The occurrence of stromacentre in chloroplasts ofAsplenium trichomanesL. is reported. Such structure, so far described by GUNNING and coworkers in some species ofAvenaand by FAVALI and MEYER inOcymum basilicumL, has been found to occur in all stages, from the young to senescent ones, ofAsplenium trichomanes.The stromacentre inA. trichomanesis similar in shape to those ofAvena sativaandOcymum basilicum, but differs from these mainly for the size of its component fibrillar units. The value of both diameter and longitudinal periodicity is in fact 85–90 Å inAvenaandOcymum, whereas inAsplenium trichomanesvalues of 170–180 Å for the diameter and ca. 110 Å for the longitudinal periodicity have been observed. Preliminary investigations on other species of the genusAspleniumhave shown that the stromacentre also occurs on chloroplasts ofA. virideHuds.