80 ADA HAYDEN 
Histology: Bifacial (fig. 23, plate XIII). 
Epidermis of irregular-sized cells, convex-walled; outer wall about i 1/2 times as 
thick as inner. 
Stomata on level with lower edge of the epidermis. 
Palisade parenchyma, 2 layers; broad-celled. 
Spongy parenchyma, large-celled; rather loose; occupies 2/3 of parenchyma space. 
Resin ducts present. 
Summary: Has facilities for marked photosynthetic activity with slight protective 
device. 
Solidago canadensis L. 
Habitat: Moist soil; slopes. 
Orientation and arrangement: Ascending, somewhat appressed; sessile. 
Gross structure: Leaves narrowly lanceolate; glabrous above; minutely pubescent 
below. 
Histology: Centric (fig. 25, plate XIII). 
Epidermis thicker on upper than on lower side; outer walls about twice as thick 
as inner; trichomes on lower epidermis. 
Stomata on both sides. 
Palisade, 2 layers on upper surface and 1-2 on lower surface, occupying 2/3 the 
parenchyma space. 
Spongy parenchyma of elongated cells running at right angles to the palisade; 
compact. 
Resin ducts present. 
Summary: A typical sun leaf with moderately developed protective devices to provide 
for active photosynthesis. Consistent with its moderately moist habitat. 
Solidago graminifolia (L.) Salisb. 
Habitat: Alluvial basin; moist soil. 
Orientation and arrangement: Horizontal to ascending; sessile. 
Gross structure: Lance-linear; glabrous. 
Histology: Centric (fig. 21, plate XII). 
Epidermal cells small; outer wall 1/3 thicker on upper than on lower side; outer wall 
of upper epidermis 3 times as thick as inner. 
Palisade parenchyma, one layer on each side; cells rather small, oval; occupies 
1/2 parenchyma space of leaf. 
Spongy parenchyma cells large; fairly compact. 
Summary: Leaf fairly thin without trichomes or prominent protective device; well 
developed palisade and spongy parenchyma. 
Comparison of Leaf Anatomy of Upland and Alluvial Basin Plants 
The following plants were selected from two formations: 
I. Prairie hill crest and slope: Andropogon scoparius, Bouteloua curtipen- 
dula, Anemone cylindrica, Amorpha canescens, Ceanothus americanus, Eryn- 
gium yuccaefolium, Artemisia canadensis , Solidago canadensis, Solidago rigida, 
Coreopsis palmata, Helianthus grosseserratus, Helianthus tuherosus. 
Epidermis. Of these twelve upland plants, all have a relatively thick 
outer-walled epidermis, or prominent trichomes if the wall is not thick. 
The presence of trichomes may be regarded as an anatomical equivalent of 
thick-walled epidermis. Two have prominent bulliform cells and vascular 
bundles. (Not enough data are recorded for stomata to warrant com- 
parisons.) 
