TWO RUE-ANEMONIES
Rue Anemone: Thalictrum thalictroides (thuh-LICK-trum / thal-lick-TROY-deez)
False Rue Anemone: Enemion biternatum (eh-NEE-mee-un / by-ter-NAY-tum)
Family: Ranunculaceae (ruh-nung-kyoo-LAY-see-ee), the Buttercup Family
What do you call a plant that has “Meadow Rue” leaves and “Anemone” flowers? You call it a Rue-Anemone! We’re lucky to have not one but two native Rue-Anemones in the St. Louis area. Their names are “Rue-Anemone” and “False Rue-Anemone”.
The word “anemone” (pronounced “uh-NEM-uh-nee”) suggests a “wind flower”. Good luck trying to photograph one when there’s even a slight breeze. The Greek root “anemo” can be found in quite a few botanical terms (anemophile, anemophyte, anemotropism, anemosis, anemochore, anemoplankton). It can also be found in everyday words such as “anemometer” (an instrument that measures wind speed) and my favorite, “anemocracy” (a government controlled by wind or whim).
Neither of our Rue-Anemones are true Anemones from the “Anemone” genus. In fact they’re not even in the same subfamily as the true Anemones. But St. Louis does have 3 true Anemones, including the popular “Tall Thimbleweed” (Anemone virginiana). It’s not included on our Flower-Spotter checklist because it doesn’t bloom until June. Nonetheless, we’ve written about it HERE.
Most people probably don’t even notice a difference between the “Rue-Anemone” and the “False Rue-Anemone”. Although they do look very similar, there are differences. So let’s take the challenge and learn to recognize them as individuals rather than lumping them together. The purpose of this article is to help differentiate these 2 similar-looking plants. This is one of those rare Flower-Spotter selections in which there are 2 plants to find instead of 1. (But 2 points are awarded, so we can’t complain.)
FAMILY: It’s kind of surprising that such similar plants aren’t even in the same genus. But they’re definitely in the same family: the Buttercup Family (Ranunculaceae). The name “Buttercup” sounds so sun-shiny cheerful. But don’t be fooled. Buttercups weren’t born yesterday. This is a primitive family that occupies the lowest rung on the Eudicot ladder. If they had the chance, they’d poison us without batting a corolla. But it’s important that we learn about them because we have no less than 23 of these fascinating species living in St. Louis. (Click HERE to see the entire list.)
We can learn things about flower evolution by studying flowers from plants of ancient lineage. The Buttercup family (which has its roots way back in the Cretacious) is a good case in point. The Ranunculaceae tend to have simple flowers with lots of independent (unfused) floral parts. Their sepals are free, they have a conspicuous ring of free stamens, and most distinguishing of all, they have multiple free ovaries. Sometimes the ovaries in the very center of the flower look like crystals. The flower’s gynoecium is said to be “apocarpous” (carpels are apart from each other). In contrast, more modern flowers usually have only one visible ovary because they’ve largely consolidated their multiple carpels into one “syncarpous” gynoecium.
Thalictrum Photo by Willybilly CC0
RUE ANEMONE (Thalictrum thalictroides)
(Click to view information-rich photos from MissouriPlants.com)
If the botanical name “Thalictrum thalictroides” (meaning “a Thalictrum that resembles a Thalictrum“) seems strange, it’s because the genus name used to be different. Earlier its botanical name was “Anemonella thalictroides“. Replacing “Anemonella” with “Thalictrum” created the comical result.
LEAF: The leaves of this plant are compound and hard to see as a unit, so let’s just deal with the delicate little leaflets instead. Each leaflet looks like a little animal paw. It is palmately veined. At its tip it tends to have 3 shallow, rounded lobes. It’s important to recognize this shape because later it will help us differentiate this plant from its Enemion lookalike.
FLOWER: It’s important to notice two features: the number of petals and the color of the petals. (We’ll call them petals, but actually they are sepals. There are no petals, but these “petaloid sepals” look like petals.)
PETAL NUMBER: This Thalictrum flower usually has 5-10 petals. As we will see, the Enemion flower has only 5. So if we find 6 or more petals, we have good evidence that we’ve found this Thalictrum and not an Enemion. Unfortunately there are plenty of 5-petaled Thalictrums, so we have to be careful.
