418 THE FUNGI WHICH CAUSE PLANT DISEASE 



Merulius lachrymans of the tribe Merulieae is said to parasitize 

 violets. 



Poria Persoon (p. 417) 



Sporophore entirely resupinate, often widely extended, the 

 base leathery to punky, pores small, rounded, covering almost the 

 entire surface. 



A genus of almost three hundred species. 



P. laevigata Fr. causes a white rot of the birch. 



P. vaporaria (Pers.) Fr. is a woimd parasite on coniferous trees ^* 

 especially common on spruce and fir causing a brown rot of the sap 

 wood. 



P. subacida Pers.^* Sporophore effused, determinate; margin 

 pubescent, white; pores minute, subrotund, 2-6 mm. oblique, 

 odor subacrid. A common saprophyte on deciduous and conif- 

 erous trees especially, pine, hemlock, and spruce. Irregular 

 cavities form within the diseased wood and become lined with a 

 tough felt of hyphae, yellow on the inner side. 



P. hypolaterita Berk, causes a tea disease in Ceylon.^^ 



P. vineta Berk, is reported as causing a rot of Hevea in Ceylon.'* 



Polyporus (Micheli) Paulet (p. 417) 



Sporophore usually annual; simple or compound, rather thick, 

 fleshy, leathery or corky, stipitate or shelving, pores developing 

 from the base toward the margin. Grading into Polystictus on 

 the one hand and approaching Fomes on the other. 



There are about five himdred species. 



P. obtusus Berk.«'' " 



Pileus somewhat imbricate, large and spongy, at length indurate, 

 dimidiate, sessile, often ungulate, 5-7 x 10-15 x 3-5 cm.; surface 

 spongy-tomentose, hirtose, azonate, smooth, sordid-white to 

 isabelline or fulvous; margin very thick and rounded, sterile, 

 entire, concolorous; context spongy-fibrous, white, indurate with 

 age especially below, 1-2 cm. thick; tubes very long, 2-3 cm., 

 white to isabelline within, mouths large, irregular, often sinuous, 

 1-2 mm. broad, edges thin, fimbriate-dentate to slightly lacerate, 

 white to isal3elline, at length bay and resinous in appearance; spores 

 globose, smooth, hyaline, &-8 n; hyphse hyaline, 6 m; cystidia none. 



