The Mushrooms Formerly Known as Dentinum Repandum This article will cover a description of Hydnum repandum, its ecology, and some research involving the species. The first topic to be discussed in this article is a description of Hydnum repandum, until recently referred to as Dentinum repandum. The description of the fungi will begin with the appearance of H. repandum, and will be followed by the life cycle of the reported species. The appearance of Hydnum repandum is quite unique. The mushroom stem can vary from two to seven centimeters in height and from one to three centimeters in thickness (Wood). The surface of the stem can vary from cream to yellow, it is dry and smooth. The mushroom cap is two to ten centimeters wide, with a smooth, dry surface (Graham 84). The color of the caps can vary from cream to orange. It has thick pulp that is very fragile, with a delicate flavor and odor. The hymenophore has teeth 0.4 to 0.6 centimeters long. They are cream colored, and also fragile (Wood). The life cycle of Hydnum repandum is quite simple, as you can see from Figure 2. It falls into the subdivision of the Eumycota, called Basidiomycotina (Ross 18). This group contains many large, fleshy mushrooms. To begin this discussion of the life cycle of Hydnum Repandum, this text will begin with the germination of the basidiospores (Webster 295). This results in a haploid mycelium with a single nucleus in each cell. It is therefore referred to as a monocaryon or primary mycelium (Ross 141). Subsequently, two genetically different thalli merge and the nuclei move from one thallus to the other. Migration of the nuclei usually causes both thalli to become dikaryotic (Ross 142). This nuclear migration is very rapid and each hyphal tip becomes binucleate. Subsequent growth of the fungus is all dikaryon (Ross 143). The next step involves fusion of the two nuclei of the dikaryon through the karyogomy (Ross 146). The resulting diploid zygotic nucleus then undergoes meiosis, and four haploid nuclei are formed in the basidium (Webster 280). The haploid nuclei move into projections on the basidium, which transform into spores. The spores remain attached to the sterigmata until they are released (Ross 146). The cycle then starts all over again. The next topic of discussion in this article is ecology. This will include preferred habitats and interactions with abiotic and biotic elements of the environment.