PETAL COLOR: This Thalictrum has petals that are usually white, but sometimes there is pink in the color. As we will see, Enemion petals are only white. So if we see any pink whatsoever, we have good evidence that we’ve found this Thalictrum and not an Enemion.
FRUIT: Later this month the flower’s dense green cluster of pollinated carpels will develop into ribbed achenes. Each achene has a little beak and will contain a single seed. The achenes will look like green crystals protruding from the center of some ostentatious brooch. After the petals fall away, they’ll look like a bunch of ribbed green bananas. With the onset of summer, the plant will shut down and become dormant.
HABITAT: In the wild, Thalictrum is usually found single on mesic to dry wooded slopes. This is important to note because Enemion prefers more moisture and so would probably not be found in Thalictrum’s favorite habitat (although they are sometimes found together).
For a beautiful introduction to Thalictrum thalictroides, please watch this enjoyable VIDEO (7:31) by Angelyn Whitmeyer. She communicates very effectively with a clear and simple delivery.
Enemion Photo by Outdoorsie CC BY-NC
FALSE RUE ANEMONE (Enemion biternatum)
(Click to view information-rich photos from MissouriPlants.com)
Isn’t “False Rue-Anemone” a horrible name? It tells us nothing. What’s “false” about it? Instead let’s use the genus name “Enemion” (eh-NEE-mee-un). It comes from the Greek word for “Anemone” and even kind of sounds like it. Be sure to put the accent on the 2nd syllable so that it doesn’t sound like “enemy”. (Try repeating “Enemion-Anemone” quickly.) There’s a synonym for “Enemion biternatum” that many people still use: Isopyrum biternatum (iss-o-PY-rum / by-ter-NAY-tum). But for practical reasons, let’s go with whatever binomial Wikipedia chooses to use, which in this case is “Enemion”.
LEAF: The specific epithet “biternatum” is Latin for “twice ternate”. A ternate (or trifoliate) leaf is divided into 3 leaflets, like clover. If each of those clover leaflets were further divided into 3 leaflets, the clover would be “twice ternate” (which clover is not). As we did above, let’s avoid confusion and just deal with the individual leaflet. Enemion’s leaflet, in comparison to Thalictrum’s, has longer lobes with deeper sinuses. Instead of animal paws, they look more like fingers. And if you have good eyesight or a hand lens (which every botanist carries) you’ll notice a tiny glandular prick at the tip of every lobe.
FLOWER: As with Thalictrum, the flower has no nectaries (to the disappointment of the bees). The flower has quite a few stamens with yellow anthers but only 3-6 green ovaries in the center (Thalictrum can have as many as 15).
PETAL NUMBER: Enemion’s flower only has 5 petals. (Again, these aren’t true petals. They’re sepals that look like petals.)
PETAL COLOR: These petaloid sepals are always white (not pinkish).
FRUIT: The fertilized carpels will develop into clusters of beaked follicles, each of which will contain 2 or more reddish-brown seeds. A follicle contains a suture along one side that splits (dehisces) to release its mature seeds. This is different from the Thalictrum’s achene which has no suture and therefore cannot dehisce.
HABITAT: In the wild, Enemion is usually found in colonies on moist bottomlands of deciduous woods with rich loamy soil.
What follows is a debate between the Rue Anemone and the False Rue Anemone. It’s just a silly mnemonic aid, so skip it if you like. Its purpose is to help us remember the differences between these 2 similar spring ephemerals.
THE DEBATE BETWEEN
“TRUE RUE” & “FALSE RUE”
We take you now to a live debate between Thalictrum thalictroides and Enemion biternatum. They will be debating each other for the coveted “Favorite Spring Ephemeral” award. Our debate moderator will be the Spring Beauty herself, Claytonia, the winner of last year’s award. She will ask both of our contestants five questions:
Claytonia: “Welcome, gentlemen, to the St. Louis ‘Favorite Spring Ephemeral’ debate. Before we get started, I’d like to know how you want me to address you. Mr. Thalictrum, what do you want me to call you?”
True Rue: “True Rue” has a nice ring to it. After all, that’s what I am! You can call this other guy “Phony Rue” or “False Rue” or whatever it is that everybody else calls him.
