The plant is brought to him anonymously as a gift on Christmas Day, 1995. His caretaker assumes it’s a harmless Flitterbloom and encourages him to take care of it. When he touches it, it strangles him.
The plant had been brought by Walden Macnair in order to kill Bode, who was recovering from the spell damage which prevented communication. The Death Eaters knew that, should he recover, he would tell the Ministry that it was Lucius Malfoy who had placed him under the Imperious Curse to force him to take the Prophecy out of the Department of Mysteries. They had to find a way to kill him before he was able to communicate.