Common name: Dwarf Palmetto, Bluestem Palmetto, Blue Palm
Plant Link: http://plantsdatabase.com/go/57398/
I agree with Palmbob (See Gardener's Notes) in that this is not a plant for the warm, dry climate of Southern California. I lived in California for over six years, and have lived in the Southeast US for many, many years, and the climates are almost opposites, in that the Southeast is colder in the winter, even Florida, and of course rather rainy and humid almost all year round. In a favorable habitat this small palm tree is a deep bluegreen in color, and requires only an annual pruning of old brown fronds to look nice. There is a trunk, but I understand from my reading that it grows underground as deep as five feet! Quite unusual. Of course it's claim to fame is its legendary coldhardiness, and therefore it can be grown where no other palms will grow. Even here in Northcentral Florida we have very few palms due to our occasional winter deep freezes that last for a few days. And I could see that it would be just the thing for England's cool and wet climate.
I have done a lot of research on this plant because I have a lot of them growing on my property, perhaps as much as a quarter acre, and I was not very familiar with the plant before. Of course I had seen them around in the Southeast, but had never paid any real attention to them, and didn't realize they were different from the "scrub palmetto," Sabal etonia, which by the way can look very scruffy here in Florida.