WASHINGTON, District of Columbia (AFP) - A towering plant that smells like rotting meat and is native to the Indonesian rainforest was in full bloom in the United States (US) capital on Monday, drawing throngs of tourists.

The titan arum, among the world's largest plants, began blooming on Sunday at the US Botanic Garden, and its petals are expected to stay open for just 24 to 48 hours.

Curator of plants Bill McLaughlin said he first noticed the smell at around 6pm on Sunday.

"I felt a little queasy for awhile and I wasn't able to eat really until about 11pm last night, after a few hours of air," he told AFP.

At first, the plant gave off heat he could sense with his hand and the smell shot straight up in the air, he said.

After that, an odour bearing heavy notes of roadkill "sort of curls back down, taps you on the shoulder and you look around for something dead," he said.

The flower is 2.4m tall and smells of decomposing flesh in order to attract pollinators like carrion beetles and dung beetles.

Its blooming is unpredictable, and may happen every few years or every few decades.

Once the petals open fully, the bloom only last 24 to 48 hours before collapsing.

"The plant requires very special conditions, including warm day and night temperatures and high humidity, making Botanic Gardens well suited to support this strange plant outside of its natural range," the garden said in a statement.

The plant was first discovered in 1878 and the last time one bloomed at the US Botanic Garden was in 2007.

"We have had more than 98,000 people come visit from July 11 through July 21... unbelievable number of people!" said garden spokesman Laura Condeluci.

Visitors waited in line in soaring summer heat for a chance to see and smell the flower, but some were disappointed that the worst of the stench had already passed.

"Not nearly as smelly as I had hoped," tweeted one visitor named Robin.