486 FUNGI IMPERFECTI. 



Myxosporium. 



Conidia ovoid, hyaline, and abjointed from rod-shaped basidia 

 situated in cavities of the cortical tissues of arboreous plants ; 

 a true pycnidium is not formed, and the reproductive mycelium is 

 only covered over by the epidermal layers of the host. 



Myxosporium devastans Eostr.^ is said to attack and kill 

 young tvFigs of Betula ven-ucosa. The conidial patches are 

 developed in the killed rind, and give off unicellular colourless 

 conidia. 



M. carneum Lib. is parasitic on twigs of beech. 



M. laneola Sacc. et Ronm. causes death of oak-twigs. 



The other known species have as yet been observed only as saprophytes. 



Colletotrichum. 



Conidial patches surrounded by setae ; characters very like 

 Gloeosporium. 



Colletotrichum Lindemuthianum (Sacc. et Magn.).^ This 

 disease, first observed by Lindemuth in 1875, has assumed 

 great importance as a disease of the kidney bean {Phaseolus 

 vulgaris) both in Europe and America. Young pods are most 

 frequently attacked, but neither stems nor leaves are exempt. 

 The pods show brown depressed spots with a distinct margin. 

 The unicellular and oblong conidia are given ofi' from short 

 conidiophores developed on the spots. Germination takes place 

 at once, the germ-tube forming an adhesion-disc on the host- 

 epidermis, and from this a hypha penetrates into the tissues 

 to develop into a brown mycelium. Frank obtained brown 

 spots and mycelium on young beans twenty-four hours after 

 infection. 



C. Lagenarium (Pass.) (C oligochaetum Cav.). This parasite 

 is very injurious to seedlings of water melon {Cucumis citndlus), 

 melon (C Melo), and the gourd (Cucurbita Lagenaria). Leaves 

 and fruits may be attacked, but it is the cotyledons and stems 

 of the seedling plants which most frequently fall a prey. Spots 



' Rostrup, Tidsskriftf. Skovvaenen, 1893. 



2 For the relationship of this with the following species, as well as their 

 synoDomy, see Halsted in Bulletin of Torrey Botanical Club, 1893, p. 246. 

 Description, treatment, and bibliography by Beach, "Bean-spot disease," Genera 

 ^\ Y. BxjKr. Station Bullftin, No. 48. 



