Somatic embryogenesis from leaf midrib explants of Dendranthema grandiflora Tzvelev. `Iridon' cultured on modified Murashige and Skoog basal medium (MSB) containing 1.0 mg 2,4-D and 0.2 mg BA/liter was influenced by light and sucrose concentration. Somatic embryos formed directly from explants when cultured on medium containing 9% to 18% sucrose and incubated first in the dark for 28 days, followed by 10 days in light, and then returned to the dark for 14 days. Embryogenesis did not occur in continuous darkness and was drastically reduced when explants were incubated in light only. The most embryos were formed on medium containing either 12% or 15% sucrose; lower concentrations stimulated shoot and root development. Light also mediated embryogenesis from leaf explants of 'other cultivars. White-opaque or occasionally light-green cotyledon-stage somatic embryos germinated on MSB medium without growth regulators but containing 3% sucrose. Twelve of the 23 cultivars evaluated produced somatic embryos, but plants were recovered from only five. Regenerated plants were phenotypically similar to parent plants in growth habit, leaf morphology, and flower color. Chemical names used: N- (phenylmethyl)-1 H- purine-6-amine (BA); (2,4-dichlorophenoxy) acetic acid (2,4-D).