Here's an Aesculus Californica at Rancho Santa Ana Botanic Garden. This seems to be one of their favored trees, since I saw more than just the two in this blog post while wandering the trails on Jan 4. The one below was particularly striking from this angle with the agave in the foreground.
The A. californica below was particularly interesting because of the single small branch of early leaves. I incorrectly speculated a sport that had held onto its leaves later than most. RSABG gamely fielded my email question and wrote back, "Our Director of Horticulture noticed the very early new foliage too.... It's difficult to pin down the reason, but you could call it a sport," which only makes me more curious about the exact nature of the early foliage. I'd be out there vegetatively propagating it and naming it something like Aesculus californica 'Early arrival'.