Althea officinalis - Mallards, Mauls, Schloss Teai, Cheeses, Mortification Koot, mallow, white mallow, common marsh-mallow, marshmallow, mortification root, sweet weed, wymote. Marshmallow Root leaves should be picked just as the plant begins to flower. The leaves are used as a potherb. May be added raw to salads or to soups to thicken them. They are mucilaginous and adding too much to the soup will make it slimy. The root has the highest mucilage content in the winter and should be harvested as late as possible in the season, on a dry day, from plants at least two years old. The sap was mixed with egg whites and sugar and whipped into a foamy meringue, baked and cut into squares and used for sore throats. The root of this plant was once used to make pate de guimauve, a sweet confection similar to today's marshmallows. Prior to that, a similar treat was made in Egypt using marsh mallow sap and honey.