i 14 NATURE « '!•• THE SEED 



amount of 1 1 and that has temporarily stopped growing. 



The seed may be looked upon as one of the many adaptations 

 found among plants to ensure their perpetuation. From a seed 

 a single plant is developed that may produce many, often thou- 

 sands of seeds, i. <\. plantlets. We have already noted that these 

 may be widely distributed and so spread and multiply the number 

 of plants. Some seeds are so fine that they float away as a 

 dust, as in the orchids. Other seeds and fruits are provided 

 with hairs and wings that serve to buoy them up or promote 

 their transport by winds, as in the case of pine seeds, milk 



weed, willow, and the fruits of maple, dandelion, etc. In other 



spines and hooks or mucilage glands are developed that 

 attach them to any passing animal and so hrini^ about a con- 

 siderable distribution. Note the common devices of this nature, 

 a- in the burdock, stick tight, beggar lice, agrimony or the glands 

 on the nightshade (Circaea) and twin flower. So also seeds 

 are scattered by the spring of elastic stems and explosive fruits. 

 as in many lilies, witch hazel, violet, touch-me-not, etc. But 

 especially may seeds he looked upon as an adaptation to tide 

 the plant over seasons unfavorable for growth. In this respect 

 they may be compared to buds, which they also resemble in their 

 renewal of growth when condition- arc again favorable. There 



aii -..in.- noteworthy exceptions to this statement, as in the man- 

 grove, certain oaks, and many grasses. Tin' seeds of the former 

 plant begin their growth while still attached to the tree ami a 

 similar growth has also been observed in the acorns of the 

 white oak. Grain often sprouts while in the sheaves and the 



- from green tomatoes produce earlier and larger fruits. 



However the majority of seeds and fruits, as well as buds, 



not renew their growth immediately after their formation. \ 

 longer or shorter resting or dormant period is required during 



which time chemical changes OCCUr that render the foods Soluble 



and therefore available to the young plant or embryo. For ex 



ample, in man) seeds and buds the Storage foods are in the form 

 tarch. This food is insoluble and can not he used h\ the 



plant until it has been acted upon b) an enzyme which changes 

 it into a soluble and readil) diffusible sugar. These enzymes are 



