Palm Tree Caulerpa (Caulerpa paspaloides) is a prolific green macroalgae that looks great and grows slower than other members of the caulerpa family, and is much less likely to overrun your tank. This makes it an ideal piece for the display tank in addition to the sump/refugium. It will grow well under 2 watts per gallon full spectrum lighting or better. 4 or more with efficient lighting in a shallow tank for best refugium results.
The macro grows from a "runner", a common name for the root systems that grows along the substrate. The plants grow up from the runner. You can create multiple plants by removing the runner intact from your tank, clipping it in an area that is between two plants and reattaching the new runner to liverock or a different substrate. This macro can be safely superglued, or tied down with fishing line to hold it in place.
This species of Caulerpa can be shipped to California, outside of San Diego.