Chapter 18

THE STINK-HORN FUNGI: PHALLOIDEAE Fries.

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 rope-like 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."

DICTYOPHORA Desvaux.

=Dictyophora= means "net bearer," and as one can see from Fig. 212 it is not an inappropriate name. The stem or receptacle, as one can see from the illustrations of the two species treated of here, possesses a very coarse mesh, so that not only the surface but the substance within is reticulated, pitted and irregularly perforated. In the genus _Dictyophora_ an outer layer of the receptacle or stem is separated as it elongates, breaks away from the lower part of the stem, is carried aloft, and hangs as a beautiful veil. This veil is very conspicuous in some species and less so in others.

=Dictyophora duplicata= (Bosc.) Ed. Fischer.--This species is illustrated in Fig. 212, made from plants collected at Ithaca. The plants are from 15--22 cm. high, the cap about 5 cm. in diameter, and the stem 2--3 cm. in thickness. According to Burt (Bot. Gaz. =22=: 387, 1896) it is a common species in the Eastern United States. The cap is more or less bell-shaped and the sculptured surface is marked in a beautiful manner with the reticulations.

=Dictyophora ravenelii= (B. & C.) Burt.--This plant also has a wide distribution in the Eastern United States. The stem is more slender than in the other species, _D. duplicata_, the pileus more nearly conic, and the surface of the pileus is merely granular or minutely wrinkled after the disappearance of the gleba, and does not present the strong reticulating ridges and crests which that species shows. The plants are from 10 to 18 cm. high. It grows in woods and fields about rotting wood, and in sawdust. The veil is very thin and delicate, forming simply a membrane, and does not possess the coarse meshes present in the veil of _D. duplicata_. The Figs. 214, 215 represent the different stages in the elongation of the receptacle of this plant, and the rupture of the volva. This elongation takes place quite rapidly. While photographing the plant as it was bursting through the volva, I had considerable difficulty in getting a picture, since the stem elongated so rapidly that the plant would show that it had moved perceptibly, and the picture would be blurred.

In a woods near Ithaca a large number of these plants have appeared from year to year in a pile of sawdust. One of the most vile smelling plants of this family is the _Ithyphallus impudicus_.