ch
marks the members of this family is the peculiarity of the fruiting
surface, just as a number of the other families are distinguished by
some peculiarity of the fruiting surface. In the _Hydnaceae_ it covers
the surface of numerous processes in the form of spines, teeth, warts,
coarse granules, or folds which are interrupted at short intervals.
These spines or teeth always are directed toward the earth when the
plant is in the position in which it grew. In this way the members of
the family can be distinguished from certain members of the club fungi
belonging to the family _Clavariaceae_, for in the latter the branches or
free parts of the plant are erect.

In form the _Hydnaceae_ are shelving, growing on trees; or growing on the
ground they often have a central or eccentric stem, and a more or less
circular cap; some of them are rounded masses, growing from trees, with
very long spines extending downward; others have ascending branches from
which the spines depend; and still others form thin sheets which are
spread over the surface of logs and sticks, the spines hanging down from
the surface, or roughened with granules or warts, or interrupted folds
(see _Phlebia_, Figs. 193, 194). In one genus there is no fruit body,
but the spines themselves extend downward from the rotten wood, the
genus _Mucronella_. This is only distinguished, so far as its family
position is concerned, from such a species as _Clavaria mucida_ by the
fact that the plant grows downward from the wood, while in _C. mucida_
it grows erect.

HYDNUM Linn.

The only species of the _Hydnaceae_ described here are in the genus
_Hydnum_. In this genus the fruiting surface is on spine, or awl-shaped
processes, which are either simple or in some cases the tips are more or
less branched. The plants grow on the ground or on wood. The species
vary greatly in form. Some are provided with a more or less regular cap
and a stem, while others are shelving or bracket shaped, and still
others are spread out over the surface of the wood (resupinate).

[Illustration: FIGURE 195.--Hydnum coralloides. Entirely white (natural
size). Copyright.]

=Hydnum coralloides= Scop. =Edible.=--Among the very beautiful species
of the genus _Hydnum_ is the coral one, _Hydnum coralloides_. It grows
in woods forming large, beautiful, pure white tufts on rotten logs,
branches, etc. The appearance of one of these tufts is shown in Fig.
195. There is a common stem which arises from