IOWA ACADEMY OP SCIENCE 
37 
DESCRIPTION OP PLATES. 
PLATE I. 
Fig. I. Rhizome of Lycoims ruhellus, showing scales and roots. Fig. II and III. 
Root and rhizomes of Canada Thistle {Cirsium arvense). Fig. II, st underground stem, 
r root, b buds from stems and roots, the stem from an adventitious bud at r; lateral 
roots along the stem. Fig. III. sc scales on stem, r root, b young stem from root. 
Pig. IV. European Bindweed or Morning Glory {Convolvulus arvensis). r root, b 
adventitious bud, st underground stem. Fig. V. Bindweed or Morning Glory {Con- 
volvulus sepium). Underground stem with scales at sc^ and buds at the nodes, also 
a pair of roots below the scales at r. Fig. VI. Wooly Thistle {Cirsium canescens) 
r thickened root with stems s and y from adventitious buds. All figures drawn by 
Charlotte M. King. 
PLATE II. 
Upper figure, cross section of the root of Canada Thistle {Cirsium arvense) showing 
the broad cortical parenchyma between the epidermis and the endodermis ; inner poi’tion 
showing radial bundles, the medullary rays extending into the vascular region. Lower 
figure, cross section of the rhizome of Canada Thistle {Cirsium arvense) showing ar- 
rangement of bundles. Micro-photograph by Colburn. 
PLATE III. 
Upper figure. Cross section of root of Milkweed {Asclepia^ syriaca). The vascular 
cylinder and the cortical parenchyma from which an adventitious bud has sprung. 
Lower figure. Cross section of the root of Horse Nettle {Solanum carolinense) . Radial 
bundles in center ; large cortical parenchyma cells densely filled with starch grains. 
Microphotographs by Colbuim. 
PLATE IV. 
Pig. I, Cross-section of old root of Common Milkweed {Asclepsias syriaca). ep epi- 
dermis, cor cortical parenchyma containing crystal receptacles of calcium oxalate cr, c 
cambium, xy duct, jjp parenchyma among the xylem elements. Fig. II, the woody 
root of Horse Nettle {Solanum carolinense). x ducts, pw woody parenchyma, p 
parenchyma. Fig. HI. General view of bundle root of Horse Nettle showing the ducts 
at X and the surrounding parenchyma, less magnified than in Fig. H. Pig. IV. 
Cross section of outer portion of stem of Convolvulus sepium. e epidermis, p paren- 
chyma cells with starch, a simple and compound starch grains, higher magnification than 
at p. Fig. V. Portion of root of Canada Thistle {Cirsium arvense). Cor cortex, par 
parenchyma cells of the cortex, m medullary rays, x ducts, p parenchyma, c cambium. 
PLATE V. 
Pig. I. Cross section of root of Bindweed {Convolvulus arvensis). e epidermis, h 
hypodermal layer, c cortex, n nucleus, granular cytoplasm evident, c’ cells of lower 
portion of cortical parenchyma, cam cambium, p parenchyma cells surrounding the ducts 
at X. Pig. 11. Cross-section of inner portion of root of Bindweed {Convolvulus arvensis), 
showing bundle region, parenchyma cells and five rays. Drawn by Charlotte M. King. 
Fig. HI. Portion of root of Canada Thistle, showing two large ducts and surrounding 
parenchj^ma cells. Pig. IV. Cross-section through rhizome of Quack Grass, e epidermis 
with thick walls underneath, sc sclerenchyma, par underlying thin walled parenchyma, 
end endodermis, xy ducts with thick walled sclerenchyma between pJi phloem. Pig. V 
and VI. Root of Horse Nettle {Solanum carolinense). Fig. V. Cork, cork cells and 
underneath parenchyma cells and starch grains. Fig. VI. Cortical parenchyma cells 
with starch grains. 
