Triodanis perfoliata (Clasping Venus’s Looking Glass)

Triodanis perfoliata (Clasping Venus’s Looking Glass) on 6-12-22, #890-51.

Venus’s Looking Glass, Venus’ Looking Glass, Clasping Bellflower

Triodanis perfoliata

try-oh-DAY-nis  per-foh-lee-AY-tuh

Synonyms of Triodanis perfoliata (5) (Updated on 12-13-22 from Plants of the World Online): Campanula perfoliata L., Legousia perfoliata (L.) Britton, Pentagonia perfoliata (L.) Kuntze, Prismatocarpus perfoliatus (L.) Sweet, Specularia perfoliata (L.) A.DC.
Synonyms of Triodanis perfoliata subsp. biflora (18) (Updated on 12-18-22 from POWO): Asyneuma anhuiense B.A.Shen, Campanula biflora Ruiz & Pav., Campanula intermedia Engelm. ex Nutt., Campanula ludoviciana Torr. ex A.Gray, Campanula montevidensis Spreng., Dysmicodon californicum Nutt., Dysmicodon ovatum Nutt., Heterocodon minimum Kellogg, Legousia biflora (Ruiz & Pav.) Britton, Lobelia humboldtiana Schult., Pentagonia biflora (Ruiz & Pav.) Kuntze, Specularia biflora (Ruiz & Pav.) Fisch. & C.A.Mey., Specularia californica (Nutt.) Vatke, Specularia ovata (Nutt.) Vatke, Specularia perfoliata f. ramosa Arechav., Specularia perfoliata f. rigida Arechav., Triodanis biflora (Ruiz & Pav.) Greene, Triodanis perfoliata var. biflora (Ruiz & Pav.) T.R.Bradley
Synonyms of Triodanis perfoliata subsp. perfoliata (autonym) (10) (Updated on 12-18-22 from POWO): Campanula amplexicaulis Michx., Campanula angulata Raf., Campanula anticensis Kunze ex A.DC., Campanula flagellaris Kunth, Campanula verticillata Hill, Dysmicodon perfoliatum (L.) Nutt., Specularia perfoliata f. alba (J.W.Voigt) Steyerm., Triodanis perfoliata f. alba J.W.Voigt, Triodanis rupestris Raf., Triodanis scabra Raf.

Triodanis perfoliata (L.) Nieuwl. is the accepted scientific name for this species of Triodanis. It was named and described as such by Julius (Aloysius) Nieuwland in American Midland Naturalist in 1914. It was previously named and described as Campanula perfoliata by Carl von Linnaeus in the first volume of the first edition of Species Plantarum in 1753.

Accepted Infraspecific Names (2) (updated on 12-28-21 from POWO): Triodanis perfoliata subsp. biflora (Ruiz & Pav.) Lammers, *Triodanis perfoliata subsp. perfoliata (autonym). *When an infraspecific taxon is named, an autonym (“type-specimen”) is automatically generated whose description is closest to the (original) species. All have their own list of synonyms…

Triodanis perfoliata subsp. biflora  (Ruiz & Pav.) Lammers is an accepted subspecies of Triodanis perfoliata. It was named and described as such by Thomas G. Lammers in Novon in 2006. It was previously named and described as Campanula biflora by Hipólito Ruiz López and José Antonio Pavon in Flora Peruviana, et Chilensis in 1799. Some authorities do not recognize this taxon as a separate species. The two are quite similar and it has to do with their flower types (reproduction) from what I have read. You can read about it by clicking HERE

The genus, Triodanis Raf., was named and described by Constantine Samuel Rafinesque in New Flora and Botany of North America in 1838.

As of 12-18-22 when this page was last updated, Plants of the World Online by Kew lists 6 species in the Triodanis genus. It is a member of the plant family Campanulaceae with 94 genera. Those numbers could change as updates are made on POWO.

Distribution map of Triodanis perfoliata from Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; Retrieved on May 24, 2021.

The above distribution map for Triodanis perfoliata is from Plants of the World Online. Areas in green are where the species is native and purple are where it has been introduced. You can view the map for Triodanis perfoliata subsp. biflora by clicking on the link to POWO. The map on the USDA Plants Database for the United States and Canada is similar but doesn’t include the state of Nevada. The USDA doesn’t list lower taxon for this species.

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.  


Triodanis perfoliata (Venus’s Looking Glass) on 6-14-20, #710-59.

I was walking along the edge of the back pasture on June 14 in 2020 and stumbled upon a neat plant I hadn’t noticed before. It was only 6-8″ tall and it would have been very easy to overlook growing in tall grass. Unfortunately, there were no flowers left, just remains of what was. The light green, rounded, clasping leaves were enough to identify the species as Triodanis perfoliata commonly known as the Clasping Venus’s Looking Glass.

Triodanis perfoliata is a native annual species. Although it can be found throughout Missouri and all across the United States, it is a very small plant that can easily be overlooked. It is easily identified by its clasping leaves and small flowers that grow all along the stem. The Missouri Plants website indicates there are five species of Triodanis in Missouri, and some are quite similar. The major difference, of all things, is the position and shape of the fruit pore…

A common trait of the genus is that the plants produce both normal flowers and cleistogamous (self-pollinating) flowers that stay closed.

Triodanis perfoliata prefers growing in full sun in fairly moist to slightly dry soil. But that isn’t always the case. It seems to grow its best in poorer, sandy soil. One thing it doesn’t like is too much competition from taller plants, although I have seen them growing under blackberry briars. The first time I found this plant, it was growing among trees in a fence row where it only received morning sun.

There are a few more photos at the bottom of the page under the links for further reading.

