ABSORPTION OF RAIN AND DEW IJY GREEN PARTS OF PLANTS. 177 



11. On the Preservation of Cut Flowkrs. 



Sachs, in his " Text-book of Botany," quotes the results obtained by 

 Dr. Hugo de Vries on the withering of plants as follows : — * 



" If rapidly growing shoots of large-leaved plants are cut off at their lower part 

 which has become completely ligniried, and are placed with the cut surface in water, 

 they remain for some time perfectly fresh. But if they are cut through at the 

 younger parts of the stem and are then placed in water, they soon begin to wither, 

 and the more rapidly and completely, the younger and less lignified the part where 

 the section is made. This withering can be easily prevented by making the section 

 under water, and taking care that the cut surface does not come into contact with the 

 air, the conduction of the water through the stem then suffering no interruption. 

 If care is taken that while the section is being made in the air [especially with a wet 

 knife], the leaves and upper parts of the stem lose only a very small quantity of water 

 by evaporation, withering does not begin till later, and increases only slowly after the 

 cut surface is placed in water, and the leaves again transpire." 



The cause of withering, Sachs then observes, is the interruption in 

 the conduction of water from below. This agrees with Prillieux's 

 observations,t that as soon as transpiration was checked in a faded shoot 

 by placing it in a humid atmosphere, the water held in reserve in the 

 stalk was drawn upon, and the shoot recovered. Similarly, Duchartre 

 shows that withering results from one of two causes — either that the soil 

 may not contain sufficient moisture to balance the loss by transpiration ; 

 or else the latter may proceed more rapidly than the water can be passed 

 up the stem to keep pace with it, and so fail to retain the tissues in their 

 normal state of turgescence. 



Sachs and other observers, however, all allude to the cut end as alone 

 being the place by which water is absorbed ; and. as its conductivity is 

 rapidly impaired by exposure to air, it is recommended that a sufficiently 

 long piece of the stem should be removed by a new cut above the first, 

 but this time beneath the surface of the ivater. For a shoot about 

 8 inches long, 2 or 2i inches should be cut off. 



Now Bonnet's experiments and my own clearly show that absorption 

 can take place through the surface of herbaceous steins and by leaves as 

 well as the cut ends. This fact led me to presume that it would be 

 judicious to retain one or more leaves upon a flower-stalk, as well as to 

 allow the stalk itself to be of considerable length, if the inflorescence was 

 to be retained without withering as long as possible. 



It was found, however, that if the flowers are well nigh at maturity, 

 the additional impetus given to them by the extra absorbing surface 

 hastened them too much, so that the petals would fall early ; but, on the 

 other hand, when the stem was ligneous, as of lilac, or the inflorescence 

 chiefly in buds, as of Tradescantia and Compositae, then the advantage 

 was apparent ; so that, instead of the buds perishing, they continued to 

 expand successively. 



A certain amount of judgment would, therefore, seem to be necessary 

 in forming a bouquet as to the desirability of retaining some leaves or 

 not ; but if the principle be understood that it is a question of " supply 



* P. 606, Eng. ed. 



f " Experiences sur la fanaison des ITantes," Comptes Rendus, t. lxxi. p. 80. 1870. 

 VOL. XXXIV. N 



