Abstract: Appearance of small initials of Gyromitra esculenta (Pers.) Fr. was studied in a Central Finnish spruce forest in connection of semi-cultivation experiments. An earlier report on the occurrence of autumnal initials was confirmed. The small initials were marked and their development was followed by photographing them in both the autumn and spring. These nodules were as small in December as the nodules two years earlier in October. The initials developed into young fruit bodies under the snow in spring, but not during an unusually warm autumn. The observations support the theory that the fruit body production is regulated by a mycochrome-like pigment depending on day length.