Its not a breeder or seedbank, clone only strains are only available as clones. Mostly they are special selected phenotypes of a commercial strain, or old classics who was keeped by someone somewhere...

Krome: “My strain "the white" has no relation to white widow to the best of my knowledge. It's called the white for one reason only. The color of the buds when finished. Looks like they were just rubbed in confectionary sugar or something. The real name of the strain is "Triangle." Got the name from being a 3 way cross. Has nothing to do with location, as I'm far away from Cali and to the best of my knowledge, it was born and raised in my home town. The triangle kush is another local strain that's been around for years. I really don't want to get into its origins as it always seems to start a heated debate.”