1920] 
BURT—THELEPHORACEAE OF NORTH AMERICA. XII 191 
even, 10-13X32-41 u; colored 
spores 12X3j-4 , sometimes | 
occur in deeper zones of the 
hymenium. | 
Resupinate part 1-8 cm. long, i 
1-4 cm. wide, reflexed part 1-5 
mm. broad in the only reflexed 
specimen known. 
On logs of Abies and, perhaps, | MA 
Pinus Strobus. Vermont and Il 
New York. June to November. 
Very rare. j ; 
S. ambiguum belongs in the FE 30 S ortiga. Section of 
group of species with S. abietinum of cystidium, c, and spores, s, X 650. 
and S. rugisporum on account 
of similarity in microscopic structure including the colored 
cystidia. It may be separated from both these species at sight 
by the color of its hymenium which is permanently umber and 
not at all cinereous nor glaucous. There is a difference in 
chemical composition also, for dilute potassic hydrate solution 
blackens the sections and becomes itself discolored as in the 
case of species of Hymenochaete. In fact, the general aspect 
of resupinate, thick, mature, deeply cracked specimens is very 
like that of Hymenochaete spreta—a species which occurs only 
exceptionally on a coniferous substratum. It is possible that 
S. ambiguum occurs in reflexed form in the state of Washing- 
ton, for the collection cited under S. rugisporum, Olympie 
Mts., T. C. Frye, 1, resembles S. ambiguum but is not quite in 
perfect enough conden’ for confident reference here. 
Specimens examined: 
Vermont: Middlebury, C. G. Lloyd, 10652 (in Lloyd Herb. and 
Mo. Bot. Gard. Herb., 44585); Ripton, E. A. Burt; Smug- 
glers Notch, Mt. Mansfield, E. A. Burt. 
New York: Adirondack Mts., C. H. Peck, type (in N. Y. State 
Mus. Herb.); Averyville, C. H. Peck (in N. Y. State Mus. 
Herb. and Mo. Bot. Gard. Herb., 55699). 
~T 
- L— 
— 
- = ——— 
GÀ 
"-—— 
I 
Im 
== == 
—M — 
A 
m i : 
59. S. umbrinum Berk. & Curtis, Grevillea 1: 164. 1873; 
Wakefield, Kew Bul.1915:369. 1915.—Compare Stereum umbri- 
