The Morphology of Ruppia Maritima. 113 
merged Potamogetons, such as P. filiformis, have a similar root 
structure. 
Another plant, whose roots resemble closely in internal structure 
those of Ruppia, is A/thenia filiformis. Epidermis, exodermis and 
cortex are practically identical with the same tissues in Ruppia, and 
although Prillieux’s (1864) description and figures of the bundle leave 
much to be desired, there is evidently a strong resemblance to 
Ruppia. 
The structure of the mature root of Cymodocea apparently differs 
entirely from our plant, most certainly in the composition of the 
central cylinder, according to Bornet’s (1864) description and figure. 
D. Functions of the Root 
As is well known, the two main functions of the root are—1. to 
absorb water and watery solutions from the soil, and 2. to act 
as organs of attachment. That these functions are both of much 
importance in the roots of land plants is an established fact; that 
their relative importance assumes the same proportions in submerged 
plants is not so well established. 
Some authorities, such as Sachs (1887) and Vines (1898), have 
expressed the view that the roots of submerged plants are used 
mainly as organs of attachment. Schenck (1886, pp. 57, 58) 
modifies this somewhat, concluding that the absorption is of not 
much importance, but may possibly supply mineral solutions from 
the soil. 
Strasburger’s (1891) view, as expressed in his work “Uber den 
Bau und die Verrichtungen der Leitungsbahnen in den Pflanzen,” 
is similar to Schenck’s. In the Bonn Textbook (1908, p. 165), 
however, Noll says, “ Wasserpflanzen .... verm6gen Wasser und 
geléste Stoffe iiberall an ihrer Oberflaéche aufzunehmen. .... Die 
in den Boden eindringenden Wurzeln vieler submersen Pflanzen 
tragen aber zur Ernaéhrung und zum Gedeihen dieser Wasser- 
pflanzen wesentlich bei”—thus laying considerable emphasis on the 
absorptive power of the root. 
Pond (1905) has indeed recently proved quite conclusively that 
this absorption is of more importance than was formerly supposed— 
to such a degree that, for example, in Ranunculus aquatilis tricho- 
phyllus, one of the various submerged plants he has experimented 
upon, specimens rooted in soil exceeded in growth those rooted in 
clean washed sand 62.96°/,. Similar. results were obtained by him 
with other submerged plants. 
