722 THE AGARICACEAE OF MICHIGAN 



white tomentum, often ferruginous-stained, white or whitish, bulb 

 at length color of pileus. SPORES elliptic-oval. 7-7.5 x 5-5.5 micr., 

 obscurely echinulate, nucleate, white. CYSTIDIA none; sterile 

 cells on edge of gills acicular. ODOR rather strong, oily-farinace- 

 ous. TASTE mild. 



Gregarious or subcaespitose. On the ground in frondose woods. 

 Ann Arbor, Detroit. August-September. Infrequent. 



In America this huge and massive mushroom is distinguished 

 by its exceedingly stout stem, by the compact flesh of the half -grown 

 plant, by the gills which soon become deep straw-yellow and by 

 the odor. When developing slowly the pileus remains compact 

 and thick on the central portion, but under favorable growth-con- 

 ditions it expands more fully, the flesh becomes thinner through- 

 out and it tends to become infundibuliform. The majority of 

 plants found, although many of them very large, had a plane or 

 obtuse pileus, sometimes with a very broad umbo. Solitary, rela- 

 tively small specimens approach the appearance of the figures given 

 for C. geotropa Fr. and such specimens being the only ones seen the 

 first time the species was found, I referred them to C. geotropa Fr. ; 

 later collections showed me the error. The gills in the young plants 

 are merely sinuate-emarginate, but when the pileus expands they 

 become decurrent. The decurrent character of the gills is not as 

 strongly marked as the European descriptions indicate, and our 

 plant departs from European forms in several particulars. Fries 

 (Monographia) says the gills are whitish, not changing, whereas 

 the yellowish to tan color which the gills soon assume 

 in our plants is one of the most marked characteristics, 

 becoming more noticeable after the specimens are picked. 

 The thin tomentose coating on the stem, its bulbous 

 tendency and the rusty-tan color of the old plants is 

 also not mentioned. Clearly we have a distinct American form. 

 The relation between C. maxima and C. gigantea does not seem to 

 be clear to most European authors. The two are very distinct as 

 Fries has pointed out. The American C. gigantea has a whitish, 

 ill inner, much more infundibuliform pileus and its gills are more 

 crowded and anastomose on the stem, and the margin of the pileus 

 is strongly marked by sulcate-ridges. The attachment of the gills 

 relates this to the genus Tricholoma. But in all other respects it 

 is a Clitocybe of the Paxilloideae group. 



