212 



SEED AND FRUIT DISPERSAL 



seed far from the plant. The bean pod will throw its 

 seeds widely when the valves open suddenly and coil. The 



FIG. 134. Seed Dispersal by Wind. 1, Boneset (Eupatorium perfolia- 

 tuni) ; 2, arnica (Arnica montana) ; 3, spreading dogbane (Apocynum andro- 

 scemifolium) ; 4, sycamore (Platanus occidentalis) ; 5, clematis (Clematis sp.) ; 

 6, swamp milkweed (Asclepias incarnata) ; 7, common milkweed (Asclepias 

 syriaca); 8, linden (Tilia ameiicana). By water, 9, sycamore (Platanus 

 occidentalis"). By animals. 10, beggar-ticks (Bidens frondosa) ; 11, cockle-bur 

 (Xanthium echinatum) ; 12, common burdock (Arctum minus)- 13, avens 

 (Geum sp.) ; 14, cherry (Prunus cerasus) . By mechanical force. 15, witch 

 hazel (Hamamelis virginiana) . 



