There isn't much room for landscaping in the city's new transit mall, but an oak tree is nevertheless taking root in the midst of the downtown construction site.

Tile contractor Nick Tucker and Artstart artists have taken advantage of a lull in the renovation of the city's bus depot to install a large tile mural depicting the twisted limbs of a mature oak tree.

"It definitely changes the look of the whole place," Tucker said Monday as he stepped back to regard the hundreds of hand-painted tiles he has set in mortar so far.

The mural, which will cost about $50,000, was designed by local artist Mario Uribe. Its tiles were painted, glazed and fired by the young artists at Artstart, the nonprofit art program for teens.

The transit mall is undergoing a $3.1 million renovation to make it more inviting and easier to navigate.

The project got under way in June with the relocation of bus stops to First Street. The work was expected to be done by September, but fabrication delays have pushed that back to the end of October, said Jason Parrish, project manager.

The idea behind the mural and another art installation, a sheet-metal sculpture of a rose, was to bring a sense of the natural world into the urban hardscape, Parrish said.

"We still wanted to be able to provide that sense of the natural surroundings and the quality of the environment we live in," he said.