260 PLANT-LIFE 



But we are not to decide rashly that leaf arrangement 

 has an invariable relation to the need of conducting 

 water to the absorptive area of the root. It is obvious 

 that such a relationship does not exist in marsh or 

 water plants, whose roots are abundantly supplied with 

 water, and have no need for a special gutter system in 

 the leaves, leaf-stalks, or stems, even if such seems to 

 exist. 



We have already stated that the root of a plant is 

 primarily a holdfast. It secures for its possessor a local 

 habitation and a fixity of tenure which varies in pro- 

 portion to the particular requirements of the case. An 

 annual plant, one that develops and perishes in a single 

 season, has a light grip of the soil, yet one that is suffi- 

 cient for its needs; but a perennial plant takes care to 

 secure a most tenacious grip of the soil, that grip being 

 the firmer in accordance with the larger growth of the 

 subject. Quite recently I clambered over rough ground 

 bestrewn with hundreds of fallen Conifers which had 

 been laid low during a very heavy gale. Among all 

 these fallen trees I did not notice a single one whose 

 trunk had snapped under stress of the wind. They were 

 all uprooted, and so tenaciously had they gripped the 

 soil by the intricate ramifications of their roots, that in 

 each case a huge mass of soil had been lifted and carried 

 by the tree when it fell. Although it was more than 

 two years since the day of this disastrous gale, many of 

 the trees when I observed them were actually growing, 

 evidently on the strength of the soil so firmly held by 

 the root system. 



The effective root-hairs (Fig. 77) are exceedingly fine, 

 with a diameter not exceeding that of a medium-sized 



