Mendel studied the following genes (the dominant trait is given first). Chromosome 1: Purple/white flowers; Yellow/green peas. Chromosome 4: Axial/terminal flowers; Tall/short plant; Inflated/ constricted pods. Chromosome 5: green/yellow pods. Chromosome 7: Round/wrinkled seeds Related Theory Mendel studied inheritance in peas (Pisum sativum). He chose peas because they had been used for similar studies, are easy to grow and can be sown each year. Pea flowers contain both male and female parts, called stamen and stigma, and usually selfpollinate.