This section is from the book "Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc.", by George Francis Atkinson. Also available from Amazon: Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc..
Most of the stink-horn fungi are characterized by a very offensive odor. Some of them at maturity are in shape not unlike that of a horn, and the vulgar name is applied because of this form and the odor. The plants grow in the ground, or in decaying organic matter lying on the ground. The spawn or mycelium is in the form of ropelike strands which are usually much branched and matted together. From these cords the fruit form arises. During its period of growth and up to the maturity of the spores, the fruit body is oval, that is, egg form, and because of this form and the quite large size of these bodies they are often called "eggs." The outer portion of the egg forms the volva. It is always thick, and has an outer thin coat or membrane, and an inner membrane, while between the two is a thick layer of gelatinous substance, so that the wall of the volva is often 3-6 mm. in thickness, and is very soft. The outline of the volva can be seen in Fig. 215, which shows sections of three eggs in different stages. Inside of the volva is the short stem (receptacle) which is in the middle portion, and covering the upper portion and sides of this short stem is the pileus; the fruit-bearing portion, which is divided into small chambers, lies on the outside of the pileus. In the figure there can be seen cross lines extending through this part from the pileus to the wall of the volva. These represent ridges or crests which anastomose over the pileus, forming reticulations. The stem or receptacle is hollow through the center, and this hollow opens out at the end so that there is a rounded perforation through the upper portion of the pileus.
The spores are borne on club-shaped basidia within the chambers of the fruit-bearing portion (gleba), and at maturity of the spores the stem or receptacle begins to elongate. This pushes the gleba and the upper part of the receptacle through the apex of the volva, leaving this as a cup-shaped body at the base, much as in certain species of Amanita, while the gleba is borne aloft on the much elongated stem. During this elongation of the receptacle a large part of the substance of the gleba dissolves into a thick liquid containing the spores. This runs off and is washed off by the rains, leaving the inner surface of the gleba exposed, and showing certain characters peculiar to the various genera.
Among the stink-horns are a number of genera which are very interesting from the peculiarities of development; and some of which are very beautiful and curious objects, although they do possess offensive odors. In some of the genera, the upper part of the plant expands into leaf-like - or petal-like, bodies, which are highly colored and resemble flowers. They are sometimes called "fungus flowers."