City spokeswoman Gayleen Froese says staff at the Muttart Conservatory are comparing the giant plant to a pregnant woman whose water has broken.
She says there's a small opening at the top of the plant and a faint odour like vinegar.
Staff are anxiously expecting the flower to pop open in the next few days.
The tropical plant, found in the wild in Indonesia, produces a large purple-reddish bloom and smells like rotting meat.
The bizarre stench lasts only for one day, so staff plan to alert curious visitors on Facebook and Twitter.
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