Which one of the following is wrongly matched?
Root pressure-Guttation
Puccinia-Smut
Root-Exarch protoxylem
Cassia-Imbricate aestivation
Puccinia is the rust fungus and Smut is the Ustilago. Both rust and smut-causing fungi are from the class Basidiomycetes.
Therefore option 2 is the correct option.