610 BRITTON : VEGETATION OF THE 
Lrnaria CANADENSIS. — Primary root shows three vessels in 
center surrounded by phloem. Endodermis distinct, of small cells 
that appear oblong in cross-section. Outside of the endodermis 
are three rows of very large cortical cells, circular, pentagonal or 
oblong in transverse section. In secondarily thickened root the 
vessels are not large, and are pitted. The cortex is a thin layer of 
large thin-walled cells. 
Diameter of root, .0o9 mm. 
*¢ -** central. cylinder, .o2 mm. 
oy ‘* largest vessels, 4B. 
Curysopsis FALCATA. — A cross-section of the xylem of the 
primary root shows a four-pointed radial arrangement, with two 
large vessels and two small ones in the center. Endodermis ap- 
parent, cells nearly ciréular in transverse section, with thin walls. 
Pericycle of similar structure. The cortical tissue is formed of 
about eleven layers of large colorless parenchyma-cells, circular in 
cross-section, with thin walls, and intercellular spaces. Walls of 
the two outer layers are brown in color. 
Diameter of root, .45 mm. 
«« “© central cylinder, .13 mm. 
‘¢ © - Jargest vessels, 17 pt 
SOLIDAGO NEMORALIS.— Bundle has diarch arrangement in 
young root, and the vessels are very small. _Endodermis is appa- 
rent, and the cortex is made up of large cylindrical cells with con- 
tents plainly visible. In roots that have undergone some se¢- 
ondary thickening there are several good-sized vessels and the 
cortical cells are large and colorless with large intercellular spaces, 
while the endodermis can still be made out. The structure closely 
resembles that of Chrysanthemum Leucanthemum. 
Diameter of root, 55 mm, 
**  ** central cylinder, .26 mm. 
‘* — * Jargest vessels, 43 4 
IONACTIS LINARIIFOLIUS. — Primary structure of root has a 
bundle with three-pointed xylem in cross-section and containing 
three large vessels. Endodermis is prominent and is composed 
of thin-walled cells which vary from rectangular to circular in 
