244 



REPORT ON THE 



necessary, therefore, to consider the root-growth of these plants from two points 

 of view — that of food-collecting and that of food-storage. 



The actual absorption of water is, of course, effected in the same way in 

 the roots of perennials as in those of annuals, but the perennial habit allows 

 more time wherein to work, and frequently secures a wider root-range than is 

 possible in an annual. In a perennial, cceteris 'paribus, the roots can travel 

 further, or penetrate deeper in search of food, than in the case of an annual. 



In an annual the roots, as gardeners say, " keep at home," and there is not 

 much necessity for a system of conduits to convey the water from its source to 

 the stem ; but in perennials it often happens that the best food supply is at 

 some considerable distance from the stem, and the consequence is that the 

 fibrous roots collect the liquid from the feeding-ground, and convey it in so 



Fig. 17.— eoot system of peimtjla rosea. 

 many conduits to the stem. The thicker root-fibres have, as every one knows, 

 little or no power of absorption, that faculty being mostly limited to the 

 thinnest extremities of the root-fibres, and to the root-hairs (where present). 

 Of course tne number, length, and degree of branching of the roots depend very 

 greatly on the physical nature of the soil in which the plant happens to be 

 growing— 



" Pinguibus hae terris habiles, levioribus illae." 

 But when due allowance is made for these circumstances each plant has 

 more or less its own distinct character. The roots of most species of Primula, 

 for instance, are very different from those of Androsace, and indicate different 

 requirements. [See Irmisch, in Joum. Hort. Soc. London, vol. viii. (1853), 

 p. 217.] But even in the same genus we get variations in this respect. In the 



