I bought the plant in Spring '24 at Home Depot described on tag to grow ~15" tall and thought it would be a nice tall accent to the begonias planted around sides of pot. Well, it took over the pot and shaded out my begonias. I've misplaced the tag. I must've forgotten to slip into side of pot.
It seems to be unfazed by light frost in southern PA. When I cut some stems for a vase of other flowers, it grew roots. I don't recall any blooms but wonder if it is loropetalum and I should plant it in the ground.
Photos attached. You can see one pitiful begonia peeking at base of pot. Thanks!

Maybe this Alternanthera brasiliana

Are the stems woody or fleshy like Begonias? Has it flowered?
If woody, I'd say yes Loropetalum. With flowers, Loropetalum.
If fleshy, I'd go with Alternanthera.

Mystery plant has opposite leaves.
Loropetalum leaves are alternate...which rules it out.

Alternanthera has opposite leaves.

Yes I also says Althernanthera, not Loropetalum
In the case of Loropetalum vs Alternathera it is very easy to distinguish both using Phyllotaxis (the arrangement of leaves) ,
Alternanthera has opposite leaves (in pairs one opposite to the other), Loropetalum has Alternate leaves (single leaves alternating in the other side of the stem)
Also the set of leaves in Alternathera will be "Decussate" meaning the set of leaves will be criss-cross with the above and below set, while in Loropetalum it is "Distichous" meaning they are in one plane

So your plant leaves are "Opposite and Deccusate" consistent to Alternanthera
Loropetalum leaves are "Alternate and Distichous"



crop illustration from https://doi.org/10.1007/s12374...


A trivia; although the Genus name is Alternanthera but the leaves arrangement is not "alternate". The genus name related to the flower not the leaves on this one. alternans, (alternating) and anthera, (male flowers) which refers to the alternating arrangement of stamens and pseudostaminodes in the flower of this genus.

Thank you all

I got one this spring @ L's that has also grown a LOT. IDK how many purple varieties were in commerce this year but mine was labeled as this:
Alternanthera Plum Dandy™

Ditto, an Alternanthera. Someone gifted me two types. ( Purple prince, red threads..?) They have not rooted easily for me in water. But he must have rooted cuttings.

Update, some cuttings in water have eventually rooted. And I put more into a pot with loose plastic tent for humidity- I expect better luck this time.

I've had luck with sticking cuttings of this in water & directly into soil. Is anybody else's plant blooming? Seeing blooms on mine. Will get a pic as soon as I can.

Huh, mine never bloomed this summer, that I noticed, though it looked lush.

I think it's a short day bloomer. It's usually an inside plants when I see blooms, or very early spring. But it might prefer summer farther north, IDK.