328 BOTANICAL GAZETTE [MAY 
In Ruellia the structure is that of a land plant as follows: the hairy 
root with a solid cortex and with many sclerotic cells; the very hairy 
stem with a closed sheath of stereome inside the endodermis; the 
very hairy leaves held in a horizontal position and with a strictly 
bifacial structure in regard to stomata and palisade tissue. In the 
aquatic Dianthera, on the other hand, the roots are glabrous (at least 
in adult specimens) and the cortex is collapsed; the stem has only 
small, glandular hairs and the cortex shows intercellular spaces of 
sometimes enormous width; the narrow leaves are held in a vertical 
position and are approximately isolateral, so far as concerns the 
stomata and palisade cells; in addition to the glandular hairs only 
very short and mostly unicellular hairs cover the margins of the 
younger leaves. 
BROOKLAND, D. C. 
EXPLANATION OF PLATES XI anv XII 
Ruellia ciliosa 
PLATE XI 
Fic. 1. Transverse section of root, showing sclerotic cells in the cortical paren- 
chyma. , 
Fic. 2. Longitudinal section of a sclerotic cell. 320. 
G. 3. Epidermis of lower face of leaf, showing two stomata, a cystolith, 
and a ie hair, viewed en face. X 320. 
Fic. 4. Hair from lower face of leaf. 240. 
Fic. 5. Transverse section of part of midrib of leaf, showing the leptome 
extending between the hadromatic rays: end, endodermis; /, leptome; /, had- 
rome. 560. 
Fic. 6. Transverse section of part of leaf, showing the palisade tissue (p) 
extending above the midrib: h, the hadrome of the small lateral mestome bundle; 
coll, collenchyma, X 230. 
Dianthera americana 
Fic. 7. Transverse section of a secondary root, showing the beginning of 
growth in thickness: c¢, cortex; end, endodermis; p, pericambium; between the 
two rays of vessels and inside the leptome is an arch of cambial tissue and a 
spa. wide, and very thin-walled vessel. 
G. 8. Transverse section of a secondary root: as epidermis; ex, exodermis 
of ke layers. 320. 
Fic. 9. Transverse section of stem internode, showing eight strands of col- 
bead (coll) separated by palisades, the peripheral strata of cortex (c), and 
