Concept:
Phylogenetic classification systems arrange plants according to their evolutionary relationships and ancestry.
Step 1: Examine various classification systems.
• Linnaeus proposed an artificial system.
• Bentham and Hooker proposed a natural system.
• Bessey and Hutchinson emphasized evolutionary trends.
Step 2: Identify the phylogenetic classifiers.
Both Bessey and Hutchinson developed classification systems based on evolution and phylogeny.
Hence the correct answer is:
\[
\boxed{\text{Bessey and Hutchinson}}
\]