34:6 PLANT STUDIES 
226. The plant body. The great body of the plant, 
often forming a large tree, is the sporophyte ; in fact, the 
gametophytes are not visible to ordinary observation. It 
should be remembered that the sporophyte is distinctly a 
sexless generation, and that it develops no sex organs. 
This great sporophyte body is elaborately organized for 
nutritive work, with its roots, stems, and leaves. These 
organs are very complex in structure, being made up of 
various tissue systems that are organized for special kinds 
of work. The leaves are the most variable organs, being 
differentiated into three distinct kinds : (1) foliage leaves, 
(2) scales, and (3) sporophylls. 
227. Sporophylls. The sporophylls are leaves set apart 
to produce sporangia, and in the pine they are arranged 
in a strobilus, as in the Horsetails and Club-mosses. As 
the group is heterosporous, however, there are two kinds 
of sporophylls and two kinds of strobili. One kind of 
strobilus is made up of megasporophylls bearing mega- 
sporangia ; the other is made up of microsporophylls bear- 
ing microsporangia. These strobili are often spoken of as 
the " flowers " of the pine, but if these are flowers, so are 
the strobili of Horsetails and Club-mosses. 
228. Microsporophylls. In the pines the strobilus com- 
posed of microsporophylls is comparatively small (Figs. 
308, d, 309). Each sporophyll is like a scale leaf, is nar- 
rowed at the base, and upon the lower surface are borne 
two prominent sporangia, which of course are microspo- 
rangia, and contain microspores (Fig. 309). 
These structures of Seed-plants all received names 
before they were identified with the corresponding struc- 
tures of the lower groups. The microsporophyll was called a 
stamen, the microsporangia pollen-sacs, and the microspores 
pollen-grains, or simply pollen. These names are still very 
convenient to use in connection with the Spermatophytes, 
but it should be remembered that they are simply other 
names for structures found in the lower groups. 
