90 



THE FACTORS [Part ]' 



of lart^e quantities of salt in their nutritive solution and tluis experience a materia 

 diminution in their assimilation. Stahl's supposition that halophytes possess stomats 

 that are always rigidly open is not confirmed by O. Rosenberg's more recent investi 

 •rations. The share taken bystomata in transpiration might therefore be generallj 

 less than Stahl believed himself entitled to assume. 



ii. HALOPHYTES^. 



The amount of salt contained by halophytes is not exclusively determined 

 passively by that of their substratum, but depends chiefly on a craving foi 

 salt in the plant itself, since plants that naturally grow in such localities an 

 in ordinarj- soil also in the habit of storing up larger quantities of sodiuii 

 chloride than most non-halophytes. There are however, even among the 

 latter, a few species with this tendency, which is always combined with the 

 ability to support larger quantities of salt than other plants can endure 

 Many of these salt-loving species growing in ordinary soils appeal 

 occasionally on the sea-shore and in other habitats the salinit)- of whicl 

 keeps other plants at a distance. 



Thus the roots of Beta vulgaris, according to several analyses, contain as mud 

 3S 35-45% of chlorine in their ash. In a Cochlearia grown on sandstone 4170/ 

 of chlorine was found : Crambe maritima grown on manured land took from i 

 15-46% ; Apium graveolens up to 22-14% ; Asparagus officinalis, a facultative halo 

 ph3'te, up to 15% ; Eryngium maritimum up to 19-30%. In the ash of the horse' 

 radish, however, in the root only 1-78%, in the leaves 5-54 %, of chlorine was found 

 The micro-chemical examination for chlorine in the leaves of Indian halophyte; 

 cultivated without salt in the Buitenzorg botanic garden gave an intense reactior 

 in fourteen cases and onlj' a weak one or none at all in seven cases. 



It is worthy of note that halophj'tes are by no means uniformly distributed amon| 

 all the families of plants, but rather occur plentifullj- in certain families, while ir 

 others there are few or none. Certain families consist chiefly of halophj'tes 

 as Chenopodiaceae, Frankeniaceae, Plumbagineae, or contain large numbers 

 them, as Amarantaceae, Aizoaceae, Cruciferae, Tamaricaceae, Malvaceae, Euphor 

 biaceae, Umbelliferae, Rhizophoraceae, Lythraceae, Papilionaceae, Convolvulaceae 

 Compositae. Of families and groups which dislike salt niaj' be mentioned 

 Amentaceae, Piperaceae, Urticineae, most Polycarpicae, Rosaceae, Melastomaceae 

 Ericaceae, Orchidaceae, Araceae, and the Pteridophyta and Bryophyta. 



According to our present data, it would appear as if the representatives 

 amilies inclining towards halophily were generally richer in chlorine than those 

 of salt-avoiding families. The comparison between the contents of chlorine in boti 

 groups of families taken from Wolff's ' Ash-Tables ' is in favour of this view. But the 

 material in hand is not yet sufficient to warrant final conclusions. 



As has been stated before, halophytes can thrive on ordinary soil, foi 

 instance on garden-soil, without any addition of common salt. Indeed some 



' Schimper, II. The older literature is theie cited. 



