SAN FRANCISCO (Map, News) - William Shakespeare may have called the moon an “errant thief,” but it was likely a more earthly thief who stole two bronze plaques from The City’s Shakespeare Garden in Golden Gate Park.

Two of the garden’s six bronze plaques were stolen by an unknown suspect or suspects April 17 or 18, according to officers in the San Francisco Police Department’s Richmond District Station.

The plaques, donated before the bard-themed garden opened in 1928, feature different Shakespearean quotes describing different flora, according to historian and author Christopher Pollack. The garden is filled with flowers and plants that were named in the English playwright’s works.

Recreation and Park Department officials are working with the Police Department to investigate the theft, according to department spokeswoman Rose Dennis.

Golden Gate Park has been a frequent target for thieves, who have pilfered bronze pieces of the Ulysses S. Grant monument, purloined a bronze bucket from the Apple Press monument on the Music Concourse and snatched a plaque memorializing Domingo Ghirardelli in the 1970s, according to Pollack.

Other San Francisco parks have not been immune, either. A 160-pound bronze plaque memorializing the Armenian genocide, stolen from the peak of Mount Davidson in September, remains missing, according to Taraval Station Capt. Denis O’Leary. Burglary inspectors have declared the case inactive.

“The thief put a lot of effort into this — it’s a very large plaque, very heavy,” O’Leary said. “But the case remains unsolved.”

O’Leary said he believes whoever stole that plaque did so to sell it for the value of the bronze. Bronze is an alloy made of copper, whose value has risen to nearly $4 a pound.

It was nearly 30 years before the plaque memorializing Domingo Ghirardelli was hocked to a recycler about five years ago, according to Pollack.

“They can get melted down and disappear from history forever,” Pollack said.

bwinegarner@examiner.com