S s'YSTFMATir POMOLOCY 



must often choose sjxM-ics and vaiit't>- in accoi-daiice witli the 

 lial)its of tlie roots. 



14. Duration of roots. — Roots whidi live only one y<'ar are 

 annuah: those wliieli live tlirou<ih two ^ro\vin«i: seasons are hieii- 

 nials; tliose wliicli survive moi'e than two years, more particu- 

 larly lliosc which live year after year, are perennials. TIk* 

 ])oniol()<rical plants are perennial, but the strawberry is often 

 grown as a biennial. Both j)laiit and root are annual or bien- 

 nial in any one species, but annual stems may arise from peren- 

 nial roots; these are herbaceous perennials, the stems of which 

 are more or less succulent. Perennial stems are hard and woody, 

 of which all shrubs and trees are examples; these are described 

 as woody perennials. Because of lack of facts, it is difficult 

 to set definite figures for ages of perennials, but every .species, 

 as with animals, is limited to a certain age. 



15. Rooting habits of pomological plants. — Root systems of 

 closely related s])ecies and varieties vary greatly both naturally 

 and according to environment. Cherries and pears send their 

 roots deeper in the soil than do peaches, plums or apples ; 

 quinces, Mahaleb cherries, Paradise and Doucin apples are very 

 shallow-rooted. The character of the root sj-stem, whether deep 

 or surface, is commonly considered when choosing a fruit for a 

 particular soil, but it is not customary to choose varieties in ac- 

 cordance with depth of rooting, yet this can be done and more 

 attention should be paid to it. 



It is obvious that in order to give fruit plants the care they 

 mo.st need it is important to take into account their natural 

 rooting habits. On this depends in large measure adaptability 

 to soil, need of water, need, frequency and kind of cultivation, 

 relations to wdnds, and the application of manures and fertilizers. 



16. Roots modified by environment. — The root systems of 

 all plants are greatly modified by external conditions, so much 

 so that they can seldom be used in classification. In particular, 

 the character and depth of soil, the amount of water contained, 

 and the climate modify roots. In deep, light, loose soils roots 

 develop more freely than in heavy compact soils. Plants in dry 

 soils usually have larger and deeper root systems than those in 

 wet soils; the roots of desert species are deep and wide in their 

 ramifications, while those of swamp plants are shallow and 



