Premium
ONTOGENY OF MAJOR VEINS IN THE LAMINA OF POPULUS DELTOIDES BARTR
Author(s) -
Isebrands J. G.,
Larson Philip R.
Publication year - 1980
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1980.tb07621.x
Subject(s) - lamina , biology , meristem , anatomy , ontogeny , secondary growth , vascular bundle , botany , xylem , shoot , genetics
The ontogeny of the major venation in the lamina of Populus deltoides Bartr. leaves was investigated in relation to the development of original procambial bundles, subsidiary bundles, and their derivatives. Serial sections and clearings were used to show that the midrib region is a composite structure consisting of several independent vascular bundles, each of which eventually diverges into the lamina to become a secondary vein. The sequence of events in the ontogeny of major secondary veins is: (1) an original procambial strand develops acropetally and becomes the precursor of the first vascular bundle of the midrib region of the lamina, (2) ground tissue at the forefront of acropetally developing subsidiary procambial bundles differentiates in a wavelike continuum; meristematic regions precede the acropetally developing procambial bundles, (3) discrete subsidiary bundles differentiate in the meristematic regions as they advance acropetally, (4) subsidiary bundles diverge obliquely in the lamina margin giving rise to the secondary veins in a basipetal fashion, and (5) subsequent differentiation and maturation of the secondary veins occurs within the lamina. The original procambial bundles and first‐formed subsidiary bundles become the secondary veins of the uppermost portions of the lamina, the next‐formed subsidiary bundles become the secondary veins of the middle portions of the lamina, and the last‐formed subsidiary bundles become the secondary veins of the lowermost portion of the lamina.