Phylum Inophyta [ 147 



to the surface an elongate sterigma which bears a curved basidiospore. The organism 

 produces also conidia, either from the mycelium, the fruits, or directly from the 

 basidiospores. 



A series of unfamiliar other genera, Platygloca, Cystobasidium, Septobasidium, 

 etc., have been studied notably by Martin (1934, 1937, 1939, 1942). Jola and 

 Eocronartium are parasites on mosses. All of these genera produce probasidia, from 

 which four-celled phragmobasidia arise, as a layer near the surfaces of the fruits. 

 Most of them produce also conidia. 



Order 2. Hypodermia [Hypodermii] Fries Syst. Myc. 3: 460 (1832). 



Uredinees Brongniart in Bory de Saint Vincent Diet. Class. Hist. Nat. 16: 471 

 (1830). 



Order Uredineae Winter in Rabenhorst Kryptog.-Fl. Deutschland 1, Abt. 1: 

 74 (1884). 



Sub-suborder Uredinales Engler in Engler and Prantl Nat. Pflanzenfam. I Teil, 

 Abt. 1**: iii (1900). 



Order Uredinales Bessey in Univ. Nebraska Studies 7: 306 (1907). 



Order Pucciniales Clements and Shear Gen. Fung. ed. 2: 147 (1931). 

 The rusts: parasitic Basidiomycetes, the haploid and dikaryote mycelia usually 

 attacking different hosts; the dikaryote mycelium producing probasidia, these not 

 usually compacted into fruits, usually heavily walled and serving as resting spores, 

 becoming or giving rise to four-celled phragmobasidia. 



The typical reproductive structure of the haploid stage is the aecium, a cup-shaped 

 structure which releases spores called aeciospores; this stage is accordingly called the 

 aecial stage, and its host the aecial host. In addition to aecia, this stage usually pro- 

 duces pycnidia or spermagonia. The typical reproductive structures of the dikaryote 

 mycelium are clusters (telia) of spores called teliospores or teleutospores; this stage, 

 then, is the telial stage, and its host the telial host. The telial stage usually produces, 

 beside the teliospores, others called uredospores. The teliospore, or rather (since the 

 teliospore commonly consists of two or more cells) each cell of the teliospore, is a 

 probasidium, producing a promycelium which bears four basidiospores. These state- 

 ments mean that a normal rust produces spores of five kinds. Rusts producing differ- 

 ent kinds of spores were formerly supposed to be different genera; such were the 

 Aecidium, Uredo, and Puccinia of Persoon, who, however, remarked of Uredo line- 

 aris, "vereor, ne junior plantula Pucciniae graminis modo sit." De Bary first proved 

 that Aecidium Berberis is yet another stage of Puccinia graminis. 



The dikaryophase is initiated, of course, by syngamy among cells of the aecial 

 stage. In Phragmidium violaceum, Blackman observed this to take place between 

 different cells of the same hypha. Christman (1905) and Moreau (1914), studying 

 other species of Phragmidium, observed fusion to take place between tips of different 

 hyphae. Craigie, 1927, showed that Puccinia graminis occurs in two mating types, 

 and that the fertilizing elements are pycniospores or spermatia. De Bary (1884) had 

 suggested that this is the truth; his suggestion waited some forty years to be confirmed. 

 Allen (1930) has described much of the detail. The pycniospores are carried out of 

 the pycnidium in exuding fluid, and are carried by insects; they make protoplasmic 

 connection with paraphyses growing from pycnidia of the opposte mating type. The 

 binucleate uredospores arise from a dikaryote mycelium, but the cup-shaped wall of 

 the aecium is produced by the haploid mycelium. 



