292 INTRODUCTION TO BOTANY 
277. Seed formation. The odspore that is formed by the 
union of the sperm and the egg grows and becomes the em- 
bryo of a new pine plant. The tissues that surround this 
developing embryo are partly absorbed by it and used in 
nourishing it. By the time the embryo has developed root tip, 
stem tip, and young leaves, the walls of the ovule have begun 
to harden, and the whole structure is recognized as the seed 
(fig. 226). When the pine cone opens, usually two years or 
more from the time when pollination occurred, the seeds fall 
to the ground and, if conditions are favorable, begin to ger- 
minate. In germination the embryo 
swells and bursts the seed coat, the 
root grows downward into the soil, 
and the leaves rise into the air; in 
time the embryo becomes a new tree, 
Fie. 226. Diagram of the seed which may bear cones and repeat 
of a pine, showing the embryo the process of reproduction. 
(new pine plant) Inclosed within «= §- The cones may not shed thei 
the food material : 
AViecieniittp ortits ammegals seeds for several years (as in the 
the root, and at the left are the case of the lodgepole pine of the 
Sood leaves scltieh inolose The Rocky Rountams), or not ever 
small stem tip f 
until the death of the tree, and the 
young plants within the seeds may still remain alive and ready 
to grow when properly placed for germination. It is becom- 
ing a common practice of forestry to collect pine seeds in great 
quantities and sow them over thousands of acres, thus resetting 
or extending the areas in which pine seedlings grow. 
278. Other gymnosperms. There are several groups of gym- 
nosperms, but the one to which the pines belong (the conifers) 
is the only one that need be mentioned here. The conifers take 
their name from the cone-bearing habit which is characteristic 
of all members of the group. In addition to the widely dis- 
tributed genus (Pinus) already discussed, other important 
representatives of the conifers are the spruces (Picer), which 
have stubby needle leaves (fig. 227, .fand B), close-set branches, 
and pendent cones; the Western hemlock, the Douglas fir 
