White : Tylostomaceae of North America 427 



dents in the districts where these plants are most common will 

 gather material in the earlier stages of growth — digging down 

 where mature forms are found above ground in the hope of find- 

 ing the young peridia. 



As far as can be ascertained, only two papers have appeared 

 treating of the growth of these plants. Schroeter * has published 

 an account of the development of the spores and basidia. Pro- 

 fessor Bessey t has a short note on the growth of T. jiianimo- 

 sum in which he says, " The ball forms underground, and reaches 

 maturity there so far as the spores are concerned. Tylostoma 

 agrees with Lycoperdon in having the interior of the ball composed 

 of two portions, first a spore-bearing part which occupies most of 

 the interior, and second a sterile base composed of tissue which 

 does not produce spores. In Tylostoma a portion of this tissue of 

 the sterile base remains living until the spores ripen. Then this 

 tissue begins a rapid growth and a cylindrical stalk is produced 

 which forces the ball through the overlying earth and carries it up 

 several inches." Massee,| speaking of Tylostoma mammosnm says, 

 " resembling a Lycoperdon with an elongated stem, but readily dis- 

 tinguished by the groove between the apex of the stem and the 

 peridium, and by the threads of the capillitium being nodulose at 

 the base of the septa." And writing of the stem, "it is some- 

 times smooth, and at others broken with small irregular fibrillose 

 squamules which are sometimes arranged more or less in circles." 



Synopsis of our Species 



Mouth entire, short tubular. 



Spores smooth, or occasionally with a few minute scattered warts. 



1. T. albicans. 

 Spores uniformly and densely verrucose. 



Peridium smooth ; capillitium not much swollen at the joints. 



2. T. pedunctilatum . 

 Peridium warty ; capillitium swollen at the joints. 3. T. verrucosum. 



Mouth lacerate-fimbriate, not tubular. 

 Spores smooth or nearly so. 

 Mouth plane. 



Stem tapering toward the base ; peridium depressed. 



4. T. gracile. 



*Cohn's Beitr. Biol. Pflan. 2 : 65. 1877. 

 fAmer. Nat. 21: 665. 1887. 

 + Ann. Bot. 4 : 85. 1S89. 



