50 THE AMERICAN BOTANIST 



is undoubtedly true that the greatest number of epiphytes are 

 to be found in the tropical rain forests, but our own region is 

 not lacking in them as may be realized by calling to mind the 

 many species of mosses, liverworts, algae and lichens that find 

 a situation upon the trunks of trees to their liking. Epiphytes 

 in the sea, however, appear at first glance hardly possible, be- 

 cause there are few seaweeds that grow large enough to afford 

 supports for other species. On our North-west Coast, how- 

 ever, there are submarine forests of giant kelp (Nerocystis) 

 in which individual specimens may become more than 75 feet 

 high, or rather, 75 feet long, and on the stems of such speci- 

 mens many lesser sea-weeds find a congenial resting place. It 

 seems, therefore, that practically everyvv^here on the earth 

 where large species exist, there are smaller ones ready to make 

 use of 'their taller relatives in order to get up in the world. 



Adventitious Roots. — The common definition of an ad- 

 ventitious root is one that appears in places where roots do 

 not normally grow, but there are a large number of plants in 

 which the possession of adventitious roots of this kind is so 

 regular a characteristic that it is no error to assert that the ab- 

 normal has become normal, under which circumstances the ad- 

 ventitious roots are not adventitious roots, or at least belong 

 to a different category from the ordinary roots of this kind. 

 In many plants with climbing or creeping stems, it is not un- 

 common for new roots to be put out whenever the stem comes 

 in contact with an object. The roots with which the poison 

 ivy, trumpet creeper and English ivy climb belong to this 

 group. Also when a cutting or slip is placed in moist soil, the 

 new roots developed are clearly adventitious. In rhizoma- 

 tous and bulbous plants, however, the case is somewhat dif- 

 ferent. Here, at the end of the growing season, the plants' 

 very often discard their roots and when another spring comes 

 produce new ones adventitiously. Though they may start in 

 life as seedlings with normal roots during their later years 

 they are entirely dependent upon adventitious ones. Such 



