In House of Cards‘ Chapter 64, Claire Underwood murders Tom Yates by placing something in his drink. So what is it that Claire poisoned Tom with, exactly?
Well, this was actually set up at the very beginning of the episode. About eight minutes into Chapter 64, Claire speaks with Jane Davis, and Claire notes that she has a migraine. So to help her, Jane gives Claire some Gelsemium, which Jane says she gets all the time from China.
When Jane gives Claire the bottle of Gelsemium, she specifically warns Claire not to use more than one dose, which turns out to be a pretty blatant piece of foreshadowing.
“You have to be careful of the dosing, though,” Jane says. “Just two drops.”
Later, after Claire poisons Tom, we see her pull out this same bottle of Gelsemium from earlier. The bottle appears to be quite light, and so presumably Claire just poured the entire bottle into Tom Yates’ drink.
So can Gelsemium actually result in death, or is that an exaggeration for the show? Believe it or not, people really have died after someone put Gelsemium into their food or drink. In 2011, for instance, a Chinese billionaire died after consuming meat which had Gelsemium in it. Another man was subsequently arrested on suspicion of poisoning the food, according to BBC.
Gelsemium is also used to poison a character and ensure a quick and painless death in the show Outlander.
In small doses, Gelsemium can be used to treat illnesses, though, including neuralgias.
In cases of Gelsemium death, the victim usually suffers cardiac arrest, which seems to be what happened to Tom Yates on House of Cards, although in real life it almost certainly would not happen that quickly, and Yates would show symptoms for longer than he did before his death.