Smooth Beardtongue, Foxglove Beardtongue, Foxglove Penstemon

Penstemon digitalis

PEN-stem-on  dig-ee-TAH-liss

Synonyms of Penstemon digitalis (8) (Updated on 12-21-23 from Plants of the World Online): Chelone digitalis (Nutt.) Sweet, Penstemon alluviorum Pennell, Penstemon digitalis var. albidus Trautv., Penstemon digitalis f. baueri Steyerm., Penstemon digitalis var. latifolius Regel, Penstemon laevigatus subsp. alluviorum (Pennell) R.W.Benn., Penstemon laevigatus subsp. digitalis (Nutt.) R.W.Benn., Penstemon laevigatus var. digitalis (Nutt.) A.Gray

Penstemon digitalis Nutt. ex Sims is the accepted scientific name for this species of Digitalis. It was described as such by John Sims in the Botanical Magazine in 1825. Mr. Sims gave credit to Thomas Nuttall for previously naming and describing the species… 

Plants of the World Online previously listed the scientific name as Penstemon digitalis Nutt. That would mean Thomas Nuttall was the first to name the species in Transactions of the American Philosophical Society in 1835. I sent the editor of Kew an email, like I always do when notice there is an issue, and he sent a link to the publication. Mr. Sims wrote in 1825 after the description:

“Communicated by our friend Robert Barclay, Esc. to whom the seeds were sent by Professor Nuttall, in March, 1824, under the name we have adopted, thinking is probable, that it may have been published but it in America; otherwise a substantive specific name should be confined to such species as have before constituted a different genus. A hardy perennial. Native of the Arkansa territory…”

Mr. Nuttall wrote The Genera of North American Plants, in two volumes in 1818. I read through both editions and Penstemon digitalis is not mentioned. Afterward, in 1835, Mr. Nuttall wrote about the species in Transactions of the American Philosophical Society, which there were many volumes published. I haven’t read through any of those yet to see what he said. The species had to have been named AND described prior to 1824 for him to have sent seeds with the name Penstemon digitalis… Well, likely, he named the species but it just wasn’t published. I guess he goofed so he didn’t get full credit. 

According to what I have read thus far, Mr. Nuttall (who was an English botanist) was on an expedition from 1818 through 1820 traveling along the Arkansas and Red Rivers. After returning to Philadelphia, he published a book about the expedition in 1821. In 1825 he became the curator of the botanical garden at Harvard. He resigned his position and went on another expedition in 1834 and didn’t return home until 1836… SOOOO…. He wrote the description for Penstemon digitalis in Transactions of the American Philosophical Society in 1835 while he was on an expedition? Hmmm… 

Lewis and Clark and previously collected samples of plants of which many were lost. Some of the specimens Nuttall collected on his expeditions were likely the same as the ones that were previously lost and even possibly named by Meriwether Lewis. The problem is, a name and description have to be accompanied by specimens (in one form or another) to make the name legit.

I also read where Nuttall sent seeds and the description for Penstemon digitalis home to England in 1824, which was later “re-published” by Mr. Sims in Botanical Magazine in 1826, after the seeds grew and the plants flowered (so he could have proper specimens no doubt)… I read that Nuttall “didn’t have time” to publish his description himself until 1835 because his work on “this species” was incomplete… Hmmm… How could he have time?

The genus, Penstemon Schmidel, was named and described as such by Casimir Christoph Schmidel in Icones Plantarum in 1763.

As of 2-21-23 when this page was last updated, Plants of the World Online lists 281 species in the Penstemon genus. The genus is a member of the plant family Plantaginaceae with a total of 107 genera. Those numbers are likely to change as updates are made by POWO.

The above distribution map of Penstemon digitalis is from Plants of the World Online. Areas in green are where the species is native and purple is where it has been introduced. The map on the USDA Plants Database for the United States and Canada is the same. The species may be more widespread than what the maps show.

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations.

THERE ARE SEVERAL LINKS FOR FURTHER READING AND MORE PHOTOS AT THE BOTTOM OF THE PAGE. 

Penstemon digitalis is a perennial wildflower that attracts several species of insects. I don’t have this species growing on my farm, but I found a few fairly large colonies growing along a highway close to town. It was quite a sight.

