The histogenesis of Bulb and trama tissue of the higher Basidiomycetes and its phylogenetic implications

At the base of the stipe in Agaricales basal plectenchyma is found which may enlarge to form a bulb. This tissue is not homogeneous. It is characterized by peculiar configurations: free tips of branches, sinuous hyphae, loops, spirals and rings (sometimes enclosing another hypha) and hyphal knots. The hyphal knots present themselves as bundles of hyphae, which may or may not be the centre of cell division, or as agglomerations of cells surrounded by coiled hyphae. The latter structure, present in many species of Agaricales, is found in its perfect form in the trama of the Amanitaceae, which recalls the trama of the Russulaceae. The young pileus trama of many species shows the same characteristics; these also occur in the trunk of Ramaria, in young bulbs of Gasteromycetes, and in various veils. The diverse kinds of cell formation in the primordia of Agaricales are treated at some length, the conception meristemoid is defined, and a comparison with the development of some of the true Aphyllophorales is made. The heteromerous trama of the Asterosporales and the trama of the Amanitaceae, characterized by acrophysalides, are considered to be derived from the young trama of other Agaricales. The tissue of the bulbs of the strains 59b and 59c of Agaricus bisporus is analyzed. Strain 59b is homologous with the bulb tissue of a normal fruitbody of Agaricus bisporus. In agreement with G. Fritsche the conclusion is drawn that 59c is a gigas-form. Watling’s carpophoroids of Psilocybe merdaria are considered. The fundamental differences between the development of true Aphyllophorales and that of cantharelloid fungi, Agaricales, and Gasteromycetes are emphasized. As for the evolution within the Asterosporales, it is concluded that the degradation of certain characters in the gasteromycetoid forms (Heim, Malençon) need not contradict the arguments advanced by R. Singer and A. H. Smith.