The effects of continuous soil hypoxia on stomatal conductance (g^ and net photosynthetic rate (P^) ů* seedlings of Taxodium disíichum, Quercus lyrata, and Q. falcata var. pagodaefolia were studied under controlled environment. Soil oxygen deficiency induced significant stomatal closure and reduction of in oak species within 1-3 d. This response pattem continued resulting in average daily values of g^ reduced 85 and 40 % within 14 d in g. falcata and Q. lyrata as compared to control plants, respectively. Ehiring the same period Pn reduced 96 and 71 % in 0. falcata and Q. lyrata as compared to control plants, respectively. In T. distichum, however, gg and Pff were reduced 18 and 33 % by day 8. Significant recoveiy of gg and was noted in T. distichum. By day 14, gg had recovered to 91 % and to 92 % of control plants. In oak species, however, remained significantly lower than in control plants without any apparent recovery. The regain of photosynthetic activity and stomatal functioning in flood-tolerant species appears to be an important flood- tolerance characteristic allowing these species to fimction under flooded soil.