Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School



  1. The vascular bundles of Zea mays are of the monocot type, except that true amphivasal bundles are found only in the leaves.
  2. The xylem and phloem are arranged collaterally, with the xylem occupying the part of the bundle nearer the center of the stem.
  3. The xylem is composed of from 2 to 4 protoxylem elements, and two pitted vessels. The elements of the protoxylem are arranged in a radial row, and consist of 1 or 2 annular on the inside, and 1 or 2 spiral elements on the outside. Sometimes the outermost element (in respect to the stem) is a reticulate nature.
  4. The order of lignification of vessels is centrifugal. The pitted vessels appear after the formation of the protoxylem, and are arranged transverse to the row of spiral and annular tracheids.
  5. The phloem consists of sieve tubes and companion cells, with a variable number of elements. The protophloem is crushed and pushed towards the top of the bundle until it is nearly obliterated.

Library of Congress Subject Headings





South Dakota State University