Cranberry (Vaccinium macrocarpon Ericaceae Ait.) stomatal conductivity (SC) was investigated in the field to examine plant response as a function of weather conditions. Measurements were made during fruit maturation on 14 days between 0540 and 1710 h r, as weather conditions permitted. SC ranged from 0.02 to 0.08 cm·s-1 and was much lower than for most other crops. Scatter plots of SC vs. leaf temperature by day indicated only a weak linear relationship. When the data were stratified by time of day and by clear and overcast skies, several significant Pearson correlation coefficients suggested a stomatal response. The findings, when combined with current knowledge of the physical structure of cranberry stomata, suggest that cranberries behave as xeromorphic plants.