180 



Mycologia 



years it has been under observation on such habitats, as it 

 appeared continuously during this period on various pots in 

 different parts of the propagating houses {fig. i). 



The most characteristic feature of the species is the appear- 

 ance of a scant mycehal growth, which gradually radiates out 

 from a common center and apparently originates from a single 

 infection. As the mycelium proceeds outward, forming con- 

 centric rings or zones, it disappears in the center, leaving a bare 

 space surrounded by the gradually enlarging rings of mycelium. 

 The perithecia later appear scattered over the mycelial growth or 

 in the central portion where the mycelium has disappeared. The 

 mycelium is very scant and never, so far as observed, gives rise 

 to a stroma, but at intervals under favorable conditions produces 

 very delicate white tufts of conidiophores bearing conidia. 

 While apparently belonging to the Verticillieae, both conidiophores 

 and conidia are very different from those of the preceding species 

 {pi. jo). The characters mentioned above would place this 

 species in the genus Nectria. A diagnosis of the species follows. 



Nectria zonata sp. nov. 



Perithecia preceded by a scant mycelial growth which radiates 

 from a common center, giving rise to concentric rings or zones, 

 finally disappearing in the center, leaving a bare space surrounded 

 by the gradually expanding rings of mycelium, with the coni- 

 diophores and conidia appearing as delicate white tufts; coni- 

 diophores verticillate-branched, with the conidia-bearing branches 

 enlarged below, gradually tapering toward the apex; conidia 

 borne in chains, fusiform, 10-12 X 5 i^^, granular within and often 

 appearing very minutely roughened; perithecia scattered, rarely 

 two together, numerous, pale-orange or flesh-red, becoming 

 slightly darker in dried specimens, under conditions of moisture 

 covered, especially near the base, with a mycelial growth giving 

 the plants a whitish appearance, or entirely naked; ostiolum 

 slightly prominent, entire or rarely collapsing in dried specimens ; 

 asci clavate, 8-spored; spores partially 2-seriate or irregularly 

 crowded, unequal-sided, broad-fusoid, i-septate, slightly con- 

 stricted at the septum, with the lower of the two cells narrower, 

 filled with numerous oil-drops, hyaline, 17-18 X S-g fi. 



Type collected in the propagating houses of the New York 

 Botanical Garden on the outside of a pot containing living plants. 

 May 20, 19 10, F. J. Seaver. 



Distribution: Known only from the type locality. 



