You purchase from reputable places, and you normally get properly named ones. If they match the plant on the web page for the reputable grower, you can expect they're proper. Growers make mistakes too, but normally if it's a mistake it won't match the picture on the site where you purchased it, and then often the grower can identify it, as they grow them by alphabet, or numbers, and it was probably a plant grown right next to the right one.
And, that, Ms. Chelle, was an excellent question!
