392 The Living Plant 



sistent ovary, modified to aid dissemination, and often accom- 

 panied by contiguous parts of the flower, which constitutes the 

 fruit of the plant. 



For the sake of completeness I should add yet another to the 

 methods by which the wind aids dissemination, although it is 



only of minor importance. Not 

 only seeds, but some other parts 

 of plants which are capable of 

 growth, are also transported by 

 winds, especially when these rise 

 into gales. It is thus with some 

 leaves, in Begonias and Life-plants 

 (Bryophyllum) ; joints of stem in 

 some Cactuses; buds or bulblets in 



Fio. 162. The Rose of Jericho, ex- 

 plained in the text. (Reduced from some Sedums and Lilies; the brittle 



Kerner's Pflanzenleberi) . . ~ -^7.,, mi r , , , , 



twigs of Willows. The fact that in 



such cases the transport is incidental rather than adaptively de- 

 veloped makes it none the less real; while moreover, the very acci- 

 dentality of the method illustrates to perfection the way in which 

 many, and perhaps most, adaptations begin. Again, some kinds 

 of plants that live in open dry places roll their branches inwards at 

 times to form a kind of ball, and in this state may be blown from 

 their anchorage and sent rolling across plains or the frozen snow, 

 to take root again in new places, often scattering their seeds or 

 spores as they go. Such plants, called " tumble-weeds " and es- 

 pecially characteristic of prairies or plains, are well exemplified in 

 the Russian Thistle, a troublesome new weed of the west, the Rose 

 of Jericho, mentioned at times in the Scriptures (figure 162), and 

 the Resurrection Plant of the southwest. Sometimes it is not the 

 whole plant but only its fruit-cluster, as in members of the Parsley 

 Family, which is thus broken loose and sent rolling away. A 

 simpler method is displayed in those flat pods, such as some 

 Locusts possess, which, curling into loose spirals that catch every 

 wind, are rolled over smooth ground or the snow. 



