Riddle: Observations on Acrospermum 177 



to as a stipe ; while in the specimens distributed in Libert Plantae 

 Cryptogamicae Arduennae No. 32 and in the Kryptogamae Exsic- 

 y catae Vindobonenses No. 1435, there is a well-defined stipe, cylin- 

 drical and of considerable relative length (Fig. 10). The surface 

 varies from even (Fig. 7) to wrinkled (Fig. 8), and longitudinally 

 furrowed (Fig. 10). The color is typically bay-brown, 3 but varies 

 to seal-brown, snuff-brown, and russet; rarely {e.g., Berkeley's 

 British Fungi Exsiccati No. 270) it may be dull fuscous-black. 

 The color of any given perithecium is usually fairly uniform 

 throughout, but occasional specimens are seen {e.g., Mougeot and 

 Nestler Stirpes Cryptogamae Vogeso-Rhenanae No. 671), where 

 the color becomes gradually paler toward the apex. 



Connecting with the typical form of the species and distinguish- 

 able only as varieties are two plants which have been described as 

 distinct species. The first of these is Acrospermum graminum 

 Libert, usually smaller than A. compressum, somewhat darker in 

 color, with a linear outline, and growing on dead leaves of grasses 

 (Fig. 5). Rehm has already reduced this to varietal rank. 



The second plant is Acrospermum foliicolum Berk. Authentic 

 specimens in the Curtis Herbarium show that in size and in shape, 

 Figs. 9 and 10 would represent this plant as well as the typical 

 form of A. compressum. The color of A. foliicolum is in general 

 lighter than that of A. compressum, being from honey-yellow to 

 russet. But it will be noticed that darker specimens of the former 

 coincide in color with lighter specimens of the latter. The only 

 constant difference that the writer has been able to discover be- 

 tween the two forms is the habitat: all specimens of A. compres- 

 sum that have been seen grow on stems, while all the specimens of 

 A. foliicolum grow on Dicotyledonous leaves. This would scarcely 

 seem to be of sufficient importance to maintain a specific difference 

 between the two. 



The variations of Acrospermum compressum may be summar- 

 ized as follows : 



Acrospermum compressum Tode Fungi Mecklenb. 1 : 8, t. 2, f. 

 13. 1790. 



3 All color terms in this paper are taken from Ridgeway : Color Standards 

 and Nomenclature. 19 12. 



