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CELLULAR BASIS FOR GROWTH AND TISSUE DIFFERENTIATION PATTERNS IN LINUM USITATISSIMUM (LINACEAE) STEMS: THE STEM UNIT
Author(s) -
Meicenheimer Roger D.
Publication year - 1992
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.1537-2197.1992.tb13674.x
Subject(s) - biology , primordium , main stem , phyllotaxis , node (physics) , stem cell , unit (ring theory) , botany , microbiology and biotechnology , meristem , genetics , mathematics , physics , shoot , gene , quantum mechanics , mathematics education
The stem unit is defined as the smallest portion of a stem that can duplicate the stem in toto through regular rotations and dilations over successive plastochrons. In stems exhibiting k ( m , n ) contact parastichy phyllotaxis, the stem unit is delimited vertically and tangentially by the boundaries of four successive leaf primordia along the m‐, n‐ , and (m + n)‐ parastichies and radially by these boundaries extended to the centroid of the stem. With the stem unit concept, node refers only to the region of actual leaf insertion, rather than the entire transverse level of insertion. Many of the conflicting and complicating aspects of the traditional node‐intemode subdivisions of stems are demonstrated, and the utility of the stem unit in circumventing these is illustrated. The stem unit is proposed as a more useful analytic subunit of the stem with which to examine stem growth and tissue differentiation processes than the more traditional node‐intemode subdivisions of stems.