634 



WEED FLORA OF IOWA 



Fig. 497A Pig. 497B 



Pio. 497. Seeds and fruits scattered by the wind. A. Seeds of Catalpa (.Catalpa 

 speciosa) with winged appendages. B. Key fruits of Soft Maple (.Acer 

 saccharinum) are carried by the wind and in falling drop into the mud 

 or soft grass of the lawn. 



(Drawings by Ada Hayden.) 



{Asclepiadaceae) are provided with tufts of hair which serve to 

 float the seeds in the air as they escape from the pods. The oxalis 

 family {Oxalidaceae) have seeds whose outer seed coat separates 

 from the seeds shooting them from the bursting pods. The gera- 

 nium family (Geraniaceae) have contractile pods which shoot 

 the seeds several feet from the plants. The* mustard family 

 {Cruciferae) have pods which burst but do not scatter the seeds 

 far. Many species of this group have seeds with mucilaginous 

 coats which, when in contact with damp surfaces, adhere to them. 

 Peppergrass is a well known example. This family has also some 



