The Titan Arum, which gives off a stench like rotting corpses, began to open this morning for the first time in its 13-year lifespan.
The plant has already revealed the spathe of a flower but is likely to bloom fully within the next fortnight.
Experts have been keeping a close eye on the plant, which only produces its distinctive bloom every seven to ten years.
Before today staff still do not know whether the bud would produce a flower or a leaf.