Growth and the chlorophyll and carotenoid contents were measured in greenhouse-grown yellow nutsedge (Cyperus esculentus L. ♯ CYPES), following treatment with glyphosate [N-(phosphonomethyl)glycine]. Herbicide was applied as a foliar spray at concentrations of 0.1, 1.0, 5.0, and 10.0 mM. After 2 weeks, growth was inhibited, and chlorosis and leaf apex necrosis were observed. Plant height was reduced, leaf fresh weight was decreased by 40%, and leaf dry weight was slightly affected. Rhizome, tuber, and secondary shoot formation was strongly inhibited, but root development was not affected by glyphosate treatment. With the 10-mM treatment, dry weight of the underground system was reduced by 80%. Chlorophyll and carotenoid levels were decreased by 52 and 54%, respectively, following glyphosate treatment.