32 THE PLANT. 



upon perennial as on annual plants ; but the develope- 

 nient of the former is not so much dependent upon acci- 

 dental and passing states of the weather, as is the case 

 with the latter. Unfavourable conditions will, indeed, 

 check the growth of a perennial plant, but only for a 

 time, until a favourable change ensues, when the plant 

 will resume growing ; whereas an annual plant, under 

 the same circumstances, reaches the limits of its exist- 

 ence and dies. 



The permanence of vegetation on our meadows, and 

 the certainty of their produce under varying conditions 

 of soil and weather, must be attributed to the great 

 number of plants which are able to continue for a 

 shorter or longer period at a low stage of developement. 

 While the one species of plants is developed above 

 ground, producing flowers and seeds, a second and third 

 species gather below the surface the conditions for a 

 similar future growth. The one vegetation seems to 

 disappear, to make room for another and a third, until 

 for itself too the conditions for a perfect developement 

 recur. 



The woody plants grow and are developed in a man- 

 ner quite similar to the asparagus plant, with this dif- 

 ference, however, that they do not lose their stem when 

 the period of their vegetation comes to an end. An 

 oak-sapling, 1-J- foot high, was found to have a root 

 above 3 feet long. The stem and the root serve jointly 

 as a magazine for storing up the organi sable matter to 

 be used next year in restoring all the external organs 

 of nutrition. When the stems of lime trees, alders, or 

 willows have been cut down, they will, if lying in shady 

 moist places, shoot out afresh, often after the lapse of 

 years, and produce numerous twigs a foot long or more, 

 covered with leaves. 



The pauses which occur in the seed-bearing of forest 

 trees are similar to those which are observed in most 

 perennial plants, which, when growing on a poor soil, 

 will also take several years to collect the conditions 

 necessary for the production of fruit (Sendtner, Eatze- 

 burg). 



