No, the Marsh Mallow, is a plant we call Hibiscus syriacus, and that is a shrub. It is a very strong growing plant that flowers here in mid summer. It is also a plant which seeds freely, and can become a nuisance for that reason.
Sometimes nurseries/garden centres can get their labels mixed up, and when it comes to small new plants it can be easy to mistake one mallow plant for another.
I wondered if yours may be one like that if it has seemingly disappeared.
If you bought your plants online, and cannot guarantee that you were sold the correct plant, and maybe have been sent a different variety if may account for the fact that it isn't actually there any more.
There isn't any kind of miracle that will help this/these to reappear, we don't have any magic wands, they are just for fairy tales.
