THE UNDERGROUND ORGANS OF A PEW WEEDS. 
BY L. H, PAMMEL AND ESTELLE D. EOGEL. 
A study of some of the troublesome perennial weeds and their methods of 
extermination has led the authors to look up the botanical descriptions of the 
underground portions and manner of propagation. 
Some writers have called all underground organs by which the plants in 
question propagate, rootstocks; others have cautiously said nothing about 
them and a few have called them roots and rootstock. It was this disagree- 
ment of authorities, in part, that made it seem desirable to make a more 
definite study to ascertain exactly how much of the underground portions are 
roots and how much are stems. This can be done only by a study of cross 
sections. Very little, so far as we know, has been published in English on the 
minute anatomy of the plants under discussion. 
The plants in which we have been especially interested are Quack Grass, 
Canada Thistle, Horse Nettle, Wild Morning Glory, Bindweed, and Milkweed. 
The present paper gives the result of our study after making stained mounts 
of all underground portions. Illustrations of the sections were made with the 
camera lucida and the photomicrograph. 
Some Morphological Views. 
The text-books on General Morphology consulted were Gray\ Robinson and 
Fernald^ Britton^ and Van Tieghem^ The special papers and bulletins were 
Hitchcock and Clothier^ Crozier®, Dewey^ Goff and Mayne®, and Hitchcock®. 
Hitchcock and Clothier state that the European iviornihg Glory (Convolvulus 
arvensis) propagates by horizontal roots. The same authors also state that the 
Wild Morning Glory (C. sepium) propagates by slender underground stems. 
The section of Convolvulus in which C. sepium occurs, Calystegia, is char- 
acterized by Dr. Gray^® as having creeping filiform rootstocks. The Milkweed, 
according to Hitchcock and Clothier, propagates by a creeping root on which 
adventitious buds appear, although Dewey states that the Milkweed and Euro- 
pean Morning Glory propagate by rootstocks. Dewey“ also states that the 
^Structural Botany, also Manual of Bot. ofv Northern U. S. (Ed. 1) 1848. XIV. 244. 
-Gray’s New Manual of Bot. (Ed. 7). 882, 858. 1908. 
^’Manual of the Flora of the Northern States and Canada. 
^Traite de Botanique. 686. 
.sBull. Kan. Agr. Exp. Sta. 76: 1-23. 
«Rep. U. S. Dept. Agr. 1886: 85. 
^Far. Bull. U. S. Dept. Agr. 28:14. 
^First Principles of Agriculture. 107. 
“The Subterranea.n Organs of Compositse. Trans. Acad. Sci. St. Louis. 9: 1, Ipl. 
i“Syn. FI. of N. A. 2:215. 
iil.c.:14. 
( 31 ) 
