Hi, I photographed these 2 Trilliums at Mount Usher Gardens in Co. Wicklow, Ireland. I hope there is a Trillium or N. American flora expert out there who can point me in the right direction.
There is a complex of Trlllium species of this type centered around the San Francisco Bay area that are told apart by fine botanical details, with it not being generally and certainly settled where one begins and another ends in the natural state. See specialist works on the genus.
Yes, important to keep in mind that the colour of the tepals is not a good ID characteristic (especially in cultivated situations). I think the complex Ron is referring to is the Trillium albidum / Trillium chloropetalum: see this page which concludes with discussion on hybridization between the two.
