The quite possibly wise P van Rijckevorsel was heard saying:
Rubus is both rather variable and a taxonomic nightmare.
A picture like this seems a fair match

http://www.arborea.se/rubodor.htm

Colin Wetherbee schreef in
This looks like the closest match yet. Thanks!

Colin

According to a field guide there is only one Rubus species in California
with non-compound and 5- lobed leafs:

http://www.fw.vt.edu/dendro/dendrolo...arviflorus.htm
PvR