DISPERSAL AND SURVIVAL OF PLANTS 



Table 4 

 Natural Dispersal Limits of Fruits, Pollen, and Spores (after Geiger, 1950) 



197 



Then, seeds blown over sea-ice by the wind would seem to have a better 

 chance, but this will be considered below 



The role of the wind as a long-distance dispenser of plant material is 

 perhaps the most important one (Ridley, 1930; Sahsbury, 1942, etc.). It is 

 well known that very many plants are equipped for wind-dispersal, and a 

 lot of seeds and fruits have extra appendages making this sort of dispersal 

 especially feasible. 



There is, however, a substantial difference between wind-dispersal over 

 moderate distances and dispersal over such long ones as we deal with here. 

 Fruits and seeds equipped with plumes, wings, and similar arrangements may 

 not fly long distances at all, because their settling rate, which is dependent on 

 the weight and dimensions of the seeds, is too fast (Ridley, 1930; Geiger, 

 1950). The only particles which actually can serve as a sort of "air-plankton" 

 and be carried very far from the mother plants are spores, pollen, and similar 

 microscopical bodies (cf. Tables 4 and 5). But even these do not go very far if the 

 wind dispersing them is faint or occurs in stratified layers as is not seldom the 



Table 5 

 Experimental dispersal limits of Papaver seeds (after Salisbury 1942). The seeds 



WERE disseminated FROM THE CAPSULES BY AID OF WIND, DELIBERATELY MADE TURBULENT, 

 BY AN ELECTRICAL FAN. ThE GERMINATION CAPACITY OF THE THUS DISSEMINATED SEEDS WAS 



TESTED. 



