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CHAPTER! XXII 



TYPES OF CRYPTOGAMS; PTERIDOPHYTES 



348. 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 1 



349. 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 w T hich 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 ? 



350. 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. 210, A}. 

 This kind of vernation (Sect. 136) is decidedly characteristic of ferns. 

 Observe the number and distribution of the roots along the rootstock. 

 Bring out all these points in a sketch. 



1 The outline here given applies exactly only to Asplenium filix-foemina. 

 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 Sedg- 

 wick and Wilson's Biology. 



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