambiguous if both are on the table and I don't want more sweet potatoes. 

sweet potatoes, Ipomoea batatas

potatoes, Solanum tuberosum

That is how language evolves. When communication is ambiguous, we add a word or two for clarity or use an alternate name. Googling a familiar name may turn up several different plants. If it confuses many people, we'll start clarifying. 

When the scientific name is included, it should identify the plant, but lots of people don't use scientific names when they write.

There are many duplicate and near-duplicate plant common names! Consequently it pays to notice the whole name: the"evening" in evening primrose, "brush" in sagebrush, "wild" in wild bergamot. Those are there so you don't confuse those plants with primroses, garden sage or the bergamot orange. 

References
"lime n2." and "lime n3" OED Online. Oxford University Press, September 2016. Web. 10 November 2016.
Reader's Digest. 1989. Field Guide to the Wild Flowers of Britain. Reader's Digest Association, London. 

Previous blogs about being careful with common names:
What a mess!
Too many common name