摘要：Pteridium aquilinum (L.) Kuhn (Pteridophyta, Filicopsida, Hypolepidaceae) a species known by the common name of brakenfern, vegetates in meadows, on forest outskirts and in deforested plots. The vegetal material studied, i.e. leaves of the brakenfern, was collected in the village of Meri ani, in the Arge district, from specimens belonging to two different populations, one that vegetates in a meadow, in the sunlight (heliophile population), and another one from a forest (sciadophile population), at a distance of cca. 100 m. The different environment of the Pteridium aquilinum populations has induced modifications regarding the dimension of the populations, the sexuate reproduction, the anatomy of the leaves. The forest population is numerically smaller, does not reproduce in the sexuate way, and presents smaller thickenss of the lamina, of the hypodermic sclerenchyma cells and the stomata; correspondingly, on the lower part of the leaf there are three times fewer stomata than in the individuals vegetating in the meadow. The meadow population is made up of numerous individuals, it reproduces in the sexuate way and has larger dimensions of the lamina thickness, of the hypodermic sclerenchyma cells and the stomata. In order to observe the evolution of the two populations, it is necessary that they be further monitored
