140 ] The Classification of Lower Organisms 



The Dothideales include Plowrightia morhosa, the agent of the black knot of 

 plums. Diseased twigs become swollen and covered with a black stroma which bears, 

 according to the season, conidia of various types or else perithecia. 



Order 8. Laboulbenialea [Laboulbeniales] Engler Syllab. ed. 3: 42 (1903). 

 Order Laboulbeniaceae Thaxter, the name (ascribed to Peyritsch) preoccupied 



by family Laboulbeniaceae Berlese in Saccardo Sylloge 8: 909 (1889). 

 Suborder Laboulbeniineae Engler in Engler and Prantl Nat. Pflanzenfam. 



I Teil, Abt. 1: vi (1897). 

 Class LabouJbeniomycctes Engler Syllab. 1. c. 

 Class Laboulbenieae Schaffner in Ohio Naturalist 9: 450 (1909). 



Parasites on insects, the mycelium scant or reduced to a single cell, producing 

 antheridia which discharge spermatia into the air and small numbers of perithecia. 



These organisms have the appearance of excep^^ional setae on their hosts, which 

 are not usually seriously injured by them. They were first mentioned in a note by 

 the entomologist Rouget, 1850; Montagne and Robin, in Robin's book on parasitic 

 plants, 1853, gave the first names, Laboulbenia Rougetii and L. Guerinii, the generic 

 name honoring the entomologist Laboulbene. Only a few scholars, notably Thaxter 

 (1896, 1908, 1924, 1926, 1931) have given much attention to this group; they have 

 distinguished well over a thousand species, forming three families and about fifty 

 genera. 



Many Laboulbenialea occur as two forms, male and hermaphrodite. A male indi- 

 vidual produces a series of flask-shaped antheridia, each of which discharges into 

 the air, one at a time, a series of globular naked sperms. A hermaphrodite individual 

 produces first a series of antheridia as described and then one or more perithecia. 

 A perithecium consists of a wall, of a definite number of cells produced in definite 

 order and pattern, surrounding an egg which bears a trichogyne; the trichogyne 

 protrudes from the perithecium and receives the sperms. The zygote gives rise to a 

 fascicle of asci which crowd aside and destroy the inner cells of the wall and dis- 

 charge the ascospores (usually eight in the ascus, and divided into two cells) through 

 the ostiole. 



Those who would link the Ascomycetes with the red algae entertain the hypothesis 

 that the Laboulbenialea represent the transition. This hypothesis is surely mistaken. 

 The Laboulbenialea are a highly specialized group, not a link between others. They 

 appear to have evolved from Sphaeriales with solitary perithecia. 



Class 3. HYPHOMYCETES Fries 



Classes Hyphomycetes and Coniomycctes Fries Syst. Myc. 3: 261, 455 (1832). 



Families Hyphomycetes and Coniomycctes Fries Epicrisis 1 (1836). 



Fungi imperfecti or Deuteromycetes Auctt. 



Inophyta of which the structures involved in sexual reproduction are unknown. 



It has been noted that a particular genus of Ascomycetes may produce conidia 

 of more types than one, as Sclcrotinia produces types called Monilia and Botrytis, 

 and Glomerella produces types called Gloeosporium. and Colletotrichum. The same 

 type may be produced by many genera; the Monilia type recurs in Neurospora, 

 which does not belong to the same order as Sclerotinia. Collecting naturalists, and 

 plant pathologists in the pursuit of their duties, are constantly encountering conidial 

 stages whose assignment to an order of Ascomycetes is impossible. It is an obvious 



