Callus Cultures
Callus is an undifferentiated mass of tissue which appears on explants within a few weeks of transfer onto growth medium with suitable hormones [34]. Callus formation occurs from revered process of cell differentiation, known as dedifferentiation or redifferentiation [35]. Different growth hormones are used to promote callus induction and development. In Cephaelis ipecacuanha 2, 4-D and NAA along with kinetin promoted callus induction and growth [57]. New plants can be successfully regenerated from callus through organogenesis [58].