Marsh mallow and Marshmallow

Marsh mallow noun - European perennial plant naturalized in United States having triangular ovate leaves and lilac-pink flowers.

Marshmallow and marsh mallow are semantically related. In some cases you can use "Marshmallow" instead a noun phrase "Marsh mallow".

Marshmallow noun - Spongy confection made of gelatin and sugar and corn syrup and dusted with powdered sugar.

Marsh mallow and marshmallow are semantically related. Sometimes you can replace phrase "Marsh mallow" with "Marshmallow", this terms are similar.