Genera Ceraria and Portulacaria. 1 1 1 5 
structure could not be determined (PI. XCVIII, Fig. 5). A small amount 
of parenchyma occurs in the phloem, but companion cells have not been 
recognized with certainty. 
Cambium. The xylem is separated from the phloem by a definite 
cambium, usually two or three cells wide. 
Xylem. The most striking feature of the xylem is the entire absence 
of bordered pits, 1 simple pits being found in the vessels, tracheides, 
parenchyma, and fibres. The pits are often horizontally elongated, though 
Text-fig. 2. Ceraria namaqitensis. Diagrammatic representation of a transverse section 
through the stem. P = pith ; i.c. = inner cortex ; m.r. = mucilage ring ; ox. = outer cortex ; b = 
bark, x 16. 
not enough so to justify the use of the term scalariform. Lignified 
parenchyma cells are present, but not to any great extent. Fibres are 
abundant as in the phloem, differing, however, in this case in being slightly 
pitted. The pits are more numerous on the walls adjoining the other xylem 
elements than elsewhere. Spiral tracheides, constituting the protoxylem, 
show no peculiarities. 
Pith . The pith is small in amount, and consists entirely of parenchyma. 
1 Solereder (’08), pp. m and 113. 
