Well, you could have talked about potential uses such as concrete- bordered hellstrips or wild hillsides. In the link you posted, the author did just that; whilst battling it in her cultivated beds, she found it useful on a rocky slope.

So, there’s a plant for every situation. I’ve actually been interested in it for a weedy slope that’s away from my more intentional “ gardens”, but would want to know more about its ability to spread by seeds to areas I wouldn’t want it. Plus so far there may be better native alternatives.

Maybe it could've been a teaching lesson, but she sent me pictures of other things I'd not put into my garden either. Sort of reminded me of the gardener with the username kudzu who hung out here forever ago. Always wanted to sing the benefits of something the South is still battling with goats. I think the garden club participant just wants it easy and to "smother weeds". That's my least favorite phrase to hear. There's no such plant. Well, it will smother weeds and everything else in its path.

marmie, read closer...

"...But it saw a golden opportunity (rich soil, full sun, lots of room) and has popped up amid young plants that are not yet established" I'm pretty sure she knew battle was about to begin. It will choke out everything in its path. Those roots grow a foot down into the soil. You're not getting them out. I'm happy to grow O. macrocarpa all day long. But pink ladies? Nope. It's right up there with Myosotis sylvatica. Never.

Good to know!

Is there a native variety that is more desirable? Here it is oenothera biennis. Long story short, I share an allotment plot with a neighbour who for the past two years has gone AWOL. She kept indicating she may be returning, so I decided it was just easier for my sanity to divide the plot in half and maintain just my side. So of course her side became all overrun, and I noticed colonies of the evening primrose had established there.

In fairness to us plant sale people, sometimes it’s not only what takes over our gardens that we pot, but is easy to divide, pots up easily, rebounds nicely in the pot for an easy sale. I’m no expert, but I’ve been learning a bit about propagation through trial and error. I’ve learned in my established garden that some plants form such dense, thick, root masses - that you can easily take chunks of it out, chop it into small bits, and each of those bits produces a nice size plant very quickly. Most of these plants don’t fall in the invasive category - just in the easy to divide category. I have this one single helianthus; I dug it up and the root mass was huge, like a rhubarb. So I literally chopped it in half, threw the one half back in the ground, and the other half divided into like small bits. Ended up potting up 18 one gallon containers! Thought I had gone overboard by doing it too early in the season (early March!) and had likely messed up, but all those pots are showing great growth.

somewhat OT,

but the O speciosa seems to catch moths, because the flower spure does not go together well with some of the "moth notzzels" (what is the proper term for their drinking organ, pls?)

for some reason several moth species get stuck in the flower while reaching for the nectar and die. I read about it on a German garden forum, but there are other articles on this phenomenon as well

just so you can avoid it if you are into wildlife gardening (or just considerate). I personally toyed with the idea of getting some plants, liked their resilience, but switched to something different after learning of the "moth catching"

Oenotherea speciosa killing some moths

LaLennoxa, I'm happy to grow O macrocarpa all day long. It has the most gloriously gigantic yellow blooms. It even grows from cuttings easily. I've never had it reseed, but I'd be thrilled if it did.

https://www.applewoodseed.com/product/evening-primrose-missouri/

Linaria, I hadn't heard that; it is sad.

Yes to O. macrocarpa! I adore this plant too Rob.