441. Order Hemiascales (Hemiascineæ).—Fungi with a well developed, septate mycelium, but with a sporangium-like ascus, i.e., a large and indefinite number of spores in the ascus. Examples: Protomyces macrosporus in stems of Umbelliferæ, or P. polysporus in Ambrosia trifida. These two are by some placed in the Ustilagineæ. Dipodascus albidus grows in the exuding sap of Bromeliaceæ in Brazil and the sap of the beech in Sweden. The ascus is developed as the result of the fertilization of an ascogonium with an antheridium (see [fig. 251]).
2. SUBCLASS PROTOASCOMYCETES.
442. The asci are well-defined and usually with a limited and definite number of spores (usually 8, sometimes 1, 2, 4, 16, or more). Mycelium often well developed and septate. Asci scattered on the mycelium, not associated in definite fields or groups.
443. Order Protoascales (Protoascineæ).—The asci are separate cells, or are scattered irregularly in loose wefts of mycelium. No fruit body. (The yeast, Saccharomyces, [see paragraph 237]; and certain mold-like fungi, some of which are parasitic on mushrooms, as Endomyces, are examples.)
3. SUBCLASS EUASCOMYCETES.
Asci associated in surfaces forming a hymenium, or in groups or intermingled in the elements of a fruit body. Fruit body usually present.
The following four or five orders comprise the Discomycetes, according to the usual classification.
444. Order Protodiscales (Protodiscineæ).—The asci are exposed and form large and indefinite groups, but there is no definite fruit body. Examples: leaf curl of peach, plum pocket, etc. (Exoascus).
445. Order Helvellales (Helvellineæ).—The asci form large fields over the upper portion of the fruit body. This order includes the morels ([fig. 231a]), helvellas, earth tongues (Geoglossum), etc.
446. Order Pezizales (Pezizineæ).—The asci form a definite field or fruiting surface surrounded on the sides and below by a wall of fungus tissue, forming a fruit body in the shape of a cup. These are known as the cup fungi (Peziza, Lachnea, etc.).