3.--Paxillus panuoides, pale yellow;
natural size. Copyright.]

[Illustration: PLATE 55.

FIG. 1.--Boletus felleus.
FIG. 2.--B. edulis.
Copyright 1900.]

CHAPTER IX.

THE TUBE-BEARING FUNGI. POLYPORACEAE.

The plants belonging to this family are characterized especially by a
honey-combed fruiting surface, that is, the under surface of the plants
possesses numerous tubes or pores which stand close together side by
side, and except in a very few forms these tubes are joined by their
sides to each other. In _Fistulina_ the tubes are free from each other
though standing closely side by side. In _Merulius_ distinct tubes are
not present, but the surface is more or less irregularly pitted, the
pits being separated from each other by folds which anastomose, forming
a network. These pits correspond to shallow tubes.

The plants vary greatly in consistency, some are very fleshy and soft
and putrify readily. Others are soft when young and become firmer as
they age, and some are quite hard and woody. Many of the latter are
perennial and live for several or many years, adding a new layer in
growth each year. The larger number of the species grow on wood, but
some grow on the ground; especially in the genus _Boletus_, which has
many species, the majority grow on the ground. Some of the plants have a
cap and stem, in others the stem is absent and the cap attached to the
tree or log, etc., forms a shelf, or the plant may be thin and spread
over the surface of the wood in a thin patch.

In the genus _Daedalea_ the tubes become more or less elongated
horizontally and thus approach the form of the gills, while in some
species the tubes are more or less toothed or split and approach the
spine-bearing fungi at least in appearance of the fruit-bearing surface.
Only a few of the genera and species will be described.

The following key is not complete, but may aid in separating some of the
larger plants:

Tubes or pores free from each other, though
standing closely side by side, _Fistulina_.
Tubes or pores not free, joined side by side, 1.
1--Plants soft and fleshy, soon decaying, 2.
Plants soft when young, becoming firm, some
woody or corky, stipitate, shelving, or spread
over the wood, _Polyporus_.
Tubes or pores shallow, formed by a network of
folds or wrinkles, plants thin, sometimes spread