Among the Green Algae the differentiation of cells is comparatively slight.
The thallus in all cases consists of a branched filament of cells placed end to end, as in many of the Green Algae.
Similar modes of growth occur among the Siphoneous Green Algae and also among the Red Seaweeds.
For the carrying on of their functions they all need to be supplied with carbohydrates or other carbon compounds which they obtain ordinarily from humus and plant residues in the soil, or possibly in some instances from carbohydrates manufactured by minute green algae with which they live in close union.
It is true that certain Bryophyta (Marchantiaceae, Anthoceroteae) possess a thalloid structure similar to that of Thallophyta, and are at the same time possessed of the colouring matter of the Green Algae.
