Earlier classification systems included bacteria, blue-green algae, fungi, mosses, ferns, gymnosperms and the angiosperms under ‘Plant’ kingdom. The character that unified this whole kingdom was that all these organisms had a cell wall in their cells. This placed groups together which widely differed in other characteristics. It brought together the prokaryotic bacteria and the blue-green algae (cyanobacteria) with other groups which were eukaryotic. It also grouped together the unicellular organisms and the multicellular ones, for example, Chlamydomonas and Spirogyra were placed together under algae.