Enkele Opmerkingen over omgekeerde Hoeden op Agaricaceae en Cantharellaceae

Small inverted pilei on toadstools may arise in different ways. Probably the most common way is that in the beginning the bases and the pilei of two individuals fuse. Often one of the two individuals will be weaker than its “co-twin”, and then it may happen that, while growing in size, the stem of the weaker one breaks off at its base, so that its pileus is taken along with that of the bigger one. In most cases the smaller pileus shows a short stem (,~ Russula ochroleuca, Fig. 1). In the specimen of Russula ochroleuca shown in Fig. 2, that of Clitocybe nebularis (Fig. 3) and that of Russula fellea (Fig. 4) it looks as if the stem of the small toadstool tried to pull its pileus from the bigger one, but that it failed and broke, as the connection between the two pilei proved too strong. Cf. also the specimen of Laccaria laccata shown in Fig. 5. A second kind of “secondary” pileus is found in the specimen of Russula pectinata shown in Fig. 6, a, b, where we may accept a “proliferation”. The same may be the case in the degenerated pilei of Laccaria laccata (Fig. 7) and of Hygrophorus miniatus (Fig. 8). Deceptive is the specimen of Russula ochroleuca shown in Fig. 9. The secondary pileus seems to be inserted in the centre of the “mother pileus”, but on closer inspection the small pileus appears to be attached excentrically, so that it seems more plausible to assume that it arose in the manner described first. The rosettes or strips observed in Cantharellus cibarius (Fig. 10, a. b, c) probably arise from an incurvation of the margin of the pileus, followed by a fusing of the margins. If the rosettes or strips grow far from the margin, we must assume that at several places on the surface of the pileus a hymenium has been formed (cf. Fig. 11, Corlinarius anomalus). Sometimes the hymenium is formed below the surface and then the outer layer afterwards bursts, and the gills become visible (cf. Fig. 12, Corlinarius semisanguineus). In the latter case there were growing five toadstools close to each other, all with a crown of gills at the top of the pileus, and all apparently arising from the same mycelium. In the next year, however, all toad-stools found at this place were normal. In my opinion it is not allowed to call this anomaly a “mutation” or to speak of “heredity”, as some authors do, for there is no proof that in the next generations the abnormality will return. The same holds good with the sudden appearance in 1950 of 60 specimens of Clitocybe cerussata in a group of almost 300 showing in the middle of the pileus “morchelloid” fertile gills, whereas two other groups at a distance of about ten meters were normal. The toadstools grew at this place since 1946, and had always been normal. In 1951 one individual among 100 specimens showed a rosette of gills. The next years all Clitocybes were fully normal. This seems to me a still more striking proof that mutation does not play a part. What may have been the cause of the phenomenon remains unknown.