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in Winter by reason of the cold. At lower altitudes this is re- 

 versed. In Winter the air is mild, rains moisten the soil, and 

 plants make their growth. In Summer the rains cease, months of 

 heat and drought ensue, and plants perish or go into a dormant 

 state for the want of moisture. 



The ferns, like the other vegetation of the region, have be- 

 come adapted in different ways to these various conditions. Most 

 of them are rupestrine, and all are so in part. Asplenium filix- 

 f amino, and Woodwardia radicans sometimes grow in mucky 

 soil around springs, and Adiantum emarginatum on grassy 

 banks, but even these more commonly prefer the addition of 

 stones or rocks to the wet soil they require. 



The ferns of the mountains are Pteris aquili?ia and its 

 variety lanuginosa, Cryptogramma achrostichoides, Pel leva 

 Wright iana compact a, Aspidium aculeatum scopulorum, Cys- 

 topteris fragilis and IVoodsia Oregana. Of these, the PelUra 

 is the only evergreen. All the rest die down to the roots in Win- 

 ter, although the variety of Aspidium aculeatum, which is a very 

 rare plant here, looks in Spring as if some of its fronds had sur- 

 vived the cold season. 



The ferns which grow at low altitudes, have their periods of 

 growth and rest regulated by the supply of moisture, and conse- 

 quently those so situated as to have an unfailing supply are able 

 to maintain a continuous growth. Such is the habit of Wood- 

 wardia radicans, which grows only where moisture is unfailing 

 and notably along streams, and of Adiantum capillus-veneris 

 which drapes the faces of shaded and dripping cliffs. Aspidium 

 munitum and A. rigidum argictum are found on stony hill-slopes, 

 in soil drier but still sufficiently moist to enable them to maintain 

 the verdure of their fronds throughout the year, although they 

 make their growth in the rainy mcnths. 



These are the only evergreen ferns of the lower altitudes, all 

 the others vegetate in Winter and become dormant in Summer, 

 thus just reversing the season of the mountain ferns. This is the 

 most numerous class, and they preserve their vitality through the 

 dry season in two different ways. Adiantum emarginatum and 

 Asplenium trichomanes incisum lose their foliage, only the root 

 persisting, thus adopting at a different season and for a different 

 cause, the habit common to so many plants of cold countries. 



But the most interesting and characteristic class have acquired 

 an adaptation, which, by enabling them to utilize to the fullest 



