INFLUENCE OF ENVIRONMENT 273 



bay. The protective character of the strong odors 

 found in many plants of the same regions has also been 

 referred to. 



Where a region is subjected to well-marked wet and 

 dry seasons, there are always a great many plants which 

 pass the dry season in a dormant condition, very much 

 as similar plants hibernate during the cold season of 

 more northern regions. These plants generally develop 

 bulbs or tubers, which may be completely dried up 

 without injur}'. Bulbous plants are especially abun- 

 dant in such semi-arid regions as central and southern 

 California, the Cape of Good Hope, and the shores of 

 the Mediterranean, where many bulbous Monocotyle- 

 dons occur, among them some of the choicest garden 

 flowers, like the various species of Narcissus, Iris, 

 Gladiolus, etc. 



While these special adaptations to resisting dryness 

 are particularly well developed in the flowering plants, 

 there are also many striking examples among the lower 

 plants, especially among Pteridophytes and Bryophytes. 

 In California many ferns become completely dried up 

 during the long rainless summer, but some of them, 

 like the gold-back fern (^Crymnogramme triangularis), 

 on being placed in water will revive immediately, the 

 dried-up leaves unfolding and becoming fresh and 

 green. The curious "resurrection plant," from the 

 southern part of the state, is one of the club-mosses 

 {Selaginella lepidophylla'), and this has the same power 

 of rapid resuscitation. Many mosses and liverworts 

 show the same thing, the whole plant drying up 

 completely and reviving a] most instantaneously on 

 being moistened. Less commonly in these plants 



