Seed coat stomata of several Iris species

Seeds typically do not have stomata on their coats. Because some Iris species contain stomata, we studied those to characterize frequency and deduce possible stomatal functions in comparison with leaf stomata. We used scanning electron microscopy and statistical means to describe form and number of open versus closed stomata. Of the seven examined Iris species, I. laevigata Fisch., I. halophila Pall Walter and I. pseudacorus L. did not have stomata; I. ensata Thunb., I. mandshurica Maxim., I. dichotoma Pall, and I. giganticaerulea Small contained stomata in seed coats. Open stomata of these four species amounted to 82, 86, 90, and 24%, respectively. Stomata differed in shape and size; their frequency varied and was much lower than on leaves. Stomata of L giganticaerulea varied in size and shape and were round on seed coats and fruits but rectangular on leaves. The diversity of the stomata distribution, shape, and state indicates some physiological significance that may be relevant for the formation of the seed, composition of the seeds coat, dormancy, and water uptake during germination. (c) 2016 Published by Elsevier GmbH.