GEASTRAE. 
We have classed the Geastraeas a sub-tribe of the Lycoperdeae, 
the essential characters of which are plants sessile, spores mixed with 
capillitium. (See “The Genera of Gastromycetes, p. 11.) 
Geastrae differ from the other Lycoperdeae in having the outer 
peridium thick, permanent, and when the plant ripens the outer peri¬ 
dium peels away from the inner, splits into segments and becomes 
more or less recurved or spreading. 
THE MYCELIUM. 
There are two distinct types of mycelium. Most Geastrae de¬ 
velop under the ground and the mycelial threads proceed from every 
portion of the outer peridium binding it to the soil. This is the usual 
type of most Geaster mycelii. In some species however, (see Fig. 57) 
the mycelium proceeds only from the base of the plant, and has the 
appearance of large cord-like roots. 
THE OUTER PERIDIUM. 
There are three distinct layers forming the outer peridium of a 
Geaster and they are quite evident to anyone who will closely observe 
them. 
1st, the mycelial or outer layer, 
2nd, the fibrillose or middle layer, 
3rd, the fleshy or inner layer, also called the Collenchyma. 
The Mycelial Layer. —This derives its name from the 
fact that in many cases in the growing plants, mycelium threads 
proceed from all parts of it and bind the plant to the surrounding 
soil. In plants of the section Rigidae it is fragile, and so closely 
attached to the soil that as the plant expands it tears away from 
the mycelial layer which remains attached to the soil. In herbar¬ 
ium specimens (see Fig. 8) of Geaster hygrometricus and others of 
the Rigidae, the outer peridium appears smooth, the mycelial layer 
having entirely disappeared. In most Geastershowever, the mycelial 
layer remains more or less firmly attached to the fibrillose but the de¬ 
gree of attachment in different specimens, otherwise the same, is of no 
importance, merely a condition. In Geaster limbatus, most of the 
specimens have the two layers adnate but we have specimens that have 
the mycelial layer only slightly attached at the extremities of the seg¬ 
ments, and specimens also where it has entirely peeled off. In some 
species, (fornicatus eoronatus, radicans in particular) the mycelial 
layer remains as a cup, the fibrillose layer separates and arches up, 
tearing away, except at the tips of the segments which remain at¬ 
tached. Species with this character are called fornicate, and as it 
seems to have been supposed to have been the character of only one 
species called fornicatus, several have been confused under this name. 
As a matter of fact quite a number of species have this character in a 
more or less perfect degree. All Geasters have an outer layer which 
9 
