416. The black fungi.—These are very common on dead logs, branches, leaves, etc., and may be collected in the woods at almost any season. The perithecia are often numerous, scattered or densely crowded as in Rosellinia. Sometimes they are united to form a crust which is partly formed from sterile elements as in Hypoxylon, or they form black clavate or branched bodies as in Xylaria. The black knot of the plum and cherry is also an example.
The lichens are mostly ascomycetes like the black fungi or cup fungi, while a few are basidiomycetes.
417. The morels (Morchella).—There are several species of morels which are common in early spring on damp ground. Either one of the species is suitable for use if it is desired to include this in the study. [Fig. 231a] illustrates the Morchella esculenta. The stem is cylindrical and stout. The fruiting portion forms the “head,” and it is deeply pitted. The entire pitted surface is covered by the asci, which are cylindrical and eight spored. A thin section may be made of a portion for study, or a small piece may be crushed under the cover glass.
418. The cup fungi.—These fungi are common on damp ground or on rotting logs in the summer. They may be preserved in 70 per cent alcohol for study. Many of them are shaped like broad open cups or saucers. The inner surface of the cup is the fruiting surface, and is covered with the cylindrical asci, which stand side by side. A bit of the cup may be sectioned or crushed under a cover glass for study.
Mushrooms
(Basidiomycetes).
419. The large group of fungi to which the mushroom belongs is called the basidiomycetes because in all of them a structure resembling a club, or basidium, is present, and bears a limited number of spores, usually four, though in some genera the number is variable. Some place the rusts (Uredineæ) in the same series (basidium series), because of the short promycelium and four sporidia developed from each cell of the teleutospore.
420. The gill-bearing fungi (Agaricaceæ).—A good example for this study is the common mushroom (Agaricus campestris).
This occurs from July to November in lawns and grassy fields. The plant is somewhat umbrella-shaped, as shown in [fig. 232], and possesses a cylindrical stem attached to the under side of the convex cap or pileus. On the under side of the pileus are thin radiating plates, shaped somewhat like a knife blade. These are the gills, or lamellæ, and toward the stem they are rounded on the lower angle and are not attached to the stem. The longer ones extend from near the stem to the margin of the pileus, and the V-shaped spaces between them are occupied by successively shorter ones. Around the stem a little below the gills is a collar, termed the ring or annulus.
Fig. 232.
Agaricus campestris. View of under side showing stem,
annulus, gills, and margin of pileus.