Correction: An earlier version of this story incorrectly referred to a tree in the National Arboretum’s bonsai collection as an Umaki pine. It is a white pine. The story has been updated.

Goshin is a planting of 11 juniper trees started by American bonsai master John Naka in 1948. It is on display at the National Arboretum's National Bonsai & Penjing Museum. (Bettina Lanyi/For The Washington Post)

There are gardeners who plant flowers, grow vegetables and cultivate landscapes.

Then, there are gardeners who curate bonsai — ornamental trees cultivated in pots and trained to grow to a miniature size.

“Bonsai are much like pets,” said Jack Sustic, curator of the National Bonsai & Penjing Museum in the District. Penjing is the Chinese word for bonsai, which Sustic explains is pronounced “bones-eye.” “You have to water them every day, unless it rains, so if you go on vacation you have to find someone to take care of them — you can’t just leave them. My oldest tree I’ve had since 1990. I’ve been cultivating it that long. It’s more than just a tree to me. It’s almost part of me, in a way.”

The National Arboretum started its Bonsai & Penjing Exhibit in 1976 with 53 bonsai. The trees were a gift from Japan for the U.S. Bicentennial, commemorating the relationship between the two countries: one tree for each state, and three more from the imperial palace. The arboretum’s collection has grown to about 300 trees, displayed throughout the museum’s Japanese, Chinese and North American collections.

Each bonsai has its own personality; some are even known by a single name, like a rock star. Mamasan, the oldest tree in the collection, is a white pine nearly 400 years old. Part of the original 1976 Japanese donation, Mamasan was two miles from Hiroshima when the city was bombed by the United States during World War II.

The North American collection also houses Goshin, considered the most famous bonsai in the world, which was created by the late John Naka, known as the Father of American bonsai.

“They are magnificent; it would be easy to be intimidated,” Sustic said. “Bonsai is also a verb, I feel. When I’m out here watering the tree, it’s an action, it’s not just a noun.”

The curator said one of the greatest misconceptions about bonsai is that they are a special breed of tiny tree.

“People think they’re genetically dwarfed; that a special kind of tree makes a bonsai,” he said. “That’s not the case. It can be anything that gets a woody trunk. Any tree can be a bonsai. It’s all in the trimming techniques and the timing. If you wanted to take an oak as a seedling, started it very young, you could do it.”

Through Aug. 2, the museum is exhibiting the winners of a contest of bonsai containers. There were categories for different types of pots, including round, cascade, containers for shohin (bonsai 4 to 10 inches tall) and those for kusamano (wild grass and flower arrangements). The direct translation of bonsai is “tree in pot.” This exhibit, in which pots are displayed without bonsai, showcases the pottery.

Joe Gutierrez of McLean, a retired surgeon who volunteers at the arboretum every Thursday, said the pots represent the skill and artistry involved in creating a vessel for the trees, given the variation in requirements for different varieties of tree: size, degree of wiring, moisture level of the soil.

“The more ornamental the tree is, the more variation one has in terms of the style of the pot,” Gutierrez said. “Azaleas can have a more colorful type of pot. But the more stately, more masculine trees . . . you don’t want a pot that will take your attention away from the tree. The pot is a lot simpler. It’s like going to a party and the beautiful ladies are wearing beautiful gowns, and the men are all wearing tuxedos.”

Gutierrez, who maintains about 100 bonsai trees in his back yard, is a member of the Northern Virginia Bonsai Association. The group has about 75 members and meets monthly at Walter Reed Community Center in Arlington to talk about their hobby. Gutierrez attests to local bonsai enthusiasts’ passion for their hobby.

“I’m cutting on plants instead of people,” he said. “I enjoy working on plants, it keeps your fingers nimble.”

Sustic echoes the sentiment.

“I believe it helps you as a person if you get into bonsai,” he said. “It changes you, makes you a better person. It makes you more patient. It’s all about when they need the work done, not when I decide to do it. It’s a mutual training and mutual respect.”

Lanyi is a freelance writer.