s cone with its
intermittent seed-release, and the multinodal spring-shoot. There are,
moreover, new forms of leaf-hypoderm and a new position of the
resin-duct.

Of these new characters, the thick wing-blade attains such proportions
in the three species of the Macrocarpae that they can be grouped
apart. But the characters that finally culminate in a lateral oblique
serotinous cone are so gradually and irregularly developed that they
offer no divisional distinctions. With the aid of wood and leaf
characters, however, groups can be established which preserve the
evolutionary sequence and, at the same time, the obvious affinity of
the species.

Wing-blade thin or slightly thickened at the base.
Cones dehiscent at maturity.
Pits of the ray-cells large X. Lariciones
Pits of the ray-cells small XI. Australes
Cones serotinous, pits of the ray-cells small XII. Insignes
Wing-blade very thick XIII. Macrocarpae

The species of this subsection are very difficult, if not impossible,
to classify by the usual method, which groups all species under a few
characters assumed to be invariable and of fundamental importance.
Such a method can be successfully applied to the Soft Pines and to
some of the Hard Pines, but cannot be applied to all the Hard Pines
without forcing some of them into unnatural associations.

To take an example, the group Pseudostrobus, characterized by
pentamerous leaf-fascicles, appears in many systems. In this group are
placed P. Torreyana and P. leiophylla. Another group, with trimerous
fascicles, contains P. Sabiniana and P. taeda. Now there are no two
species more obviously related by important peculiarities than P.
Torreyana and P. Sabiniana; nevertheless they are, by this method,
kept apart and associated with species which they resemble in no
important particular.

An attempt is made here to avoid such incongruities. Groups X, XI and
XII represent different stages of evolution. In the Lariciones the
cone is symmetrical, and dehiscent and deciduous at maturity, while
the spring-shoot is uninodal. In the Australes there is a similar
cone, but the spring-shoot gradually becomes multinodal. In the
Insignes the cone is oblique, persistent and serotinous, and the
spring-shoot is multinodal.

These definitions state the degree of evo