Rue anemone or false rue anemone?
The previous two pictures look really similar. (There’s even a log in each!) They’re white flowers, approximately the same size, with very similar leaves. But they’re different: all of the flowers in the first photo have five petals, but only some of the flowers in the second photo have five petals, and most have more than five.
I can always remember that there is a distinction in the petal numbers, but I haven’t been able to remember which is which without looking it up. Thank goodness for minnesotawildflowers.info.
Color might help: if it’s pink, it’s rue anemone. But with such similar common names, what are the chances I’ll remember that? Slim.
In addition, both can be white, so it’s not safe to rely on color. So it’s back to counting the petals. False rue anemone always has five petals; true rue anemone has between five and ten.
However, that rule has never stuck with me. I have to keep learning it and re-learning it. Even in my own garden — where I have one of these flowers but not the other…
… the only way I know for sure is to look at the tag.
This year, I posted this problem on Instagram and asked if anyone has a mnemonic to help. Within a couple hours, a new Instagram friend, Jenny Stratton, responded with this spur-of-the-moment suggestion:
Five is false, ten is true?
Let’s give it a try:

One problem is that five petals could mean either flower. But a patch of true rue anemone, as far as I have seen, never has all five-petal flowers. In fact, I usually don’t see any with five; it’s usually six or eight. As long as I am not in a hurry and look at the entire patch of flowers instead of just one individual, I’ll get it.
This is a great lesson, and I’m so glad that I could contribute to it! I had never tried memorizing the difference before, since (to my knowledge) the only time I’d seen Thalictrum thalictroides (Rue anemone) was pre-identified on an herbarium sheet. Really enjoying the sweet reminder of Midwestern flora on your blog :) :)