This is I'm pretty sure a Montanoa. The flower is very similar to M. leucantha, M. grandiflora and M. guatemalensis, but I don't think any of them have the auricles at the base of the leaf. Both M. hibiscifolia and M. bipinnatifida have such auricles, but I think the leaves of the latter are very deeply lobed (hence the name) and pictures I've seen online of hibiscifolia have shown both white and yellow flowers so I'm not sure whether those are correct identifications. It would be unusual I think for an Asteraceae to have both white and yellow forms of the same species. Some of the leaves of this plant seem not to be very lobed at all and others are mildly lobed. If anyone is familiar with any of these species and can either confirm or eliminate any of them as a possibility, please let me know. The LA Arboretum has all five in its accession records, so it's probably one of them, but that's not a certainty. I'll post sevral pictures.
Well, I hope someone with better availability to references can pick this one up. It looks like this might be needed: http://orton.catie.ac.cr/cgi-bin/wx...ost&formato=2&cantidad=1&expresion=mfn=014197
