Development of vascular bundles during primary growth of stem

Diagrams showing changes in a shoot of a dicotyledonous plant during primary growth.

(A) = a longitudinal section of shoot from apical meristem to completion of primary growth; the length of the stem is shortened. (B) through (E) = cross-sections of shoot cut at positions indicated. Shown are the initiation and development of eight open collateral vascular bundles.

1 = apical meristem, 2 = procambium, 3 = protoderm, 4 = ground meristem, 5 = primary phloem, 6 = primary xylem, 7 = leaf trace, 8 = pith ray, 9 = pith, 10 = epidermis

Illustration adapted from: Weier, Stocking & Barbour, 1974, Botany: An Introduction to Plant Biology, 5th Ed. This material is used by permission of a subsidiary of John Wiley & Sons, Inc.