Potatoes are not pteridophytes. Pteridophytes are a type of vascular plant that spreads via spore formation rather than creating flowers or seeds. This classification includes Licopodiopsida and Ploypodiopsida, both of which are classes of fern.
While potatoes are usually grown from seed potatoes, which are small tubers with known genetic lineage, the aerial parts of the potato plant do flower and produce fruit. (The fruits are toxic to humans.) Thus, potatoes are angiosperms (flowering plants) rather than pteridophytes.