18 Raymond John Pool 
palisade, three rows being arranged on each side of a median 
band of sponge-like cells which are more or less oblate in outline. 
The only indication of storage tissue is to be found in the vascular 
bundle sheath. 
This leaf seems to lack the customary protective devices of the 
xerophyte, but perhaps this is compensated for by the sensitive 
nature of the plant whereby it is able to fold its leaflets closely 
together with approaching danger of desiccation. 
Gutierrezia sarothrae. Plate IV, fig. 25. 
This species shows a well-developed, xerophyll with few epi- 
dermal hairs, well-developed cuticle, and a closely packed chloren- 
chyma. The palisade is arranged in four rows with very small © 
intercellular air spaces. Storage cells are confined to the vascu- 
lar bundle sheaths. Some of the cells of these sheaths contain 
gummy sap, and there are a few other such cells scattered in the 
region near the bundles. 
Aragallus sericeus. Plate IV, fig. 26. 
The leaf in this species is covered by a close mat of epidermal 
hairs. There is also a well-developed cuticle. The chlorenchyma 
is very loose, being composed of regular scattered prolate pali- 
sade cells. The bundles are surrounded by a sheath of clear 
storage cells. 
Lupus parviflorus. Plate IV, fig. 27. 
This species was growing in the edge of a wet meadow at Hot 
Sulphur Springs in a saturated soil. It is given here to contrast 
with figure 24, from the Artemisia formation. This species shows 
a single row of long palisade cells, with a very open sponge tissue. 
There is no storage tissue whatever. 
Delphinum ramosum. Plate IV, fig. 28. . 
This species grew in the Artemisia formation on a northeast 
slope where the soil moisture conditions were good. The leaf is 
smooth and is not covered with cuticle. The chlorenchyma is 
composed of regular prolate palisade cells very loosely aggre- 
gated. There is no sponge tissue. The vascular bundles may or 
may not be encased by a sheath of storage cells. 
428 
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