Thallophyta is the most primitive and the largest division of Cryptogams. The plant body is not differentiated into root , stem and leaves and such a plant body is termed as thallus . The thalloid plant body is either unicellular or multicellular.
Fungus (singular) or Fungi (plural) are simple plants called "Thallophyta" that lack chlorophyll (the green coloring that plants use to make food). Because fungi lack chlorophyll, they cannot produce their own food.