clicking edit or the gaps between paragraphs it can be seen there are two answers.
My first suggestion would be
A tree? In particular a tree in autumn
But the better answer suggested by @Sensoray is
The Stinking Corpse Lily
Lifeless, but alive,
An aura of death surrounding.
The flower is a 'corpse' but alive as it is a flower. It stinks or rotting corpses.
Flies and maggots prosper,
The smell of rotting meat attracts many flies
Limbs of crimson,
The flower is the biggest flower in the world and has giant red leaves
In the middle of the red flower is the stigma. Red also symbolises danger.
And as for the second answer:
It is poison ivy.
The hidden riddle is
The words lie
Leaves of three
Let them be
Who am I?
Give me both answers!
The answer is
Posion ivy, which has three leaves and should be avoided