 The common name "glasswort" came into use in the 16th century to describe plants growing in England whose ashes could be used for making soda-based (as opposed to potash-based) glass.The ashes of glasswort plants, and also of their Mediterranean counterpart saltwort plants, yield soda ash, which is an important ingredient for glassmaking and soapmaking.Soda ash is an alkali whose active ingredient is now known to be sodium carbonate.