Thesis - Open Access
Master of Science (MS)
The purpose of this paper is to trace the exarch primary xylem of the root, through the successive steps, to the endarch condition of the shot, and to trace also the shift from radially arranged bundles of the root to collaterally arranged bundles in the shoot for Ranunculus septentrionalis Poir., the swamp buttercup. The plants of the swamp buttercup were grown in a greenhouse. The seedlings used for sectioning were approximately 9.6 millimeters in length from the root tip to the shoot tip. The material was killed and fixed in FAA (5% formalin, 5% acetic acid, and 90% of 50% ethyl alcohol). The material was then dehydrated with alcohol, cleared in xylol, and infiltrated with paraffin according to usual laboratory methods. The sections were cut to a thickness of ten microns and stained with safranin and fast green. Photographs were taken with an A. O. Spencer Microphotographic camera and stand using a Bausch and Lomb microscope and microscope illuminator. The transition begins in the lower hypocotyl where the primary xylem and phloem have a radial arrangement. At the cotyledonary node to the protoxylem is almost endarch and the cotyledonary traces depart abruptly from the main stele and cross the cortex. The primary phloem trifurcates just below the cotyledonary node. In the base of the cotyledon, the transition is complete as the protoxylem is completely endarch and the bundle is collateral. The primary xylem is endarch throughout the foliar trace, which differentiates against the diarch plate just below the cotyledonary plate.
Library of Congress Subject Headings
Includes bibliographical references
Number of Pages
Duehr, Ronald Maurice, "Root-shoot Transition of Ranunculus Septentrionalis Poir" (1963). Electronic Theses and Dissertations. 2885.