4io 
PHARMACEUTICAL BOTANY 
Halophytes. —The plants of this group live in a soil which is rich 
in soluble salt, usually common salt (NaCl), and on account of the 
fact that the osmotic force of the root is nearly inadequate to over¬ 
come that of the concentrated solution of the soil, the soil to such 
plants is physiologically dry. A halophyte in fact is one form of 
xerophyte. The most striking feature among halophytes is that 
they are nearly all succulent plants. The leaves of such plants, for 
example, are thick, fleshy and more or less translucent. They are 
rich in concentrated cell sap by which they are able to counteract 
the osmotic pull of the concentrated saline solution of the soils 
in which they live. Anatomically they are poor in chlorophyll, 
the intercellular-air-spaces are small and the palisade tissue is 
more abundant. Coatings of wax are found and a hairy covering, 
although infrequent, sometimes occurs. Coriaceous and glossy 
leaves, especially in tropical halophytes, are noteworthy, while 
in many salt-loving plants the stomata are sunken. Halophytes 
are found in our coastal salt marshes and on saline tidal flats in tem¬ 
perate and tropical countries and on the alkali flats of the interior 
of continents. Notable examples of these plants are the Salt Marsh 
Samphire, Salicornia ambigua , the Mangroves (Rhizopora) and the 
Bald Cypress ( Taxodium ). 
Xerophytes.-— The plants of this group, like the halophytes, are 
adjusted to live in a soil which is physiologically dry. The soil may 
owe this condition to its physical nature, such as porosity (sand), 
or to the presence of humic acicfs, or by chemical action, which in¬ 
hibits the absorption of water. They are adapted to meet the con¬ 
ditions of strongest transpiration and most precarious water supply. 
To meet such conditions of physiological drought, the plants show 
various structural adaptations. In deserts, where the atmospheric 
precipitations are less than a certain limit, the plants acquire a 
xerophytic structure, such as succulency-, water storage tissue, 
associated frequently with mucilage, lignified tissues, thick cuticle 
to the leaves depressed, stomata (frequently in pits), reduced trans¬ 
piration surfaces and thorns. Mechanical tissues like wood and 
bast fibers attain their highest development in these plants. Cacti 
and the century plant (Agave) are types of xerophytes while many 
bog plants like the cranberry and Laborador tea, with leathery leaves, 
are xerophytic. 
