Abstract: Viable heterotrophic cells growing in suspension cultures are heterogeneous in shape and size. Spherical, oval and elongated cell shapes were produced in suspension cultures of Peganumharmala grown in culture media supplemented with 2 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D). Spherical and oval cells grow through diffuse growth, while elongated cells grow by tip growth. Low alkaloid production rates were formed in these high growth rate heterogeneous cell populations. On subculturing suspended cells previously growing in liquid medium supplemented with 2,4-D to fresh medium without 2,4-D, a population of high alkaloid-producer idioblast cells were produced. Idioblasts were elliptical cells that have large central vacuole composed of β-carboline alkaloids and serotonin. They are growing through tip growth. The study discussed the development and maintenance of high quality cells growing in suspension culture that may produce efficient in vitro system for high alkaloid production.