Plants grow to 3’ tall, more or less, on stems that are mostly hairless (glabrous). The leaves grow in an alternate pattern along the stems and sometimes in whorls of three. Leaf shape is variable but are mostly lance-shaped.

The white flowers are tube-shaped and the corollas are divided into a lower lip with 3 lobes and an upper lip with 2 lobes. The flowers of the colony I was photographing had all white flowers but they can also be splashed with purple. If I had have checked every plant I may have found some with streaks.

I first identified this species as Penstemon tubaeflorus, but a member from iNaturalist suggested they were P. digitalis. The lobes on P. tubaeflorus flowers are closer together than those of the P. digitalis otherwise they are pretty much alike. I am sure there are other characteristics that separate the two species if you want to get down to the nitty-gritty.

While wildflower hunting on a friend’s farm on May 10 in 2020 I ran across this plant that was not in flower yet. I took photos anyway and planned to go back when it was in flower to identify it better. I was unable to go back, but an amazing thing happened later and I was able to identify this plant as Penstemon digitalis.

The Foxglove Beardtongue emerges in the spring with a rosette of long lance-shaped basal leaves. Soon it will start sending up a stem that can grow up to at least 3’ tall. The stems are usually glabrous (hairless) but can also have small hairs toward the tip. Information suggests basal leaves persist even after the stem leaves fall off and the fruit goes to seed in the fall.

Both basal and stem leaves grow in an opposite arrangement along the stems. The leaves vary in shape from broadly lanceolate, ovate, obovate, spatulate, and rounded too bluntly or sharply pointed at the tip. The longest leaves can be up to at least 6” long and 2 1/2” wide and may have a slightly reddish tint.

The leaves taper slightly toward the base. I think the basal leaves may have winged petioles whereas the upper leaves are sessile (without petioles), sometimes shallowly cordate (triangular) and clasping (around the stems). Th leaves of the plants I observed and photographed had small teeth along the margins but they can also be smooth. Like I said, the leaves are quite variable…

The above photo shows a good close-up of the stem that has very short hairs. Sometimes the hairs appear to be growing in lines…

On June 14 (2020) I decided to take a walk to the back of the farm even though the grass was very tall for hay. Lo and behold, I found a single Penstemon digitalis not far after entering the back section. I have been here since 2013 and this was the first time I had seen one here on this farm. It makes me wonder how it could have got here all of a sudden.

It always amazes me how I can be wildflower hunting and find a single plant of a species and none anywhere else to be found… The above photo shows a flower with reddish streaks…

Then, as I walked toward the southeast corner of the farm I noticed white flowers from a distance. HOLY COW! There was an entire colony! Until 2017 cows always grazed this lower section. In 2017 and 2018 I cut hay here about July. I don’t normally walk through the hayfield because the grass becomes very thick and tall and it is hard to walk through. Still, it is weird they are here right under my nose and I didn’t know it…

I didn’t have to go anywhere this year besides my own farm to take more photos of this plant but I do need to go back and get some close-ups.

The above photo shows leaves that grow in opposite pairs with small teeth along the margins that are sessile (no petioles) that clasp the stem. Pretty neat, huh?

Penstemon flowers attract a variety of long-tongued bees and butterflies which help with pollination.

There are more photos from 2021, 2022, and 2023 below the links.

I have enjoyed photographing and learning about the many wildflowers growing on the family farm and in other areas. The farm is in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 250 species of wildflowers (most have pages listed on the right side of the page). I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a few horticulturalists I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
FLORA OF NORTH AMERICA (GENUS/SPECIES)
FLORA OF MISSOURI (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
MISSOURI BOTANICAL GARDEN
MISSOURI PLANTS
iNATURALIST
WILDFLOWER SEARCH
DAVE’S GARDEN
USDA PLANTS DATABASE
ILLINOIS WILDFLOWERS
MINNESOTA WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
GO BOTANY
LADY BIRD JOHNSON WILDFLOWER CENTER
FLORA FINDER
FRIENDS OF THE WILDFLOWER GARDEN

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands (some over a million) of species to keep up with. Accepted scientific names change periodically and can be hard to keep with. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂

PHOTOS FROM 202, 2022, AND 2023.