CHAPTER XVII 
PTERIDOPHYTES (FERN PLANTS) 
General Discussion. — Ferns are much larger plants than 
Bryophytes and consequently are much better known by the 
general public. In the woods Ferns are common and often they 
can be found in the fields. On account of their large, attractive, 
feather-like leaves, they are common house plants and are ex- 
tensively grown in greenhouses. Most Ferns require a moist or 
shady region, but some are able to grow in dry situations. 
In studying the different layers of rock which form the earth’s 
crust, many Pteridophytes are found preserved. In the layer 
of rock from which coal is obtained, Pteridophyte fossils are very 
abundant. These fossils show that Pteridophytes were at one 
time much more abundant than now. Some of these ancient 
forms were like trees in size and resembled Seed Plants more than 
any of the present forms do. Although the forms that made 
most advancement toward Seed Plants have long been extinct, 
the forms which now exist show us some of the lines along which 
progress was made. 
In beginning the study of Pteridophytes, one should have in 
mind the features contributed by the Bryophytes, because the 
Pteridophytes are supposed to have come from forms like the 
Bryophytes, although we are not able to connect them up with 
any of the existing forms of Bryophytes. From forms like the 
Bryophytes, the Pteridophytes inherited the land-habit. They 
not only inherited those features which enable plants to live, 
work, and reproduce in the air, but they have improved upon 
these features, so that in general they are better fitted to live on 
land than most of the Bryophytes. They have the alternation 
of generation ‘which the Bryophytes so firmly established and 
have carried the sterilization of sporogenous tissue so far that the 
sporophyte is a massive and well differentiated plant body. 
Probably, instead of speaking of it as sterilization of sporogenous 
tissue, it would be clearer to say that the fertilized egg now pro- 
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