CHYTRIDIALES 475 



PHYSOCLADIA Sparrow 



Mycologia, 24: 285. 1932 

 (Fig. 30 A, p. 474) 



Thallus predominantly extramatrical, rhizoidal, much branched, poly- 

 centric, with septate turbinate cells and nonseptate fusiform or irregular 

 swellings, bearing the rudiments of the sporangia and resting spores ; 

 sporangia inoperculate, terminal, proliferating; zoospores posteriorly 

 uniflagellate, with a single globule, produced within the sporangium, 

 liberated through a pore formed upon the deliquescence of a papilla 

 and undergoing a period of swarming in a vesicle at the orifice before 

 escaping; resting spores thick-walled, borne on the thallus, germination 

 not observed. 



Known thus far only as a saprophyte of the staminate cones of Pinus. 



This monotypic genus resembles Nowakowskiella very closely. It 

 differs in having an inoperculate sporangium which forms a well-defined 

 vesicle within which, upon discharge, the zoospores swarm before their 

 escape. 



Physocladia obscura Sparrow 

 Mycologia, 24: 285, fig. 4e. 1932 



(?) Nowakowskiella obscura Sparrow, Amer. J. Bot., 18: 621, pi. 45, figs. 

 A-G. 1931. 



Sporangia terminal, spherical or subspherical, apophysate, 42 u. in 



B, habit of plant bearing single sporangium; C, single zoospore with pale- 

 yellow globule; D, empty sporangium with long discharge tube; E, partly 

 discharged sporangium; remaining contents and globules are pale yellow. 

 F-G. Amoebochytrium rhizidioides Zopf in slime sheath of Chaetophora: F, 

 mature apophysate sporangium with globules of spores; septum in discharge 

 tube is still present ; G, some of shapes assumed by nonflagellated amoeboid 

 spores. H. Polychytrium aggregation Ajello, portion of thallus showing 

 smooth- and rough-walled (tuberculate) zoosporangia and discharge of zoo- 

 spores. /. Cladochytrium tenue Nowakowski in decaying tissue of Acorns 

 calamus. 



(A, Sparrow, 1931c; B-E, Deckenbach, 1902-3; F-G, Zopf, 1884; H, 

 Ajello, 1942; I, Sparrow, 1943) 



