Transpiration and Behaviour of Stomata in 
Halophytes. 
BY 
E. MARION DELF. 
With thirteen Figures in the Text. 
I. Introduction. 
S ALT-MARSH plants are of some interest because, whilst apparently 
aquatic in habit, they show features, such as succulence, reduction in 
leaf surface, and even hairiness (in tropical forms), which are commonly 
associated with a distinctly xerophilous habit. 
As early as 1888 Lesage noticed that many plants common to littoral 
and inland regions were constantly rather more succulent when in the 
former position, and this led him to undertake an extensive series of culture 
experiments in order to see whether the thicker leaves could be produced 
artificially by watering with a solution of sodium chloride. The results 
were variable, but in Lepidium sativum and some other cases there was 
a distinct increase in thickness and a tendency towards diminution in the 
leaf surface. In 1891 Schimper found that watering inland plants with 
saline solutions caused a distinct reduction in the rate of transpiration, and 
in some cases appeared to have an injurious effect on assimilation ; and that 
in certain cases plants watered with weak solutions showed a distinct accu- 
mulation of chlorides within the mesophyll cells of the leaf. The explana- 
tion advanced by Schimper and accepted by Pfeffer 1 and Dr. Ludwig Jost 1 
was to the effect that these plants are unable to absorb water freely from 
the soil, owing to the danger of thereby bringing into the tissues injurious 
amounts of salts. Since the absorption is thus limited, the transpiration 
must needs also be diminished, and this is brought about by the various 
xerophilous adaptations to which allusion has already been made ; or in 
the words of Schimper, the watery habitat must be regarded as being 
c physiologically dry ’. 
1 Pfeffer, Phys. of Plants, Eng. Edition, vol. i, p. 155. Cp. also Jost, Lectures on Plant 
Physiology, 1907, Eng. Edition, p. 97. 
[Annals of Botany, Vol. XXV. No. XCVIII. April, 1911.] 
K k 
