Abstract:The stomata on the seed coat, a rare character of angiosperms, is reported on Homalanthus populifolius Graham for the first time, which is distributed in northeast and north of Australia. The stomata on the seed coat were compared with those on the leaf. The research history, morphology, development, physiology function and evolutionary implications of this rare character were reviewed. The hypothesis was proposed that the stomata may be the relic of the outer integument as a leaf structure, and the future research direction was prospected.