THE FUNGI WHICH CAUSE PLANT DISEASE 167 



Conidia borne on distinct conidio- 

 phores 

 Conidia bome singly; conidio- 

 phores branching at right 



angles 6. Aphanoascus. 



Conidia bome in chains 

 Conidiophores simple, aggre- 



, gated into btmdles 7. Emericella. 



Conidiophores enlarged apically 

 bearing numerous sterig- 

 mata 



Sterigmata simple 8. Aspergillus, p. 168. 



Sterigmata branched 9. Sterigmatocystis. 



Conidiophores, sympodially 



branched 10. Eurotiopsis. 



Conidiophores bushy branched 

 Conidiophores single, peri- 



thecia sessile 11. Penicilliuin, p. 169. 



Conidiophores in bundles, api- 

 cal cells swollen, peri- 



thecia stalked 12. Penicilliopsis. 



Spores 2-ceUed; peridium at maturity stel- 

 late 13. Testudina. 



Of the thirteen genera and some one hundred to two hundred 

 species only four of the genera are of interest here. The others 

 occur on rotting leaves, maniu-e, etc. 



Thielavia Zopf '^'* (p. 166) 



T. basicola (B. and Br.) Zopf. 



This, the one species of the genus, is on the boundary between 

 the Aspergillales and the Perisporiales and is classed by some with 

 the one, by some with the other order. 



The ascocarps, which are the form less commonly seen, are 

 round, brown, completely closed and have no appendages. The 

 asexual spores are of two kinds. First: hyaline conidia produced 

 endogenously within "pistol-formed" conidiophores from the 

 ends of which they are expelled. Second: short cylindrical conidia 

 or chlamydospores with a thick brown wall; bome in series of 



