
26 BOTANICAL GAZETTE [JANUARY 
structure as in the leaves, under which they will be described. 
Underneath the epidermis is either a chlorophyll bearing corti- 
cal parenchyma (in the furrows) or a mechanical tissue (in the 
ridges). The former in our species occurs in nearly rectangu- 
lar groups in transverse section, separated from one another by 
the mechanical tissue. There is but one stratum of palisade 
cells, directly beneath the stomatiferous epidermis; while the 
other part of the green cortex consists of loosely connected 
cells of irregular shape and with very wide air spaces. No 
proper lacunes are developed in the cortex, nor are there any 
such diaphragms as in the leaves. 
The mechanical tissue constitutes quite a prominent portion 
of the stem section. It is this tissue which forms the eight 
ridges, and it extends inwards to the mestome bundles, which it 
surrounds as a closed ring, and also occurs as a few layers on 
the hadrome side of the mestome bundles. <A close examina- 
tion of this tissue, however, shows that even if it may be desig- 
nated as ‘“‘mechanical” throughout, it nevertheless represents 
two distinct kinds of tissues, collenchymatic and stereomatic, 
both somewhat modified in our species. The collenchymatic 
tissue reaches its highest development in the ridges of the scape, 
just beneath the epidermis. i1t appears there composed of dis- 
tinctly thickened cells, but roundish in cross section and with 
plainly visible intercellular spaces; viewed in longitudinal sec- 
tions these cells are rectangular and quite long. As mentioned 
above, this tissue extends inwards between the groups of green 
cortex to the mestome bundles, and occurs here as a closed ring 
of two or three strata. I have been unable to discover any dis- 
tinction between the strata which surround the band of mestome 
bundles and those which form the ridges. The thickening of 
the cell walls is of course most pronounced in the ridges, and 
especially near the epidermis, but if the tissue is followed 
inwards to the mestome bundles the thickness decreases very 
gradually, and the shape of the cells remains the same in both 
longitudinal and transverse sections. The term “ collenchy- 
matic,’ as suggested by Schwendener for this special tissue in 


