400 



The Living Plant 



of the world, and to establish in this country every kind of plant 



which can possibly be of service to our people. 



Before leaving dissemination it is desirable to note certain 



adaptations which are correlated therewith, though hardly a 



part of transport itself. Thus, some seeds 

 seem to possess a certain power of plant- 

 ing themselves through the movements of 

 a definite hygroscopic mechanism which is 

 so built as to bore the seeds into the ground ; 

 the wild Erodium, and the grass Stipa 

 pinnata (figure 171) are examples. In other 

 cases the ripening fruit-stalk turns away 

 from the light, and thus carries the seeds 

 into clefts of the rocks or the cliffs on 

 which the plants grow, thus ensuring their 

 fall in a place conformable to the habits 



Fig. 171. — The fruit of .S^ipa ,. ,, i ,,■,'• , c.i t ■ 



pinnata, supposedly self- ot the plant; ttiis IS true ot the Lmana 

 It texf; ''' '''''^'''''''^ "' Cymbalaria of Europe, already described 



in another connection (figure 81). Some 

 plants place the seed pods in a protective position while ripening. 

 This is common in water plants, which draw the fruit under 

 water by a spiral coiling of the stem, and in the Peanut, which 

 draws it underground. Others, which have seeds scattered by 

 wind, greatly elongate the stalks of the seed pods during ripening, 

 thus raising them to a position more exposed ; it is thus in the Dan- 

 delion. Some seeds become attached firmly to moist ground by 

 aid of a mucilaginous substance formed from their coats by con- 

 tact with dampness, though the advantage thereof is not clear, 

 unless the attachment aids the light weight of the seed in provid- 

 ing a resistance permitting the root to be forced more readily into 

 the ground. Again, in some pods the seeds will not all germinate 

 the same year, even under perfect conditions, but some require a 

 year longer than others, — thus ensuring the perpetuation of the 

 plants even if all the seedlings of one year are destroyed by any 



