at the north. The European yew
and the curious Japanese _Gingko_ (Fig. 78, _B_) are sometimes met
with in cultivation.

Of the true conifers, there are a number of families, based on
peculiarities in the leaves and cones. Some have needle-shaped leaves
and dry cones like the firs, spruces, hemlock (Fig. 78, _C_). Others
have flattened, scale-like leaves, and more or less fleshy cones, like
the red cedar (Fig. 78, _D_) and _Arbor-vitae_ (_E_).

A few of the conifers, such as the tamarack or larch (_Larix_) and
cypress (_Taxodium_), lose their leaves in the autumn, and are not,
therefore, properly "evergreen."

The conifers include some of the most valuable as well as the largest
of trees. Their timber, especially that of some of the pines, is
particularly valuable, and the resin of some of them is also of much
commercial importance. Here belong the giant red-woods (_Sequoia_) of
California, the largest of all American trees.

The joint firs are comparatively small plants, rarely if ever reaching
the dimensions of trees. They are found in various parts of the world,
but are few in number, and not at all likely to be met with by the
ordinary student. Their flowers are rather more highly differentiated
than those of the other gymnosperms, and are said to show some
approach in structure to those of the angiosperms.

CHAPTER XV.

SPERMAPHYTES.

CLASS II.--ANGIOSPERMS.

The angiosperms include an enormous assemblage of plants, all those
ordinarily called "flowering plants" belonging here. There is almost
infinite variety shown in the form and structure of the tissues and
organs, this being particularly the case with the flowers. As already
stated, the ovules, instead of being borne on open carpels, are
enclosed in a cavity formed by a single closed carpel or several
united carpels. To the organ so formed the name "pistil" is usually
applied, and this is known as "simple" or "compound," as it is
composed of one or of two or more carpels. The leaves bearing the
pollen spores are also much modified, and form the so-called
"stamens." In addition to the spore-bearing leaves there are usually
other modified leaves surrounding them, these being often brilliantly
colored and rendering the flower very conspicuous. To these leaves
surrounding the sporophylls, the general name of "perianth" or
"perigone" is given. The perigone has a twofold purpose, serving both
to protect the sporophylls, and, at least in bright-colo