What the multiplication sign means
Mentha ×piperita, Citrus ×limon, Citrus ×aurantium. The sign marks a hybrid — a cross between two species — rather than a species in its own right. It is not decoration and it is routinely dropped in trade writing, including by this catalogue until it was checked.
Peppermint
A cross of watermint and spearmint. It is sterile, so every peppermint plant in the world descends by cutting from a small number of original clones. That is why it cannot be grown from seed and why peppermint is unusually uniform compared with the other mints.
The citrus tangle
The lemon is a hybrid. The bitter orange is a hybrid of pomelo and mandarin. The sweet orange is a hybrid too. A very large part of the citrus shelf is a small number of ancestral species crossed and re-crossed, which is why citrus taxonomy is difficult and why 'native range' often has no answer.
Spearmint may be one as well
The taxonomic record notes that spearmint probably arose by allopolyploidy — a hybridisation event that doubled the chromosome count. So the plant universally described as one of peppermint’s two parents is likely a hybrid in its own right.
What it means practically
Buy a hybrid as a named plant rather than as seed. Do not expect a wild origin story. And read any confident statement about where a hybrid 'comes from' as a claim about where it arose in cultivation, which is a different and usually less certain thing.