Ian,

This probably is the summer flowering tamarix, Tamarix chinensis that blooms from late June through September. Mine finished blooming in July.

It is listed in Washington State as a Class B weed under its other often used scientific name: T. ramosissima. Jacobson says it isn't a problem in Western Washington and Seattle, http://www.arthurleej.com/p-o-m-June05.html . Even though an expert like Jacobson says it isn't a problem, there will be people who because it is listed will say it has to go.

It is a beautiful bush/tree, especially with that windmill palm and the rose that looks like a Bougainvillea with the looks of the house. A Mediterranean look!

If you have not already, look in Trees of Seattle - Second Edition to see if that helps.

...on the state level don't differentiate between eastern and western Washington. We can't therefore plant Centaurea macrocephala here anymore because of a single large outbreak in eastern Washington. I can't see Gypsophila paniculata spreading like wildfire in western Washington either.

Thanks. I did look in Trees of Seattle. I guess I'm a little surprised to see this tree, if it is T. chinensis/ramosissima, in full bloom that early in such a cool spot. But it does enjoy a south facing, sunny aspect. There are a few other Trachycarpus in this neighborhood, which all look horrible. Lots of salt wind and not enough water/good soil (except for this example, it seems). I think this place looks pretty good too although I'm not quite sure what that rock is all about. And the bird's-nasty-spruce could be replaced with something more interesting.

I'll have to figure out if there are any Tamarix cultivars resembling this plant that I could propagate and sell in a legal and uncontroversial manner.

Like other popular garden plants the spruce is excellent in a suitable spot. In the location shown they are shearing them to keep them in a too narrow space, where a taller plant is needed to grow up in front of the glaring white wall, around the palm. It would be best to have more than one kind.