ABSTRACTDecrease in osmotic potential of growth media resulted in changes to vesicle and conidial morphology inCylindrocladium scoparium, C. floridanumandCylindrocladiella camelliae.Radial growth and the presence of chlamydospores also decreased for these species when the osmotic potential of the growth medium was decreased. Vesicle shape varied on different culture media as well as with age and conditions of incubation. Extended incubation periods induced a change in osmotic potentials of the culture media directly influencing vesicle shape. Carnation-leaf agar is proposed as a standard medium for the characterization of morphological criteria inCylindrocladiumandCylindrocladiella.Moreover, an incubation period of 7 days at 25 C under alternating light and dark cycles is proposed for vesicle examination.