Ronna Scoratow, right, examines her 42-year-old philodendron with horticulturalist Margie Radebaugh. James R. Hagerty/The Wall Street Journal
PITTSBURGH— Ronna Scoratow has had a cat, poodles and parakeets, but no companion has proved more durable than her 42-year-old philodendron.
"This is my girl!" she announced as visitors arrived one recent morning to see the 7-foot-tall potted plant, known as a lacy tree philodendron, that dominates her living room. There is only one shadow in this love story: "This plant will definitely outlive me," said Ms. Scoratow, a landlady who is 63 years old and in good health. "After I pass, I don't want her to go unloved."
Ms. Scoratow has no children. Her siblings don't share her enthusiasm for indoor greenery. So last year she put a provision in her will granting $5,000 for a friend to use in caring for the plant. "It was interesting," her lawyer, James Wood, said when asked about that provision. "I've done provisions for pets but never a plant."

Plants That Might Outlive You

Philodendron Getty Images
Many people have pondered the burdens of caring for an aging human population. Fewer have noted the risks that geriatric house plants could be left without support.
"I don't know what is the life span of a philodendron," Ms. Scoratow said. "I imagine it's infinity if you take care of it."
Some plants live for centuries. A giant cycad has thrived in London's Kew Gardens for nearly 240 years. But eternal life? "I would say no," said Margie Radebaugh, director of horticulture at Pittsburgh's Phipps Conservatory and Botanical Gardens, half a mile from Ms. Scoratow's condo.
The plant was less than a foot tall when a friend gave it to Ms. Scoratow in 1972. It kept growing. One night in the 1990s, its weight finally shattered the glass table on which the plant sat. She moved it to a pot on the floor. From there it spread and, for a time, rooted into the floor planks.
Now the philodendron's dozens of deep green fronds coil and stretch in all directions, blocking a picture window that could otherwise offer a view of the University of Pittsburgh.
When Ms. Scoratow moved from a house to her condo a year ago, she had to pay movers $370 to haul the plant.
Philodendron leaf
Philodendrons tend to be hardy. Scott Aker, head of horticulture at the National Arboretum in Washington, D.C., said they originally came from jungle floors and don't need much light. Other plants that tend to do well indoors include snake plants and aspidistras, he said.
Even aspidistras, known for thriving in dimly lit bars, aren't fool proof. "Human error can be deadly to plants," Mr. Aker said. That can include too much water or too little.
Bonsai trees are famous for lasting centuries. The National Arboretum has one more than 400 years old. The arboretum keeps its bonsai in a pavilion most of the year. The bonsai generally need seasonal temperature variations and most couldn't survive at household temperatures.
Ms. Scoratow is surprised at how easily other people abandon their flora. She often rescues plants that have been left at curbside. She pointed to another plant, more than 6 feet tall, of a type she hasn't been able to identify: "I don't know how I got it in my Honda, but I did."
Aside from the philodendron, "almost every plant here is a rescue," she said. "This is like the plant hospital."
She hasn't made long-term provisions for her other plants. "I don't have the same love with them. I don't know how to explain it. I don't want to be cold or anything." The others are smaller and easier to move, so she hopes someone will take them when the time comes. Her philodendron is special, Ms. Scoratow says, because "I've had that one the longest."
Other indoor gardeners say house plants can outlive their welcome.
Ella Johnsen, 84, who lives on a ranch near Miles City, Mont., inherited an asparagus fern in 1949 from relatives. It had bounced around in her husband's family and was believed to date to the 1920s or 1930s. Ms. Johnsen called it "the family fern."
About a decade ago, Ms. Johnsen said, "I was tired of it, and I was tired of cleaning up after it. It seemed to shed a lot of leaves." After her daughter refused to take the plant, Ms. Johnsen sold it to a friend for $15. The friend, Norma Tom, said it continues to thrive even though she doesn't bother to spray it with mist.
Even the most ardent house plant lovers have their limits. Plants "bring meaning to people's lives," said Barbara Pleasant of Floyd, Va., author of "The Complete Houseplant Survival Manual." She believes more people should own them. Yet Ms. Pleasant doesn't see every house plant as a lifelong commitment.
"I've got a begonia I'd like to get rid of," she said. The pink blossoms "don't look all that showy and they scatter all over the floor."
Ms. Scoratow isn't alone, however, in thinking about what her death might mean for a cherished plant. Christopher and Karen Upton of Adelphi, Md., both horticulturists, have a ponytail palm in a corner of their living room. The Uptons believe the palm is about 50 years old. They call it Gordon, after a friend who swapped it to Ms. Upton 37 years ago for a Porsche steering wheel.
"It can take pretty much any abuse—cold, hot," Ms. Upton said. "It's a really well-behaved plant," with minimal shedding. Eventually, though, the Uptons may grow too frail to care for the palm. Mr. Upton, 62, said their exit strategy might be to take Gordon down to Florida and "set him free" outdoors.
Tiffany Wamsley, 46, a homemaker in Opp, Ala., said her snake plant is more than 70 years old. She also has a dragon tree that she believes is at least half a century old. Both were gifts from her maternal grandmother.
When Ms. Wamsley moved from Columbus, Ohio, to Opp seven years ago, she loaded a U-Haul trailer with furniture and clothing. Then she wedged in 20 plants. All survived the 800-mile trip.
"It would be a concern of mine if I get an illness: Who's going to take care of my plants?" Ms. Wamsley said. When told of Ms. Scoratow's $5,000 legacy to ensure care for her philodendron, Ms. Wamsley said: "That sounds perfectly reasonable to me, and actually kind of a low figure."
Write to James R. Hagerty at bob.hagerty@wsj.com