If you haven't yet gotten the chance to explore the expansive collection of trees and plants on the rooftop of the Transbay Transit Center (a.k.a. Salesforce Park at the Salesforce Transit Center), you now have the chance to do so again.

The building and park reopened last month, complete with the gondola/funicular thing that was not operating last year when the Transit Center originally opened. And local tree expert Mike Sullivan, author of the guidebook The Trees of San Francisco, says he realized "there was something special going on" up in Salesforce Park when he spotted a monkey puzzle tree from the street.

He tells Hoodline it drew him up to the park immediately and to speak with landscape architect Adam Greenspan, who led the design for the park. Greenspan explained how he created this miniature version of the San Francisco Botanical Garden, complete with Chilean, South African, and Mediterranean sections, as well as a "Fog and Wind Garden," and a "Cloud Forest."

Calling this park "the best collection of plants in San Francisco outside of the Botanical Garden," Sullivan has created a self-guided walking tour on his blog, which delves into some detail about the varieties of palm trees you'll find ("a ten-car pileup of different species"); Bay Area native trees like the California buckeye (Aesculus californica), strawberry trees (Arbutus X Marina), and California sycamores (Platanus racemosa ‘Roberts’); and rarities from across the oceans like the Queensland bottle trees (Brachychiton rupestris); and a Wollemi pine from Australia, of which Sullivan says there are fewer than 100 specimens alive in the wild.

After taking that tour with Sullivan's guide, you could also grab his book and do a tour of the city at large, which is home to plethora of beautiful tree specimens that he will point you to — like the New Zealand Christmas Tree at 17th and Stanyan that hit peak bloom in June.

You can also follow him on Instagram here.