Nearly extinct in the wild, the tropical plant has leaves reaching nearly 20 feet in height and a flower which smells like rotting flesh.
The specimen currently blooming is nicknamed Suma the Titan, and is a sibling to Terra the Titan, which bloomed last year.
"These plants are now ten years old," said Conservatory communication manager Maryam Nabi, noting that this is Suma's first bloom. "Terra, who bloomed last year, is now in the leaf stage of their life cycle and can be observed in our Potted Plants Gallery."
Originally propagated by UC Berkeley Botanical Garden from parent plants Trudy and Titania, Suma and Terra were donated to the Conservatory in 2014--in Terra's case, from a private collector named Sidney Price who kept the plant for years in his Mission apartment bathroom.
Peak bloom for the plant will last only about three days, according to Conservatory botanists. To accommodate visitors, the Conservatory is offering extended hours, 10 a.m - 10 p.m. through Wednesday.
The Conservatory is also live streaming Suma's progress on YouTube.
It's unclear whether the facility has increased security for its fragrant star attraction: in January 2017, an unidentified man became a viral video sensation when he crossed a barrier to fondle Terra the Titan while a companion took photos.