=451. Order Perisporiales.=—The powdery mildews are good examples of this order (Uncinula, Microsphæra, etc., Chapter XXI). =452. Order Hypocreales.=[20]—The fruit bodies are colorless, or bright colored and entirely enclose the asci, sometimes opening by an apical pore. Nectria cinnabarina has clusters of minute orange oval fruit bodies, and is common on dead twigs. Cordyceps with a number of species is parasitic on insects, and on certain subterranean Ascomycetes, especially Elaphomyces (of the order _Plectascales_ = _Plectascineæ_). =453. Order Dothidiales.=[21]—Fungi with black stroma formed of mycelium in which are cavities containing the asci. The cavities are usually shaped like a perithecium, but there is no wall distinct from the tissue of the stroma (Dothidea, Phyllachora, on grasses). =454. Order Sphæriales.=[22]—These contain the so-called black fungi, with separate or clustered, oval, fruit bodies, black in color. The black wall encloses the asci, and usually opens by an apical pore. Examples are found in the black knot of plum and cherry, black rot of grapes, and in Rosellinia, Hypoxylon, Xylaria, etc., on dead wood. =455. Order Laboulbeniales (Laboulbineæ).=—These are peculiar fungi attached to the legs and bodies of insects by a short stalk, and provided with a sac-like fruit body which contains the asci. Example, Laboulbenia. III. Class Basidiomycetes. (The basidium series.) 1. SUBCLASS HEMIBASIDIOMYCETES. =456. Order Ustilaginales (Ustilagineæ).=—This order includes the well-known smuts on corn, wheat, oats, etc. (Ustilago, Tilletia, etc.). 2. SUBCLASS ÆCIDIOMYCETES. =457. Order Uredinales=[23] (Uredineæ).—This order includes the parasitic fungi known as rusts. Examples: wheat rust (Chapter XX), the cedar apple, etc. The true Basidiomycetes include the following orders: 3. SUBCLASS PROTOBASIDIOMYCETES. =458. Order Auriculariales.=[24]—This order includes trembling fungi in which the basidium is long and divided transversely into usually four cells (example, Auricularia), and similar forms. Pilacre petersii on dead wood represents an angiocarpous form. =459. Order Tremellales (Tremellineæ)=, trembling or gelatinous fungi with the globose basidium divided longitudinally into four cells (Tremella). 4. SUBCLASS EUBASIDIOMYCETES. =460. Order Dacryomycetales (Dacryomycetineæ).=—This order includes certain fungi of a gelatinous or waxy consistency, usually of bright colors. They resemble the Tremellales, but the basidia are slender and fork into two long sterigmata. (Example, Dacryomyces.) Gyrocephalus rufus is quite a large plant, 10-15 cm. high, growing on the ground in woods. =461. Order Exobasidiales (Exobasidiineæ).=—The fungus causing azalea apples is an example (Exobasidium). =462. Order Hymeniales (Hymenomycetineæ).=—In this order the basidia are usually club-shaped and undivided, and bear usually four spores on the end (sometimes two or six). There are several families.