The Ginger Killer

"Well, my dear Watson, I believe the solution is fairly obvious. Would you agree?"
"Actually, yes, Mr Holmes," said Watson. "It was clearly the gardener. Nobody else was in the house and he left behind a fistful of short ginger hair. And this," he pointed to a vase of flowers on the table, "was the murder weapon."
"Oh, my dear Watson," Holmes interrupted. "It was the cat."
"The cat?" Watson repeated.
"Your diagnosis was correct," Holmes continued. "Anaphylactic shock. But not from pollen."
"How so, Mr Holmes?" Watson asked.
"Let me explain," Holmes smiled while leading Watson towards the garden.