How did Mendel obtain purebred pea plants for his research?

Answer 1

Pisum sativum is visibly variable and is predominantly self-pollinated, which means different true breeding lines are easy to develop. People kept their own seed from each harvest so plants became inbred over time as they were selected for desirable traits from the wild progenitor (Pisum sativum ssp elatius). Plants had been selected over such a long time there were strains of domesticated pea (Pisum sativum) showing the characteristic features of domestication (e.g. smooth seed coats) clearly evident in archaeological sites that date back to 6500 BC.

Mendel worked as a gardener so was used to the varieties of pea in common cultivation. He used the monastery’s garden for his experiments so he may have used their peas.
Wild peas have pods that open to spill the seeds. They have dormancy period. They are tall with many basal branches. The seeds have poor taste color and texture. They're flowering is triggered by long day length. Domestic peas do not have pods that open and dormancy is lacking. The plants are dwarf with few basal branches. The seed quality is superior in taste, color and texture. Flowering is day neutral.
Do any of these traits sound familiar? Tall versus dwarf, Seed wrinkled versus round.
Mendel was working with the traits that form the basis of pea domestication from the wild type.

Answer 2

He would take some seeds and interbreed them. At one point if you have all one color show up 2 generations in a row, you don't have the opposing gene . In other words, the seed is homozygous for that trait.