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Wistaria Festival: How did Sierra Madre's record-setting wisteria get so big?

This Sunday the town of Sierra Madre holds its 97th annual Wistaria Festival, during which the public is invited to check out the massive woody vine that’s grown so big it’s in the Guinness Book of World Records as the largest blooming plant.

So how did this wisteria get to be the biggest in the world? (And why does Sierra Madre spell it with an "a" and not an "e"?)

The vine started in 1894 and now covers an acre of land in the foothills of the San Gabriel Mountains.

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Wisteria is a famously hardy plant. It originally came from Asia where it's prized for its beautiful hanging flowers and ability to live for decades.

As for Sierra Madre's famed plant, "It has a lot going for it for why it’s so old and big," said Gretchen North, a biology professor at Occidental College.

North says the San Gabriel foothills are great for wisteria. The area is not too windy. It’s warm with very few hard frosts. And since the plant is non-native, there aren’t as many natural pests and diseases to harm it.

Wisteria is a legume, and North says that means it has a very unique relationship with naturally occurring bacteria in soil called rhizobia.

These rhizobia enter the plant's roots and interact with them to create an enzyme that pulls nitrogen from the air into the soil.

"So it never suffers for lack of nutrients," North explained. "Basically it can grow in very poor soil and manufacture its own fertilizer."

Frank McDonough, the Botanical Information Consultant with the Los Angeles Arboretum, thinks the Sierra Madre wisteria might also be tapping into an underground water source.

"For a plant to get that big, especially a vine, it's going to need a lot of water," he said.

Luckily for the wisteria, McDonough says the area around Sierra Madre is unique in that it has pockets of water not too far underground. Some are fairly isolated, and he thinks the plant may be tapping into one of those pools.

He adds it doesn't hurt that the plant has had conscientious owners who occasionally weeded and watered it over the years.

"So our symbiosis with that plant is another factor in that plant being so long lived and so big," he said.

Wisteria history

It started as a young vine bought and planted by Alice Brugman in 1894, says Phyllis Chapman, Sierra Madre's unofficial historian.

"She is said to remark: 'Wisteria is a fast grower,' which is perhaps the understatement of the century.”

By some estimates wisteria can grow 24 inches in 24 hours.

The Sierra Madre plant quickly spread and eventually destroyed the original two-story home on the lot after it was abandoned.

"It grew into the walls. Caused the roof to collapse and so forth. You know wisteria are very vigorous growers.”

By the way, the plant is commonly spelled "wisteria," but the town of Sierra Madre prefers to spell it "wistaria," a name referring to the American physician Dr. Caspar Wistar. The spelling is a matter of some debate among plant enthusiasts.

These days, Sierra Madre's plant grows on trellises that span two backyards. One of those homes is owned by Nell Solt.

She waters it in the summer and occasionally trims dead branches, but she says for the most part, it takes care of itself.

She is quick to point out she doesn't consider herself a plant expert.

"I could kill plastic flowers," she said with a laugh.

Lucky for her, this wisteria seems to be doing just fine.

Have you seen Sierra Madre's wisteria? Share you photos with us on Facebook, Instagram or Twitter ("@" mention "@KPCC"). For more information on the Wistaria Festival, which will be held Sunday, March 16, and to buy shuttle tickets to see the plant, click here.