112 THE UNIVERSITY SCIENCE BULLETIN. 



Experiment Station Record ('12). Agricultural Botany, U. S. Dept. of 

 Agri., Vol. XXVII, p. 133. 



Gray, Asa; Robinson, B. L., and Fernald, M. L. ('08). Gray's New 

 Manual of Botany, 7th ed., p. 365. 



Haberlandt, Dr. G. ('14). Physiological Plant Anatomy, pp. 667-701. 



Hill, T. G. ('01). On the Anatomy of the Stem of Dalbergia paniculata, 

 Roxb. Ann. Bot., Vol. XLVII, pp. 183-186. 



Iowa Geological Survey ('13). Weed Flora of Iowa, Bull. 4, pp. 99-101. 



JOST, Dr. Ludwig ('08). Vorlesungen uber Pflanzen-physiologie, Aufi. 2, 

 p. 228, 



Peace, L. M. ('10). Plant World, Vol. Ill, pp. 93-96. 



Phytogeography of Nebraska ('00). Botan. Seminar, University of 

 Nebraska, 2d ed., pp. 157 and 217. 



Solereder, Dr. Hans ('08). Systematic Anatomy of the Dicotyledons; 

 Vol. II, pp. 645-649, 657-663, and 1155-1165. 



Stevens, W. C. ('11). Plant Anatomy, 2d ed. 



Winterstein, E., and Trier, G. ('10). Die Alkaloide, pp. 14-19. 



DESCRIPTION OF PLATES. 



PLATE I. 



Fig. 1. A photograph of a main branchlet, showing the small leaves and 

 the habit of branching. 



PLATE II. 



Fig. 2. Cross section of the stem in region I. (See fig. 29, m"); a, epi- 

 dermis; b, coUenchyma of primary cortex; c, parenchyma of primary cortex; 

 d, starch sheath between the dotted and continuous line; e, outer area of the 

 peri cycle made up of small cells; /, inner area of the pericycle made up of 

 large cells; g, primary medullary ray; h, pith; i, hair; j, primary vascular 

 bundle. X 48. 



Fig. 3. Cross section of the stem in region II. (See fig. 29, o".) The 

 woody cylinder is colored black, and the included phloem groups and larger 

 tracheae are left white. The cell walls are cellulose in the area e", which is the 

 outer portion of the pericycle area e, and are lignified in the inner portion e", 

 of the pericycle area e. Corresponding parts lettered as in fig. 2: k, leaf-trace 

 bundle in the pericycle. X 48. 



Fig. 4. Cross section of the stem in region III. (See fig. 29, p"). The 

 woody cylinder is colored black, and the included phloem groups and larger 

 tracheae are left white. Corresponding parts lettered as in fig. 2: b, leaf-trace 

 bundle; I, inner border of the innermost anomalous xylem ring; m, anomalous 

 xylem; n, active arc of secondary meristem. X 30. 



Fig. 5. Cross section of the stem in region IV. (See fig. 29, r".) The 

 cell walls of the primary medullary rays, and regions e" and /, of the peri- 

 cycle in this section, are not lignified except in the outer portion of the peri- 

 cycle area e" (this outer portion of e", colored black, being included in the 



