Houc: pi£zizALi-:s, phacidiaf.es and tuberales of MINN. 119 



2. Tuber lyoni Butters. Bot. Gaz. 35:427-431. 1903. (Plate XIV. Fig. 

 5.) 



Ascomata globose or irregularly elliptical, 0.5-2 cm. in diameter, 

 having a distinct scar-like groove along one side, smooth, light 

 chestnut-brown, becoming finally very minutely areolate and black- 

 ish ; peridium not thick, cartilaginous ; gleba violaceous brown, 

 fleshy but somewhat granular ; septae arising from the peridium 

 nimierous, anastomosing", labyrinthiform, dark translucent; venae ex- 

 ternae white, conspicuous, opening externally throughout the length 

 of the groove; asci pedicellate, 1-5 mostly 4 spored ; spores elliptical, 

 acutely echinulate, 15-31 x 25-48 mic. 



(i) Beneath Tilia amcricana in calcareous clay soil covered 

 with leaf-mold, on a steep bank of southern exposure. (2) In leaf- 

 mold on island in Lake Minnetonka. Hennepin, March 1903, Lyon 

 & Butters 205 ; Hennepin, Sept. 1903, Kelson. 



The above description is taken from Prof. Butters' description 

 (2, p. 431)- The type specimens are deposited in the Herbarium 

 of the University of Minnesota, in both the dried condition and in 

 2 per cent formalin. The plant is closely related to Tuber nitidum 

 Vittad. and Tuber ritfum Pico. 



Explanation of Plates. 



All photographs are natural size. 



Plate XIV. 

 Figure i. Sclerotinia tuberosa (Hedw.) Fries, with sclerotium 



exposed. 

 Figure 2. Chlorosplenium aeruginascens (Nyl.) Karst. 

 Figure 3. Lachnea hemisphaerica (Wigg.) Gill. 

 Figure 4. Macropodium macropus (Pers.) Fckl. 

 Figure 5. Tuber lyoni Butters. 

 Figure 6. Helotium citrinum (Hedw.) Fries. 



Plate XV. 

 Plicaria repanda (Wahlenbg.) Rehm. 



Plate XVI. 

 Urnula craterium (Schw.) Fries. 



Plate XVII. 

 Figure i. Sclerotinia tuberosa (Hedw.) Fries; photographed in 



the field. 

 Figure 2. Discina venosa reticulata (Grev.) Rehm. 



Plate XVIII. 

 Sarcoscypha coccinea (Jacq.) Cooke. 



