146 THE NATURE STUDY COURSE. 



from where they grew. Observant eyes will see several kinds 

 of seeds that, remaining on their parent stalks until winter, 

 are moved far and wide by the wind that drifts them over the 

 snow-crusts. Many plants, such as the sedges and grasses 

 that grow near water or on land that is flooded, bear their 

 seeds in water-tight capsules. When these fall into ditches, 

 water-courses or floods they are carried to their distant homes. 

 To other seeds or fruits are attached life-preservers, bits of 

 spongy or pithy or corky substances sufficient to float the seed. 

 Examine a seed of the narrow-leafed dock for three little 

 spongy floats, or a fruit of the bur-reed for its lining of cork 

 that keeps it up in the water. 



Balloonists. — The basswood places each little cluster of nuts 

 on a bract which may serve for a toboggan, or a sail or a 

 wing. The dandelion, the poplar, and the thistle have a host 

 of imitators that in dry weather spread their downy para- 

 chutes to be caught by the wind, carried aloft and floated 

 until a shower wets their sails and brings them to the earth, 

 rain-softened to receive them 



Riders and Creepers. — Some of the riders pay their way 

 like the cherry, hawthorn and ivy, whose fruits the robin or 

 crow may eat for the pulp but whose seeds are protected from 

 digestion by their stony walls ; or like the euphorbia whose 

 caruncles reward the busy ants for their share in the distri- 

 bution of such seeds. Others like the burdocks and pitchforks 

 and stickseeds steal their rides. With sharp hooks they catch 

 the wool of the passing sheep or the hair of the shaggy dog. 

 The hooks or barbs of such kinds of seeds or fruits are as 

 curious as they are effective for their purpose but many of 

 them require a good lens or microscope for their examination. 



Some of the grass seeds like those of porcupine grass and 

 wild oats have twisted awns which straighten or curl and twist 

 according as they are wet or dry. Each act of straightening 



