CHAPTEK XXIV 
SPERMATOPHYTES: ANGIOSPEEMS 
237. Summary of Gymnosperms. Before beginning An- 
giosperms it is well to state clearly the characters of Gym- 
nosperms which have set them apart as a distinct group of 
Spermatophytes, and which serve to contrast them with 
Angiosperms. 
(1) The microspore (pollen-grain) by wind-pollination 
is brought into contact with the megasporangium (ovule), 
and there develops the pollen-tube,, which penetrates the 
nucellus. This contact between pollen and ovule implies 
an exposed or naked ovule and hence seed, and therefore 
the name " Gymnosperm." 
(2) The female gametophyte (endosperm) is well organ- 
ized before fertilization. 
(3) The female gametophyte produces archegonia. 
238. General characters of Angiosperms. This is the great- 
est group of plants, both in numbers and importance, being 
estimated to contain about 100,000 species, and forming 
the most conspicuous part of the vegetation of the earth. 
It is essentially a modern group, replacing the Gymnosperms 
which were formerly the dominant Seed-plants, and in the 
variety of their display exceeding all other groups. The 
name of the group is suggested by the fact that the seeds 
are inclosed in a seed case, in contrast with the exposed 
seeds of the Gymnosperms. 
These are also the true flowering plants, and the ap- 
pearance of true flowers means the development of an 
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