Figs. 346-350.—White pine showing details of mature scales and seed.
Fig. 351.
Female cones of the pine at time
of pollination, about natural size.
614. Formation of the female pine cone.—The female flowers begin their development rather late in the spring of the year. They are formed from terminal buds of the higher branches of the tree. In this way the cone may terminate the main shoot of a branch, or of the lateral shoots in a whorl. After growth has proceeded for some time in the spring, the terminal portion begins to assume the appearance of a young female cone or flower. These young female cones, at about the time that the pollen is escaping from the anthers, are long ovate, measuring about 6-10 mm long. They stand upright as shown in [fig. 351].
615. Form of a “scale” of the female flower.—If we remove one of the scales from the cone at this stage we can better study it in detail. It is flattened, and oval in outline, with a stout “rib,” if it may be so called, running through the middle line and terminating in a point. The scale is in two parts as shown in [fig. 354], which is a view of the under side. The small “outgrowth” which appears as an appendage is the cover scale, for while it is smaller in the pine than the other portion, in some of the relatives of the pine it is larger than its mate, and being on the outside, covers it. (The inner scale is sometimes called the ovuliferous scale, because it bears the ovules.)
Fig. 352.
Section of female cone
of white pine, showing
young ovules
(macrosporangia)
at base of the
ovuliferous scales.
Fig. 353.
Scale of white pine
with the two ovules
at base of
ovuliferous scale.
