CHAPTER XXV 
TYPES OF CRYPTOGAMS ; PTERIDOPHYTES 
311. The Group Pteridophytes.— Under this head are 
classed the ferns, the scouring-rushes, and the club-mosses. 
They are the most highly organized of cryptogams, having 
true roots, and often well-developed stems and leaves. 
THE STUDY OF A FERN} 
312. Conditions of Growth. — If the specimens studied were col- 
lected by the class, the collectors should report exactly in regard to 
the soil and exposure in which the plants were found growing. Do 
any ferns occur in surroundings decidedly different from these ? 
What kind of treatment do ferns need in house culture? 
313. The Underground Portion. — Dig up the entire underground 
portion of a plant of ladyfern. Note the color, size, shape, and- 
appendages of the rootstock. If any are at hand which were col- 
lected in their late winter or early spring condition, examine into 
the way in which the leafy parts of the coming season originate 
from the rootstock, and note their peculiar shape (Fig. 171, 4). 
1 The outline here given applies exactly only to Asplenium filix-femina. 
Any species of Asplenium or of Aspidium is just as well adapted for study. 
Cystopteris is excellent, but the indusium is hard to find. Polypodium vul- 
gare is a simple and generally accessible form, but has no indusium. Pteris 
aquilina is of world-wide distribution, but differs in habit from most of our 
ferns. The teacher who wishes to go into detail in regard to the gross anat- 
omy or the histology of ferns as exemplified in Pteris will find a careful 
study of it in Huxley and Martin’s Biology, or a fully illustrated account in 
Sedgwick and Wilson’s Biology. 
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