95 
Triglochin maritimum , L. 
In common with the roots of many other Monocotyledons, 
e. g. Aponogeton and Potamogeton lucens , according to Van 
Tieghem ( 14 #), each phloem-group in the roots of Triglochin 
maritimum is reduced to one sieve-tube with its companion-cell. 
In the very young regions of the roots the mother-cell 
of the sieve-tube and companion-cell is seen as a six-sided 
element, somewhat larger than its neighbours. As it increases 
in age a periclinal wall arises, dividing the cell into an outer 
cell, which is the sieve-tube, and an inner segment, which is 
the companion-cell. The sieve-tube abuts directly on the 
endodermis, thus interrupting the pericyle at this point. 
It is somewhat difficult to demonstrate the presence of the 
sieve-plate ; not one was clearly seen in the younger parts 
of the root; Fig. 14 illustrates these structures as they were 
found in the oldest part of a root embedded in the cortex 
of the rhizome. From this figure it may be seen that the 
sieve-tube is undoubtedly next the endodermis, and in this 
case the sieve-plates are typical and of the simple type 
of structure. 
Van Tieghem figures and describes the pericycle as a con¬ 
tinuous layer, with the sieve-tube abutting on it, and he does 
not appear to have noticed the companion-cell. In all cases 
the sieve-tube is in contact with the endodermis and interrupts 
the pericycle, and the companion-cell is easily recognized 1 . 
In longitudinal section the protoxylem is seen to be 
composed generally of annular elements. 
The apex of the root of Triglochin maritimum so closely 
resembles that of Zea Mais that it hardly calls for an 
extended description. 
The roots do not frequently branch, so that preparations 
showing the first origin of lateral roots were not obtained. 
From young lateral roots, still embedded in the cortex of the 
mother root, it appears that they arise from the pericycle 
opposite the protoxylem-groups. 
1 It would perhaps he as well to note here that Figs. 33 and 35 in Van Tieghem’s 
paper appear to be wrongly numbered. Fig. 33 seems to refer to Aponogeton , and 
Fig- 35 to Triglochin , instead of vice versa. 
