Fruit body development of Amanita muscaria (Basidiomycetes)

Basidiome development of Amanita muscaria was examined with light microscop y and illustrated in line-drawings. The youngest primordium of a fruitbody of A. muscaria examined measures ca. 2 x 2 mm. At this stage, the primordia l universal veil and the primordial bulb are already outlined. At the top o f the bulb primordium, the hyphae are in an actively growing state and diff erentiate into stipe primordium and pileus primordium. With further develop ment of the primordial pileus, the primordium of the hymenophore appears, t hen the gills develop. At first, thin vertical plates appear radially in re gular distances in the hymenophore primordium. These plates consist of yell ow to brownish, more or less irregularly arranged, degenerating hyphae. The se hyphae are separated from vital hyphal segments by septa and disappear d uring the further development. Thereby the primordial gills are separated f rom each other. The vital terminal hyphal segments branch subterminally and regularly, thus forming the young hymenium. The gill differentiation proce eds radially away from the stipe or towards the stipe or in both directions . Hyphae at the gill edge are interwoven with those of the stipe volva duri ng the early fruitbody development, so that they appear to be connected to each other. The primordial universal veil surrounding the upper part of the fruitbody primordium ruptures and disappears early during the development. Thus there are no remains of the primordial universal veil on the mature p ileus. The white, yellowish warts on the pileus are derived from the pileal volva. The annulus originates from the stipe volva, which corresponds to t he so-called lipsanenchyma between the stipe and the hymenophor. Schematic illustrations of basidiome development in A. muscaria and A. phalloides are provided.