160 EFFECTS OF EXCESSIVE WINTER-WET. 



loses its roots by rotting, or becomes unnaturally susceptible of 

 the influence of cold in rigorous climates, or is driven prema- 

 turely iato growth, when its new parts perish from the 

 unfavourable state of the air in which they are then developed. 

 The most suitable condition of the soil, at the period of vegetable 

 rest, seems to be that ia which no more aqueous matter is 

 contained than results from the capillary attraction of the 

 earthy particles. 



During the season of 1852 and 1853, in wMcli rain fell, witli little inter- 

 mission, from November till March., and inxmdated permanently gardens 

 in low situations, Ehododendrons, although fond of moisture, perished 

 to a great extent. During winter they seemed to be healthy, but when 

 spring arrived their leaves became dull, changed to brown, and withered, 

 and the buds refused to push ; or, when attempts were made by planta 

 to renew their vegetation, their growth was feeble, and most of them 

 died in the course of the following autumn or winter. 



Nevertheless, there are exceptions to this, in the case of 

 aquatic and marsh plants, whose peculiar constitution enables 

 them to bear with impunity, during their winter, an immersion 

 in water ; and in that of many kinds of bulbs, which, during their 

 season of rest, are exposed to excessive heat and dryness. The 

 latter plants are, however, constructed in a peculiar manner; 

 their roots are annual, and perish at the same time as the leaves, 

 when all the absorbent organs being lost, the bulb cannot be 

 supposed to require any supply of moisture, inasmuch as it 

 possesses no means of taking it up, even if it existed in the soil. 



The conditions under which true ac[uatics exist have been so well 

 explained by a philosophical writer, in the ~ Gardener's Chronicle, 

 1852, p. 19, that I quote his statement without curtailment, although 

 his remarks, in part, refer to other questions besides the moisture of ^e 

 medium in which roots are placed :^— 



Plants growing entirely under water are to some extent protected 

 from those great and sudden changes of temperature to which ordinary 

 land plants are frequently exposed ; at the same time, however, water 

 plants are very often injured by cold, and it not unfreqiiently happens, 

 that on a cold winter's night plants in a pond will be greatly injured, or 

 even killed, whilst those in a neighbouring pond will remain quite 

 uninjured. In order to understand the precise cause, of this pheno- 

 menon, we must examine the conditions under which plants grow, and 

 the peculiar sources of injury to which they are "consequently exposed. 



