THE GENUS LASIOSPHAERIA 



Fred J. Seaver 

 (With Plates 66 and 67, Containing 37 Figures) 



In working over the Trichosphaeriaceae preparatory to a mono- 

 graph of the family a number of points of interest have arisen 

 relating both to genera and species. In order to bring out some 

 of these points the North American species of the genus Lasio- 

 sphaeria are here described and illustrated. 



The genus Lasiosphaeria was founded in 1863 by Cesati and 

 De-Notaris, with Sphaeria ovina Pers. as type of the genus. In 

 1869 Fuckel took up the genus Leptospora Rabenh. but used it 

 in a different sense from that in which it was originally used by 

 Rabenhorst/ including Sphaeria ovina Pers. in this genus. In 

 the diagnosis of the genus Leptospora Fuckel states : " Diese 

 Gattung steht, was den Sporenbau anbelangt, Lasiosphaeria 

 nahe, nur sind bei Leptospora die Sporen ohne Querwanden." 

 In the members of this group of plants it is very difficult to rely 

 upon the septation of the spores as a basis for generic distinc- 

 tion since in many species the spores are nonseptate when young 

 and it is difficult to find mature spores, but when mature spores 

 are found, they are often delicately separate. The type of the 

 genus Lasiosphaeria as usually collected has nonseptate vermi- 

 form spores while rarely plants of the same species are found with 

 some of the spores enlarged at one end into an ellipsoid head and 

 becoming one or more septate. Other species of the genus which 

 usually contain nonseptate spores occasionally have the spores 

 septate without enlargement, the number of septa varying with 

 the species. While Fuckel in his diagnosis of the genus Lepto- 

 spora regards the spores as nonseptate he includes in the genus 

 species in which, as described above, the spores are often septate. 

 The genus Leptospora of Fuckel is therefore regarded as a 

 synonym of Lasiosphaeria, in which genus the presence or 

 absence of septa is a variable character. 



^ Hedwigia I : 116. 1857. 



115 



