Art historians had known of the Van Gogh drawing, stored at the Van Gogh Museum in Amsterdam. But they had always wondered whether it was a copy of a completed painting.

Now, at last, the painting itself has been discovered — concealed under another painting in the Museum of Fine Arts in Boston, the Van Gogh Museum said Friday.

The work, "Wild Vegetation," painted in June 1889, was discovered in an X-ray of "The Ravine," which Van Gogh painted on the same canvas four months later, the museum said.

"One of our specialists looked at the X-ray and recognized it as resembling a drawing from the museum," said Natalie Bos, a spokeswoman for the Van Gogh Museum.

The museum called the discovery important for researchers and said it would display the drawing, done in brown reed pen, in Amsterdam starting next week as part of an exhibition of Van Gogh's drawings running until Oct. 7.

Coincidentally, the discovery came at the same time that a team from the Van Gogh Museum concluded that a painting in Australia's National Gallery attributed to the Dutch master for more than 70 years was not a true Van Gogh. Experts concluded that strong stylistic differences indicated it probably was painted by a contemporary.

The painting, "Head of a Man," was brought to Australia in 1939 as part of an art exhibit owned by Keith Murdoch, father of media mogul Rupert Murdoch.

In the case of "Wild Vegetation," Vincent Van Gogh often sent drawings of his painted works to his brother Theo, an art dealer in Paris. The artist, who sold few paintings during his lifetime, relied on Theo to send him supplies, and painted new compositions over his old work if the materials arrived late and he lacked the money to buy his own.

At the time "Wild Vegetation" was painted, Van Gogh was confined at the Saint-Remy asylum in southern France. Armed with fresh materials from Theo, he was allowed off the hospital grounds and painted the surrounding landscape, including his famous series "Wheatfields."

The painting was done in a wide range of colors. But the two-toned swirls of the drawing, which has been in the Amsterdam collection, though not on display, disclose little of the vibrancy of Van Gogh's painted works.

Van Gogh, whose career spanned just 10 years, shot himself to death in 1890.

A report on the discovery by Louis van Tilborgh, a curator at the Van Gogh Museum, and Meta Chavannes at the Boston museum is being published this week in The Burlington Magazine, a leading art journal.

In the other Van Gogh-related finding, “Head of a Man” became stranded in Australia with the outbreak of World War II, and the gallery bought it in 1940 for around $3,500.

"It was purchased as a Van Gogh work, and had been accepted as a Van Gogh for more than a decade before the (gallery's) purchase," Vaughan said in a statement.

He stressed the painting had simply been misattributed to Van Gogh.

"It is very important to make the point that it's not a forgery," he told reporters. "There is no evidence to suggest that someone produced this picture ... to pass it off as a work by Van Gogh."

The painting's authenticity was first called into question last August when it was on show at the Dean Gallery in Edinburgh, Scotland. Critics said the work, dated 1886, was of a different style to other Van Gogh paintings of the same period and was not mentioned in any of the Dutch master's letters.

When the exhibit closed, the National Gallery of Victoria sent the painting — a portrait of a bearded, curly haired man against a brownish background — to the Van Gogh Museum in Amsterdam for verification.

As a Van Gogh, the painting had been valued at around $21 million.