Claytonia: “Mr. Enemion, is that what you’d like to be called? False Rue?”
Mr. Five: “Actually, dear Claytonia, names and titles don’t much interest me. Why don’t you just give me a number. The number ‘Five’ is rather nice.”
Claytonia: “Then Five it is!” The first question goes to you, Mr. Five. How many petals do you have?
Mr. Five: “To be exact, dear Claytonia, neither of our genera have any petals at all. We only have sepals that look like petals. They’re called ‘petaloid sepals’.
True Rue: “Oh just answer her question! You know what she means!”
Mr. Five: “I have 5 petals”
Claytonia: “True Rue, can you match his five petals?”
True Rue: “Match them? I could do that with a leaf tied behind my stem! If I wanted to, I could even double the number to ten! Only five petals? Ha! How can this guy even sleep at night?”
Claytonia: “Here comes my second question, Mr. Five: “What colors are your petals?”
Mr. Five: “They’re white, dear Claytonia. Please notice that W-H-I-T-E has five letters.”
Claytonia: “And you, True Rue? What colors are your petals?”
True Rue: “Oh man, I’m embarrassed for this guy. Only white? What is he, a loaf a Wonder Bread? When I want to, I can put on the most beautiful shades of pink you’ve ever seen! You could say that I’m the proud peacock of the Rue-Anemones!”
Claytonia: “My third question, Mr. Five: “What is your favorite habitat?”
Mr. Five: “I like to live down in the lowlands where it is M-O-I-S-T and where I am fairly close to the W-A-T-E-R. You’ll notice, dear Claytonia, that both of those words have five letters.”
Claytonia: “And you, True Rue? What’s your favorite habitat?”
True Rue: “There’s no way you’d ever find me down there living with the riff-raff. I’m up on the wooded slopes, up where the True Rues belong.”
Claytonia: “My fourth question, Mr. Five: “Do you live alone or with others?”
Mr. Five: “Dear Claytonia, I’m so lucky to share my life with others in a large group. That’s G-R-O-U-P with five letters.”
True Rue: “I ain’t no groupie! No way! I’m a proud one-of-a-kind and I stand alone!”
Claytonia: “My fifth question, Mr. Five: “Describe to me what your leaf-tips look like.”
Mr. Five: “To be exact, dear Claytonia, the proper term would be ‘leaflets’ because…”
True Rue: “Oh just answer her question! You blathering symplocarpus!”
Mr. Five: “I have lobes at the end of my leaflets. That’s L-O-B-E-S, with five letters. And you’ll notice that there’s a tiny point at the tip of each lobe. That’s P-O-I-N-T, again with five letters.”
Claytonia: “And you, True Rue? What do your leaflet-tips look like?”
True Rue: “Well, you’re in for a treat, honey! Look at ‘em! Aren’t they beauts? Look how nice and rounded they are with those cute little indentations. They’re like kitten paws! What did this guy say he has? Lobes? Ha! How freaky is that? I should go out and buy him a pair of gloves.”
Mr. Five: “Oh, that would be kind of you, because I’m a pianist with the St. Louis Jazz Quartet. That’s P-I-A-N-O with five… “
True Rue: “Now I get it! This is a setup! He acts so innocent, so smarmy, but everything he says has five letters in it! He’s tricking us into remembering him! Well try remembering this! E-N-E-M-Y five letters! F-A-L-S-E five letters! Gee, I wonder how many letters ‘idiot’ has?”
Claytonia: “Gentlemen, this is getting out of hand! Treating each other that way! I’m afraid that now I cannot award the prize to either of you!”
True Rue: “Well, Claytonia honey, get used to it. We Buttercups, we’re one toxic family.”
– Michael Laschober
Week #2 (March 27-April 2) Rue Anemone (Thalictrum thalictroides) & False Rue Anemone (Enemion biternatum)
Please protect the plants in our natural areas:
Locations for Thalictrum:
Locations for Enemion: [CAST, CUIV, GLAS, GRAM, LABQ, LITL, MERA, ONON, POWD, ROCK, SHAW, STFR, WASH, YUNG]
Please click on the button below to see a list of all our St. Louis Ranunculaceae plants.