Triodanis perfoliata (Clasping Venus Looking Glass) on 6-15-21, #800-33.

On May 24 in 2021, I walked to the back of the farm to the location I found the Triodanis perfoliata in 2020. Unfortunately, there were none to be found. My camera shot craps, so I wasn’t able to go wildflower hunting again until I bought a new one. Once it arrived, I went out again on June 15. As I was crossing the fence from the southeast corner of the farm to go to the south hayfield, I looked down and saw a single Triodanis perfoliata. In the shade of other plants! Unfortunately, it had no flowers either. It was already almost 8:30 PM…

Triodanis perfoliata (Venus’s Looking Glass) on 6-14-20, #710-60.

Plants usually have a single stem and generally grow no taller than about 18”. The light green stems, 4-5 angled, with deep grooves, slightly rough with short recurved hairs along the ridges.

Triodanis perfoliata (Clasping Venus Looking Glass) on 6-16-21, #801-82.

On June 15 after I took a few photos of the Triodanis, I walked along the south side of the south hayfield and took several more photos. The light was brighter in that area, so I got a few more shots before walking back to the house. It became so dark the photos of a few species had to be retaken. So, on the 16th, I went back to the south hayfield. I looked down after entering the area and HOLY CRAP! There were A LOT of Triodanis perfoliata, and some still had flowers!!!

The leaves grow in an alternate manner along the stems that reminds me of a spiral staircase. There is supposedly a pair of opposite leaves at the top of the stem, but I haven’t noticed that. Actually, I didn’t know about it until I wrote descriptions. Imagine the things we learn when we read. 🙂 The basal leaves are described as broadly elliptic, broadly ovate, or cordate (heart-shaped) with a rounded or bluntly pointed tip. Upper leaves are slightly narrower, broadly ovate, or kidney-shaped. All the leaves clasp the stem, which is pretty neat, and have blunt to sharp teeth along the margins. The upper surface of the leaves may be glabrous (hairless) or may have tiny hairs, usually along the margins. The undersurface may be roughened with fine hairs, or have soft short hairs. The stems and leaves produce a milky sap.

Triodanis perfoliata (Clasping Venus’s Looking Glass) on 6-12-22, #890-52.

The flowers are produced, 1-3 per node, along most of the length of the stems. Ummm… You have to take a closer look because this species produces both cleistogamous (self-pollinating) and chasmogamous (regular) flowers. In fact, most of its flowers are self-pollinating.

The normal flowers are produced, 1 per node, in the upper 1/3-2/3 of the stem. The flowers are approximately 1/2” wide or wider and are surrounded by a calyx tube that is narrowly triangular and slightly inflated. The 5-lobed corollas are fused at the base to form a short tube and can be purplish blue, purple, pinkish-purple, or pale lavender, with purplish streaks. They are rarely with white streaks or completely white. 

The cleistogamous flowers, surrounded by a 3-4 lobed calyx, the corollas weird and reduced to just short flaps of tissue and never open. The stamens and style are not functional. Fertilization occurs within the flower… I think the flowers on the lower part of the stem, and 2 out of 3 of the flowers on the upper nodes are all self-fertile. One website said only one flower per node is open at a time, which is likely because the others are self-fertile and won’t open at all. Hmmm… 

Only a few of the normal flowers are open at a time, so by the time flowers are open at the upper nodes, there will be fruit at the lower nodes. In Missouri, plants bloom from April through June, depending on where you live. 

As I mentioned previously, the weird fruit is one way to distinguish this species from the others in the genus. 

Triodanis perfoliata (Clasping Venus’s Looking Glass) on 6-12-22, #890-50.

Once flowers fade, the ovaries turn into oval 3-sectioned fruit. If you examine closely with magnification, you can see a thin spot on each section which will open an oval pore for the seeds to be disbursed. Other species in the genus have a narrow slit instead of it being oval… GEEZ! 

The above photo was taken on June 12 in 2022 while wildflower hunting along the Rock Island Spur of the Katy Trail. The trail runs along the south side of the farm and Farrington Park is on the other side of the trail. I spotted a few Triodanis perfoliata that wanted to be photograph. I gladly obliged…

Once these plants bloom and produce seeds, they will just completely disappear. 

Gets its common name from a similar looking plant called Legousia speculum-veneris (Looking Glass, European Venus’ Looking Glass, Large Venus’s Looking Glass) whose seeds are shiny as a looking glass. It is native to several European countries.

I hope to be able to find this species again in 2023. I need more and better photos. I would like to find them in several stages and do a better job at taking close-ups. I need photos to go along with the descriptions Practice makes perfect. 🙂

Don’t forget, there are several more photos at the bottom of the page.

I have enjoyed photographing and learning about the many wildflowers growing on the 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 I would enjoy hearing from you especially if you notice something is a bit whacky.


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 of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. 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 the most reliable and up-to-date plant database and they make updates on a regular basis. 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. 🙂



Triodanis perfoliata (Venus’s Looking Glass) on 6-14-20, #710-61.


Triodanis perfoliata (Venus’s Looking Glass) on 6-14-20, #710-62.


Triodanis perfoliata (Clasping Venus Looking Glass) on 6-15-21, #800-34.


Triodanis perfoliata (Clasping Venus Looking Glass) on 6-15-21, #800-35.


Triodanis perfoliata (Venus’s Looking Glass) on 6-16-21, #801-83.


Triodanis perfoliata (Venus’s Looking Glass) on 6-16-21, #801-84.


Triodanis perfoliata (Clasping Venus Looking Glass) on 6-16-21, #801-86.


Triodanis perfoliata (Clasping Venus’s Looking Glass) on 6-12-22, #890-49.


Please leave a comment. I would like to hear from you.

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.