Disambiguation of Plant Names: Goat's Beard, Indian Paintbrush, Coneflower, and Yucca

More than a few plants share a common name. Sometimes the plants are similar, sometimes very different. Following a previous disambiguation blog (link) I'll bring some more of those to your attention so you remember to be careful to check which plant is being called by that name. In this post: goat's beard, Indian paintbrush, coneflower, and yucca. 

Indian paintbrush, Castilleja species

Goat's beard. I grew up calling salsify, Tragopogon species (sunflower family Asteraceae) goat's beard. That is a common common name for it in Europe, where the tragopogons are native, referring to the long white hairs on the seed head. Also called goat's beard is Aruncus dioicus (rose family, Rosaceae) a native American shrub. Aruncus's flowers also look like a goat's beard, but are very different from Tragopogon. Both have alternative common names, Tragopogon is also called salsify, Aruncus is called bride's feathers.

goat's beard, Tragopogon

goat's beard, Aruncus dioicus, American native

Neither is called goat's beard by the USDA plants database.

Indian paintbrush. In my childhood in New York, Indian paintbrush was the name of red-orange or bright yellow-flowered Hieracium species (sunflower family, Asteraceae). You can see (below) how they look like little paintbrushes. Across the western U.S., though, Indian paintbrush is the common name of Castilleja species in the owl clover family (Orobanchaceae). The many species of Castilleja have flowers in colors from white to green to deep red and purple. They are native to the western half of the U.S. The many colors of their flowers as well as the way they look "paint-covered" in the grass (second photo below, first photo in this blog) explain calling them Indian paintbrushes. As far as I know, the Castilleja species have only Indian paintbrush or paintbrush as their common names, but Hieracium, from Europe, is also known as hawkweed. Hieracium species are troublesome invasive species. American sources today call Castilleja Indian paintbrush and Hieracium hawkweed.

Indian paintbrush, Hieracium, also called hawkweed

Indian paintbrush, Castilleja species

Coneflower. Plants in the sunflower family (Asteraceae) have a series of small flowers clustered together (disc florets) with other specialized flowers surrounding them providing petals (ray florets). Several plants of central North America have their disc florets pressed together so they look like a cone. People call plants in the genera Echinacea, Ratibida, and Rudbeckia "coneflower," which can be quite confusing. It is rather common for members of the same genus to go by the same common name (Taraxacum species are dandelions, most Helianthus species are sunflowers.) There are no rules on common names so Ratibida can be coneflower as well as Echinacea. But if you have a picture of Echinacea as coneflower in your mind, when someone hands you Ratibida, it is a surprise. Echinacea is usually formally called "purple coneflower" but plant breeders have produced pink and white Echinacea varieties (at least), so the color isn't definitive. And people tend to drop the adjectives. Echinacea is also called echinacea as a common name, which limits that name to a genus of about nine very similar species.  

purple coneflower, Echinacea

Ratibida species are called "prairie coneflowers." Prairie is not really very helpful since all thes coneflowers cone flowers grow in American prairies.  The cone is certainly obvious (below).

coneflower, Ratibida

As you go south into Oklahoma and Texas, prairie coneflowers become two-toned. These are often called Mexican hats. They are the same species as prairie coneflower, that is, Ratibida columnifera. 

Ratibida columnifera, prairie coneflower or Mexican hat

Rudbeckia hirta black-eyed susan, coneflower

Rudbeckia. There are some 25 species of Rudbeckia native to North America. Two are called blackeyed Susan (Rudbeckia hirta) and browneyed Susan (Rudbeckia triloba), but all the rest are coneflowers: orange coneflower, western coneflower, showy coneflowar, Klamath coneflower, cutleaf coneflower... There's a cone but its not particularly dramatic. I have no photos of Rudbeckia coneflowers other than R. hirta, but looking up photos of them (see USDA plants and Google), several look very much like blackeyed Susans, others have fewer or floppier petals (ray florets) though are otherwise very similar.   

The botanical synonyms listed by the USDA Plants data base suggests all the coneflowers were called Rudbeckia initially and then Echinacea and Ratibida were separated out and renamed, so they all come by the coneflower name from history. 

Yucca and yuca

These names are not actually the same, but are similar enough to be very confusing. Yucca is the scientific name of a group of plants of the southwestern United States into Central and South America.  They are in the asparagus plant family Asparagaceae and, while they have useful properties, are generally cultivated, if at all, as ornamentals. The flowers are edible but almost no one eats them. Common name for the northern-most one, is small soapweed (Yucca glauca), referring to the saponins in the roots that make it genuinely soapy. Other species grown in the southern U.S. are often called Spanish bayonets. In warm regions, some Yucca species are tree-like, for example the Joshua tree, Yucca brevifolia. Yucca is often used as a common name for Yucca species, especially lesser-known ones,  since yucca is an easy word. 

Yuca is a common name for Manihot esculenta in the spurge family, Euphorbiaceae. It is properly pronounced with a long "u": "you ca" while yucca is "yuck a" but of course that can vary. Widely grown across the tropics for its starchy roots, yuca is also called cassava and manihot. It does not grow outside the tropics. I included two photos below wanting to show this is a 5' or taller shrub with a woody trunk and broad flat leaves, not a cluster of sharply pointed leaves on the ground or all along the stem. 

Yucca glauca, small soapweed

Joshua tree, Yucca brevifolia. 

yuca, cassava, manihot, Manihot esculenta
the inflated roots are the source of cassava

yuca, cassava, manihot, Manihot esculenta
top of the plant: very different from Yucca

You eat yuca not yucca. 

The USDA plants database gives the Yucca species the common name yucca and Manihot the common name cassava. 

Common names are local names and are just fine if everyone knows what you mean. They become problematic when people talk across each other, referring to different plants by the same name.  

"Goat's beard is an awful weed, eradicate it." (Referring to a  Tragopogon)

"No it isn't, goat's beard is a lovely native, you should plant it." (Referring to Aruncus)

I don't think we can prevent the growth and spread of confusing common names. Furthermore, the more we interact with Australia, India, and other places that speak English but have different familiar plants, the more chance of misunderstanding duplicate common names. Scientific names were invented to deal with that problem, each plant species has a unique scientific name. Too often people don't bother with the scientific name, but including it somewhere (in your talk, on your website, in your request to a plant nursery) will prevent a lot of miscommunication.

And, knowing there are some quite different species with the same common name will help you watch for confusion.

Comments and corrections welcome.

Blogs I wrote that discuss these species

Tragopogon salsify

Hieracium hawkweed

Castilleja Indian paintbrush

Echinacea and Ratibida link

All three coneflowers link

Yucca Small soapweed. link

Kathy Keeler, A Wandering Botanist 
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