Muggles' Guide to Harry Potter/Magic/Devil's Snare

Overview
Devil's Snare is an extremely dangerous plant that will, as suggested by its name, ensnare wizards when disturbed. It strangles those who approach it by wrapping them in its (usually dark, and in a developed plant thick) tendrils. Possibly this is a magical variant of the Muggle Venus Flytrap or pitcher plant, that capture insects for food. We suspect that in the wild it can also capture and consume larger animals such as cows. If this is the case, "playing dead" is not a defence; lying still may prevent it from strangling you, but will trigger the plant's attempts to start growing roots into you, and the strangling will resume as soon as you try to get away.

Extended Description
A plant of the dark and dank, it reacts to heat and light by retreating. When Harry, Ron, and Hermione are trapped in it, in Harry Potter and the Philosopher's Stone, Hermione remembers this sensitivity, and, when prompted by Ron, manages to create fire that makes the plant retreat.

Devil's Snare appears again in Harry Potter and the Order of the Phoenix. Here, Harry, Hermione, Ron, and Ginny see a small specimen delivered as a gift to one Broderick Bode, a long-term spell-damage patient at St. Mungo's Hospital. Hermione later reads in the Daily Prophet that Bode, encouraged to tend this plant as part of his healing, had been strangled by it.

Analysis
Given their previous experience of the plant, one must wonder why Harry, Ron, and Hermione did not recognize it when they saw it delivered to Bode. Harry does admit to being made uneasy by the potted plant's swaying tendrils. It is possible that they had simply been distracted by their encounter with Gilderoy Lockhart.