Certified Seed has different classes of seed to fit each type of seed grown. The classes ensure genetic purity, and are described as follows:
Breeder Seed (White Tag)
Breeder seed is very limited in amount and is directly produced or controlled by the originating plant breeder or institution. This seed is normally not available in commercial channels. Breeder seed provides the source for the increase of Foundation seed.
Foundation Seed (White Tag)
Foundation seeed is multiplied from breeder seed and is grown under the supervision of a Foundation Seed Program of either the public or private institution controlling the variety.
Registered Seed
Registered Seed is the progeny of either Breeder or Foundation seed. Registered seed is available in regular market channels and is normally required to produce certified seed. Many perennial crop varieties do not have a registered class specified
Certified Seed
Certified seed is the most commonly encountered certified seed and is the large-volume class sold to farmers for producing a commercial crop of the variety. It is the progeny of either Foundation or Registered seed stock. Under certain circumstances the progeny of Certified seed can be recertified as long as the genetic identity, varietal purity and other standards are maintained.
Source Identified Seed
Source Identified class is seed or other propagating materials collected from natural stands or produced in seed fields where no selection or testing of the parent population has been made. When seed is collected from a natural stand, the generation is G0.
Taken in part from the UCIA website.