Too short on cash to check out expensive museum exhibits at the de Young or SFMOMA? Get your art fix, gratis, by heading over to Civic Center Plaza. The SF Arts Commission just announced the extension of the public art project by acclaimed environmental artist Patrick Dougherty. Comprised of 4,500 pounds of freshly cut willow saplings from The Willow Farm in Pescadero (some more than 50 years old) interwoven into the treetops of the sycamore trees in Joseph L. Alioto Performing Arts Piazza of Civic Center Plaza, The Upper Crust is the artist’s first project in San Francisco. Rising eight feet above the treetops, the cocoon-like forms inspired by City Hall's rotunda were created without an internal structure, wire, hardware or any outside means of attachment and independently entangle and intertwine with everything around them. As the holiday lights twinkle on the big tree in Union Square, contemplate the stark contrast of Dougherty's silently growing piece as it evolves over the season.

The Upper Crust will be on view at Civic Center Plaza through February 2010. The Arts Commission provides a free docent tour for the public on the first Tuesday of every month from 12 - 1 p.m..