648 THE AGARICACEAE OF MICHIGAN 



Fries used this character to subdivide the genus into three groups, 

 ,. „.. Tricholomata, with sinuate-adnexed gills; Clitocybae, with 

 gills attenuated behind and subdecurrent; Collybiae, with gills 

 equal. No examples of the Collybiae are known from the State. 

 The sinus of these three groups are normally central. With Patouil- 

 lar.l i Les. Hymen. Eur., p. 95) it seems to me desirable to include 

 here a fourth group: the Pleurdtoidae, witli eccentric or lateral 

 stem, to include the species Armillaria dryina and Armillaria corti- 

 cata. The gills are usually white but may turn yellowish or be- 

 come stained in age, depending on the species. Some species possess 

 .1 gill-trama with diverging hyphae, but in other species the hyphae 

 are parallel. The relationships shown by this character in this 

 genus are not yet very clear. The STEM is usually stout; in A. 

 bulbigera it is marginate-bulbous as in some Cartinarii. Usually 

 it is solid, and often peronate by a more or less persistent 

 sheath when young, later scaly-spotted by the breaking up 

 of this sheath. The VEIL is probably double in such species as 

 A. <-<iH<i<it<t and A. aurantia, the outer veil being continuous with 

 the cuticle of the pileus, the inner veil closely adherent to it between 

 the margin of the pileus and the underside of the young gills, it 

 is mostly membranous, but inclines to a cobwebby or flbrillose text- 

 ure in .1. bulbigera and when it sheathes the stem it breaks away 

 from the margin of the pileus to form the spreading annulus. Some- 

 times it is lacerated at the junction of cap and stem and parts of 

 it may remain on the margin of the pileus so that the pileus be- 

 comes appendiculate. In A. mellea the veil is extremely variable; 

 it is usually membranous, but sometimes fioccose-fibrillose or very 

 thin and webby so that no annulus is formed on the stem. In other 

 characters also .1. mellea is quite variable. The SPORES are white, 

 varying much in shape and size; in most species they are small 

 and almost spherical; in some, as in A. macrospora Pk. from 

 Colorado, they are elliptical and measure 10-15x6-8 micr. ' Several 

 species have a distinct ODOR; that of A. nardosmia Ell. is said to 

 resemble oil of almonds; that of A. viscidipes Pk. is strong and pene- 

 trating, somewhat alkaline. Nearly all the species are said to have 

 ,i slighl odor of some kind by which they can be distinguished. 

 A. mellea Pr. is very common and plentiful in its season; the other 

 species of Arniillaria are infrequent and can be considered rare 

 during any series of years. So far only five of the latter class 

 have been found in the State, although doubtless our northern 

 hemlock ami pine forests hide others. It has seemed best, there- 

 fore, to include in the key such species as may occur within our 



