But Sunnyvale's tree preservation ordinance, established to save mature trees of significant size, prevents them from doing so. Now the three residents have petitioned the planning commission for permission to cut down six trees.

According to the ordinance, a tree must meet one of three criteria in order to be taken down. The tree must be diseased or badly damaged; it must represent a potential hazard to people, structures or other trees; or it must restrict the owner's ability to enjoy the use or economic potential of the property on which the tree is located.

The planning commission met on March 10 and granted Hoffacker permission to cut down two Melaleuca trees in her backyard only if she could provide proof, possibly in the form of an allergy scratch test, that either Hoffacker or her neighbors are allergic to bees. Hoffacker argues that the Melaleuca tree's flowers attract bees in the spring. City arborist Steve Sukke agreed.

Hoffacker said at the meeting that she is allergic to bees and that sometime in the 1980s she was stung by a bee and her arm swelled up. She was unable to provide proof of her trip to the hospital because the hospital does not keep records of minor visits from that long ago.

Her neighbor, Andy Brockman, also spoke in favor of cutting down the two trees. Brockman said he's allergic to bees as well, and though he did not have a medical statement to that effect, he did produce a letter he had written to his mother from summer camp at the age of 8. In the letter he said he had been stung by a bee and received treatment because he was allergic to bees.

"I also have two small children, and I'm concerned that they have the same allergy," Brockman said.

The commission decided that they would approve the removal of the trees only upon proof of an allergy to bees and denied a request for the removal of a camphor tree in Hoffacker's front yard because it did not meet the requirements for removal.

But Harry and Laura May did not have the same luck. The commission denied their request to remove three Monterey pine trees in the couple's front yard.

Harry May said the trees were a danger to his family because the trees are only 15 feet from the house and there's a risk they might fall onto the house during a storm.

But arborist Sukke said the likelihood that any of the trees would fall onto the house is negligible, especially because the trees survived a major storm last December.

May said, "The probability of such an event is not zero." He said that in the event any of the trees do fall over the city must assume liability if they do not grant permission to cut the trees down. But the commission did not grant permission and assumes no liability, according to the city attorney present at the meeting.

Planning Commissioner Megan Satterlee said, "One of the things that distinguishes Sunnyvale from its neighbors is the amount of trees it has." Satterlee said that the preservation of trees cuts down on pollution, preserves oxygen and provides cool shade for the sidewalks around them.