This project investigates the effects of leaf side, leaf position, individual plant, and hill (or plant group) on phytolith assemblages from Zea mays L. cultivar Mandan Yellow Flour. Thirty-two samples were examined, and 200 phytoliths were classified from each sample. Statistical analysis indicates that leaf side is significant at the 0.05 level above random counting variation; leaf position, individual plant, and hill are not generally significant beyond the effect of leaf side. Analysis of a single sample, either a half or entire leaf, is not sufficient for compilation of representative phytolith assemblages from a plant population. Phytolith reference collections should not be based on single samples of each species. Multiple samples from a population need to be analyzed to obtain information on assemblage variation within the population. The variation of corn phytolith assemblages in this study overlaps those of many Panicoid grasses, indicating that additional morphological characters need to be identified to distinguish corn from wild grasses in the Great Plains. Key words: phytoliths, corn, frequencies, variation.