Bridging crosses between plants
Bridging crosses between plants means the utilization of an intermediate plant in a cross to produce a viable zygote between the intermediate plant and a first plant, in order to cross the plant resulting from that zygote with a third plant that would not otherwise be able to produce viable zygotes from the fusion of its gametes with those of the first plant. The result of the bridging cross is the mixing of genetic material of the first and third plant through the formation of an intermediate zygote.
Source
40 CFR § 174.3
Scoping language
Terms used in this part have the same meaning as in FIFRA. In addition, the following terms have the meaning set forth in this section.