The Mallow plant(marshmallow comes from this plant) looks like hibiscus but is larger. The Rose of Sharon's flowers look like the Woody Hibiscus. Hibiscus is tropical and adds flair to your surroundings.
The mallow has the same appearance as a hibiscus. It is usually slightly larger than the hibiscus, though. Also, the flower cups are more shallow since they are a bit flatter. The flowers are deep pink or purple with dark lines. They grow easily in my experience; their also pretty resiliant in almost any soil.