[Vol. 2 



684 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



pargamenus as probably a synonym for P. abietinus. In that 



event, the species on the wood of deciduous trees would have 

 to be given another name. This point can be settled only by 

 a study of the type specimens of P. pargamenus, if they are 

 still preserved. Nearly all the exsiccati material has been dis- 

 tributed under the name P. pargamenus, and the plant is so 

 common and the name so well established that it is the writer's 

 opinion it should not be changed without recourse to the types. 



The two species under discussion are very closely related 

 and they are connected by intermediate forms to such an ex- 

 tent that it is difficult to refer some collections to their proper 

 species. However, the usual form of the fructification is dis- 

 tinct enough. P. abietinus is usually much smaller, is fre- 

 quently effused-reflexed with a narrow and often laterally con- 

 tinuous pileus, rarely more than 2 cm. in length, and the tubes 

 sometimes break up into lamellae-like plates — a condition I 

 have never found in P. pargamenus. That species often 

 grows much larger than P. abietinus, sometimes attaining a 

 length of 6-7 cm., and is often fan-shaped or cuneate in out- 

 line and attached by a narrow, attenuate, sometimes stem- 

 like base, so that the form and size of the fruiting body will 

 usually separate it from P. abietinus. The color, zonation, 

 and pubescence of the pileus is similar in both species, though 

 the pubescence is often inclined to be strigose in the latter 

 plant and more velvety in the former. Both species often 

 have a violaceous or lavender tint to the hymenium or on the 

 margin of the pileus. 



The microscopic appearance of the hymenium of the two 

 species does not furnish additional characters for their sepa- 

 ration. The spores are similar in size and shape, being cylin- 

 dric or sometimes allantoid, hyaline, smooth, and measuring 

 5-7 X 1.5-2.5 /x (not globose, 4.5-5.5 fi as stated by Murrill). 

 Murrill states that no cystidia are present in the hymenium of 

 P. abietinus and to the writer's knowledge their presence has 

 never been recorded. I have examined several collections of 

 both P. abietinus and P. pargamenus and I find that the plants 

 vary as regards this character. I am of the opinion that 

 cystidia are probably always present, but at times are so rare 



