P: Parent Plants when beginning a cross. This is more of an arbitrary designation when beginning to breed a line to identify the two plants you started your project with. This will rarely be shown in this form on most commercial seed product. Many products that do include parentage will often cite “Mother” and “Father” for parent plants.

F1: The first Filial generation. A cross of two unlike parent plants. Term used for regular breeding of a natural female and a natural male plant.

      PFemale x PMale = F1

F2: The second Filial generation cross of two F1 progeny (offspring).

       F1 (Female) x F1 (Male) = F2

F3: The third Filial generation cross of two F2 progeny.

        F2 (Female) x F2 (Male) = F3 and so on for successive generations.

IBL: Highly stable cross, typically F5 or greater, with very little genetic diversity in progeny.

R1: First generation cross of two unlike parents (same as F1) but indicates the pollen donor was female (feminized).

       PFemale x PFemale Pollen Donor = R1 

S1:  “Selfed” Generation 1. Ultimate form of inbreeding. A feminized cross of a single plant bred into itself. This could be done with a single source plant that has some of its nodes feminized with the rest left to develop female organs naturally. The feminized branches will grow anthers and pollinate the remaining natural female organs (ovules within the pistils) producing seed that inherits its genome from a single genetic source instead of from two different genetic sources. Selfing can also be done via cloning the source plant and making either the clone or the source plant the pollen donor and the other the pollen receiver or by doing the same procedure with two clones from the exact same source plant.

P Source x P Source    /  P Source x P Clone    /  P Clone x P Clone = S1  

Bx:  Back cross. Label used when progeny is crossed back into one of its parents. 

   F1 (Female) x PMale  or  PFemale x F1 (Male) = Bx1 (Backcross 1)

RBx: Reverse Back cross. Same as backcross but with a female pollen donor instead of a natural male pollen donor. 

   F1 (Female) x PFemale Pollen Donor  or  PFemale x F1 (Female Pollen Donor) = RBx1 (Reverse Backcross 1)