Mendel followed the inheritance of 7 traits in pea plants (Pisum sativum). He chose traits that had 2 forms:
- Pea shape (round or wrinkled)
- Pea colour (yellow or green)
- Flower colour (purple or white)
- Flower position (terminal or axial)
- Plant height (tall or short)
- Pod shape (inflated or constricted)
- Pod colour (yellow or green).
Mendel began with pure-breeding pea plants because they always produced progeny with the same characteristics as the parent plant. Mendel cross-bred these pea plants and recorded the traits of their progeny over several generations.