) are
nearly triangular in shape, and attached by the smaller end. On the
lower side of each are borne two sporangia (pollen sacs) (_C_, _sp._),
opening by a longitudinal slit, and filled with innumerable yellow
microspores (pollen spores), which fall out as a shower of yellow dust
if the branch is shaken.

The macrosporangia (ovules) are borne on similar leaves, known as
carpels, and, like the pollen sacs, borne in pairs, but on the upper
side of the sporophyll instead of the lower. The female flowers appear
when the pollen is ripe. The leaves of which they are composed are
thicker than those of the male flowers, and of a pinkish color. At the
base on the upper side are borne the two ovules (macrosporangia)
(Fig. 77, _E_, _o_), and running through the centre is a ridge that
ends in a little spine or point.

The ovule-bearing leaf has on the back a scale with fringed edge (_F_,
_sc._), quite conspicuous when the flower is young, but scarcely to be
detected in the older cone. From the female flower is developed the
cone (Fig. 75, _A_), but the process is a slow one, occupying two
years. Shortly after the pollen is shed, the female flowers, which are
at first upright, bend downward, and assume a brownish color, growing
considerably in size for a short time, and then ceasing to grow for
several months.

[Illustration: FIG. 75.--Scotch pine (_Pinus sylvestris_). _A_, a ripe
cone, x 1/2. _B_, a year-old cone, x 1. _C_, longitudinal section of
_B_. _D_, a single scale of _B_, showing the sporangia (ovules) (_o_),
x 2. _E_, a scale from a ripe cone, with the seeds (_s_), x 1/2. _F_,
longitudinal section of a ripe seed, x 3. _em._ the embryo. _G_, a
germinating seed, x 2. _r_, the primary root. _H_, longitudinal
section through _G_, showing the first leaves of the young plant still
surrounded by the endosperm, x 4. _I_, an older plant with the leaves
(_l_) withdrawing from the seed coats, x 4. _J_, upper part of a young
plant, showing the circle of primary leaves (cotyledons), x 1. _K_,
section of the same, x 2. _b_, the terminal bud. _L_, cross-section of
the stem of the young plant, x 25. _fb._ a fibro-vascular bundle. _M_,
cross-section of the root, x 25. _x_, wood. _ph._ bast, of the
fibro-vascular bundle.]

In Figure 75, _B_, is shown such a flower as it appears in the winter
and early spring following. The leaves are thick and fleshy, closely
pressed together, as is seen by dividing the flower lengthwise, and
each l