CHARLES THOM 511 



The first Aspergillus to become well known to botanists was found by the collec- 

 tors upon partly dried and even mounted specimens in the herbarium. The large 

 heads of gray-green spores were conspicuous wherever the botanist turned his hand 



ARTIFICIAL KEY TO GROUPS — PRIMARILY BASED ON COLOR 



A. Conidial heads green or yellow green B 



AA. Conidial heads never green I 



B. Stalks smooth C 



BB. Stalks pitted (often rough as seen with low magnification) H 



C. Vesicle cylindrical clavate, stalks coarse A. clavatus 



CC. Vesicle flask-shaped or globose, not cylindrical clavate .... D- 



D. Sterigmata in i series E 



DD. Sterigmata in 2 series F 



E. Conidia mostly elliptical and more than 4 ju in long axis. 



Perithecia commonly found, yellow A. glauciis group 



EE. Conidia mostly globose 4 /x or less in long axis; conidial 



chains in narrow, solid columns A. Jumigatus group 



F. Conidial chains in columns A. nidulans 



FF. Conidial chains in radiate heads G 



G. Heads blue green A. sydowi 



GG. Heads glaucus, green, or yellow green to buff A. versicolor 



H. Stalks pitted (often appearing to be rough or asperulate 



with low magnifications) A. flavus-oryzae group 



I. Conidial heads never green J 



J. Stalks smooth K 



JJ. Stalks pitted (or apparently rough) O 



K. Conidial heads avellaneous or in brown shades L 



KK. Conidial heads white (or slightly yellowed in age) N 



KKK. Conidial heads brown to black '. . . . A. niger group 



KKKK. Conidial heads orange to umber A. wentii 



L. Conidial heads in columns M 



LL. Conidial heads radiate, stalks colored A. uslus 



M. Stalks colorless or nearly so A. terreiis 



MM. Stalks yellowed (especially in outer layer) A.flavipes group 



N. Stalks yellowed, conidial chains in columns A.flavipes group 



NN. Stalks colorless; heads mostly radiate or globose A. candidus group 



O. Stalks pitted or rough P 



P. Heads yellow to ochre, radiate Q 



Q. Heads in bright-yellow colors A. siilphureus 



QQ. Heads in ochraceous shades A. ochraceiis group 



PP. Heads orange to umber; conidia rough with tubercles and 



bars of color A. tamarii and allies 



lens. Hence they were called Aspergillus daucus, while the yellow perithecia scat- 

 tered over the same areas were long supposed to be a separate fungus which was called 

 Eurotium herbarioriim. Only in comparatively recent times have we come to know 

 that there are many species and races with this general morphology; that they are 

 able to maintain themselves more successfully in places of physiological drought than 

 the other common and conspicuous molds. We thus find them as piled masses of red, 



