321 



The roots are furnished with root-hairs, but rather sparingly ; 

 the latter condition seems quite natural with aquatic plants, 

 which are often quite devoid of them, but it is also the case 

 in the terrestrial specimens {C. venia and C. stagnalis examined). 



Generally the roots are not branching. In a few cases 

 one to four branches have been noticed e. g. in C. venia from 

 a dried-up pool at the settlement ingnukertok (in Angmagsalik- 

 fjord, Greenland 65°4o' N. Lat.) and in С hamulata from a river 

 at Miavevatn, the Færoes, gathered by С H. Ostenfeld. The 

 slender roots of the latter indicate, that the plant has been 

 submerged; it cannot with certainty be seen whether parts of 

 them have grown on the bottom. According to Lebel (1863) 

 p. 4) it was only in the latter case that the roots were branching; 

 Hegelmaier (1864 p. 29) looked in vain for branching roots 

 though, as is added, not to any great extent. Schenck (1886 b 

 p. 60) describes the root as not ramiferous. 



The central cylinder is the most simply built of the Dico- 

 tyledons, being diarch (C. stagnalis, aquatic form) or triarch 

 (6\ stagnalis, terrestrial form and С verna) (Schenck 1. c.) as 

 in Hippuris vulgaris, but with less numerous vessels than this 

 plant. The arctic roots examined agree in all essentials with 

 the description of Schenck. 



The stem, if submerged is thin and the internodes long, 

 if growing on damp places thicker with shorter internodes, 

 partly prostrate and sending out roots. 



The anatomy is that characteristic of several aquatic plants. 

 Below a thin epidermis without chlorophyll is a thick bark, 

 with large air-channels. The parenchyma contains chlorophyll, 

 in older plants it is partly resorbed. The endodermis as in a 

 root is sharply marked off towards the central cylinder. 



Hadrom and leptom are only slightly developed. As pointed 

 out by Hegelmaier (1864 p. 20) the number of the vessels vary 

 within the species being dependent on the nutritious conditions. 

 The following numbers will give an idea of the variability. 



