When you’re the world’s largest flower, you get to be a diva. You demand to be fed and watered continually, you control the thermostat, and you go onstage when you’re good and ready.

Even when you get your way, you create a stink. The size, the odor, the capriciousness, these are all the elements of fascination with a grotesquely beautiful Sumatran jungle plant so gluttonous it even has a string of names: the titan arum, the corpse flower or the Amorphophallus titanum.

Elliott Norman, horticulturist at the U.S. Botanic Garden, waters the titan arum he has raised since 2010. It is on display in the conservatory’s Garden Court awaiting its expected unfurling this weekend or early next week. (Adrian Higgins/The Washington Post)

It grows to six feet tall or more, is surrounded by a sinister-looking cape and, for a few hours, pulsates with a stench that could make a pirate retch. Each individual takes as long as seven years between flowering, and because no one can tell when, exactly, it will bloom, this week’s appearance of four specimens in East Coast botanical gardens seems unprecedented and sure to increase the hype that accompanies its appearance.

The titan arum at the New York Botanical Garden opened Thursday afternoon, drawing visitors to the Palm Dome at the center of the Haupt Conservatory. The botanical garden is in the Bronx, and this is its first titan arum flowering since 1939. Before the event, grower Marc Hachadourian said he felt “like an expectant father.”

United States Botanic Garden

Visitors are arriving, too, at the U.S. Botanic Garden’s conservatory at 100 Maryland Ave. SW for the fifth public display of a titan arum in the District, two of them by the Smithsonian. Moved from its home greenhouse in Southeast Washington on July 22, the titan arum is expected to unfurl sometime between Saturday and Tuesday.

By Friday, its growth rate had slowed markedly, suggesting it was preparing to open, spokesman Devin Dotson said.

The botanic garden has extended its hours to 8 p.m. this week and will remain open until 11 p.m. on the day it opens and the day after, he said. This is to allow visitors to catch a whiff of the beast, which waits until dark to emit its stench as a way of luring pollinating carrion beetles.

Stinking up the place takes a lot of energy — the plant actually heats up to more than 100 degrees — so the odor is fleeting and comes in waves or, more likely, tsunamis. Because of the timing, most people who view the plant won’t smell much, but the sight alone is spectacle enough.

The other two titan arums are in one place, the Marie Selby Botanical Gardens in Sarasota, Fla. Its first, named Seymour, bloomed last weekend and by Friday was all but gone save a portion of its central stalk. The second, Audrey, is expected to open this weekend or early next week. The names come from the 1980s musical and film about a maneating plant, “Little Shop of Horrors.”

In July 2013, the last titan arum to bloom at the U.S. Botanic Garden, nicknamed George, drew thousands of visitors. Similar crowds are possible this weekend for the next bloom. (Matt McClain/The Washington Post)

Horticulturists at the three botanical institutions hope to share pollen for breeding purposes, because the arum does not self­pollinate. Washington and New York have live webcams (USBG webcam is here, NYBG webcam is here). Selby Gardens has Facebook updates.

As with the Washington specimen, known internally as Charlotte to distinguish it from George, which bloomed three years ago, Audrey is currently in a coiled phase but is expected to bloom around the same time as the D.C. arum. The central spire, known as a spadix, is wrapped partially in a skirt called a spathe. This resembles a furled umbrella that gets fatter and more ruffled by the hour before opening. Botanically, the titan arum is the largest unbranched flower structure in the plant kingdom.

Its flowering has become a hugely popular if not common phenomenon in botanical gardens around the world, not least because this plant draws thousands of ticket-paying visitors. Uniquely, admission to the U.S. Botanic Garden is free, and its grower, Elliott Norman, and plant curator, Bill McLaughlin, are simply thrilled to get visitors during the oppressive heat and humidity of high summer in Washington. Visitors are itching to take a selfie for their social media sites, they say. “It’s a bucket list for people to experience,” McLaughlin said.

“A large, smelly bucket,” added Norman. He has been growing this week’s titan arum since 2010, when it was a pea-size offset of its mother bulb, or corm. Its bulb is now about 50 pounds, small for a blooming titan, but nothing about this plant has been predictable. Norman usually can figure out three months in advance whether new growth will turn into a flower, rather than the more common and persistent leafy stalk. But Charlotte only gave him a couple of weeks’ notice. Its mother plant has yet to bloom.

The twin titans at Marie Selby Botanical Gardens, Audrey and Seymour. When Audrey, left, opens, the horticultural team will use Seymour’s pollen for a pollination attempt. Seymour has since collapsed. (Marie Selby Botanical Gardens)

The plant is also growing at a rate and size beyond expectations, given the smallish girth of its bulb. As of Friday, it was 6 feet 9 inches inches high; Audrey was 5 feet 8 inches, and the New York specimen topped out at 6 feet 4.

“It took us by surprise, and its performance has been amazing; it’s far larger than expected,” McLaughlin said.

When George bloomed in 2013, the horticulturists set up a stepladder after-hours to get pictures and to experience the most potent period of odor. Norman, being an incurable romantic, took his wife along. “After the third wave we decided to leave. We thought the next one would cause us to fall off the ladder,” he said.