Schematic evolutionary tree of Viridiplantae based on the Tree of Life Web Project. Different colours indicate the presence of any modern species in the clade with at least one transcript assembly belonging to the cystatin family, the papain-like C1A, and/or the legumain-like C13 cysteine proteinase families. Green, presence of cystatin, C1A and C13 proteins. Grey, presence of C1A and C13 proteins. Yellow, presence of C1A proteins. Pink, presence of cystatin and C1A proteins. Absence of colour indicates clades without representative species in the TIGR plant transcript assemblies database.