GEASTER. 
Exoperidium thick, divided into sections and usually recurved 
away from the inner peridium. Inner peridium sessile or stipitate with 
a single pedicel. Mouth only one. Capillitium (mostly) simple, un¬ 
branched. Spores globose, rough. We would divide the genus pri¬ 
marily into two sections. 
Rigidae (see following). 
Non-Rigidae (see page 14). 
SECTION 1. RIGIDAE. 
Exoperidium rigid, strongly incurved when dry, strongly hy¬ 
groscopic. 
This section is a very natural division of the genus readily 
recognized by the rigid incurved exoperidium segments of the dried 
specimens. All species of Geaster are hygroscopic to a more or less 
extent, but these are strongly hygroscopic. The mycelium covers the 
entire young plants and the layer is thin. When the plant expands 
the mycelium layer tears off and remains as fragments attached to the 
soil, hence the plants of this section as found in collections are smooth 
externally, and entirely devoid of mycelial layers. 
Spores large, (8-12 me.) 
Spores small, (4-6 me.) 
Mouth indeterminate, 
Mouth strongly sulcate, 
Mouth definite, even, 
(1) hygrometriens. 
(2) delicatus. 
(*) Drummondii. 
(4) mammosus. 
1. GEASTER HYGROMETRICUS. 
Unexpanded plant globose. Mycelium layer, thin, tearing away 
as the plant expands. Fibrillose layer thick, rigid, strongly hygro¬ 
scopic, splitting into six to twenty segments becoming reflexed when 
the plant is moist ; strong incurved and rigid when dry. Flesh layer 
thin, soon separating and often absent from herbarium specimens. 
Inner peridium globose, thin, opening by simply a torn aperture; col¬ 
umella none. Capillitium threads long, branched, about half diameter 
of largest spores. Spores large, globose, rough, 8-12 me. 
Pig. .5. 
Geaster hygrometricus (dried specimen.) 
8 
Fig. «. 
Geaster hygrometricus (expanded specimen.) 
