Hedera helix on Eucalyptus globulus
Growing in Interior Park Belt, Sutro Forest, Mount Sutro. Host tree is Eucalyptus globulus.
The irony of two nonnative species from different continents holding probably the top two positions in an ecosystem on a third continent makes my head hurt.
The entire forest is owned by the University of California, San Francisco. The forest was planted by Adolph Sutro in the 1880s and is nearing end of life. It is reported that UCSF is studying what to do when that happens.