At the end of my first year in college, I did odd jobs during the summer, including various types of yard work. On one occasion while cleaning dead leaves and debris from a shaded garden area, I noticed a peculiar, unpleasant odor. On checking to see where the odor was coming from, I noticed two or three "growths," about the width of a pencil and the length of a finger, rising above the surface of the ground. On closer inspection, I saw that these "growths" had the consistency and appearance of a sponge and the tips were partially covered with a slimy and putrid-smelling substance. The "growths" turned out to be fungi called stinkhorns (Fig. 19.13), whose odor attracts flies; the flies disseminate the sticky spores that adhere to their bodies.
Stinkhorns are interesting but relatively unimportant representatives of another large phylum of true fungi, the basidiomycetes (club fungi). Other members of this phylum include mushrooms (Fig. 19.14A), or toadstools (the only distinctions between mushrooms and toadstools are based on folklore or tradition, with edible species being called mushrooms
and poisonous species being called toadstools—mycologically, there is no difference), puffballs, earth stars (Fig. 19.14B), shelf or bracket fungi (Fig. 19.14C), rusts, smuts, jelly fungi, and bird's-nest fungi. They are called club fungi because in sexual reproduction, they produce their spores at the tips of swollen hyphae that often resemble small clubs. These swollen hyphal tips are called basidia (singular: basidium). The hyphae, like those of sac fungi, are divided into individual cells. These cells, however, have either a single nucleus or, in some stages, two nuclei. The crosswalls have a central pore (dolipore) that is surrounded by a swelling, and both the pore and swelling are covered by a cap. This cap, with some exceptions, blocks passage of nuclei between cells but allows cytoplasm and small organelles to pass through.
Asexual reproduction is much less frequent in club fungi than in the other phyla of fungi. When it does occur, it is mainly by means of conidia, although a few species produce buds similar to those of yeasts, and others have hyphae that fragment into individual cells, each functioning like a spore and forming a new mycelium after germination.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.