(MIAPTKK^ VIII 

 PJIYSIOIJXHCAL CUAIIACTKU^ 



There are various i)henomeiia incidental to or a part of the 

 lihysiolo^y of plants that are often characteristic of species and 

 varieties of fruits. They cannot, as a rule, be used in forma! 

 systems of classification hut oujrht generally to be set down when 

 present in full descriptions in pomolog>'. Pomologists usually 

 include these under the very vague term constitutional char- 

 acters. Some of them are of vital importance in the business 

 of growing fruit, and belong rather more properly in a treatise 

 on fruit-growing than in a text on systematic pomology, but 

 have suffi('i(Mit value to the systematist to merit brief discussion. 



120. Hardiness. — The capacity to endure cold, which all 

 pomologists agree in calling hardiness, varies greatly in hardy 

 fruits and so helps to characterize varieties. It is, therefore, 

 worth noting as a mark of identification, and since a knowl- 

 edge of a plant's capacity to endure cold is of prime impor- 

 tance to those who cultivate a fruit, what is known of the 

 hardiness of a species or a variety must be put in its description. 

 The notion is current that acclimatization takes place in varie- 

 ties of fruit ; that is, for example, that a tender sort may become 

 more capable of enduring cold. However, scientific reporters on 

 hardiness, whether observers or experimenters, seem not to have 

 recorded cases of such acclimatization. Varieties are exceedingly 

 variable in hardiness depending on many environmental 

 conditions. 



There are other adverse conditions of climate than extreme 

 cold to which plants are more or less resistant, and which may 

 be noteworthy in a description. Plants vary much in capacity 

 to resist heat, wetness, dryness, sunlight, and shade. 



In making notes on hardiness, comparisons are valuable. 

 Thus in every locality and with every fruit, it is common knowl- 

 edge that some sorts are hardy and others less so or tender. A 



82 



