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THE SHOOT APICAL ONTOGENY OF THE PICEA ABIES SEEDLING. I. ANATOMY, APICAL DOME DIAMETER, AND PLASTOCHRON DURATION
Author(s) -
Gregory Robert A.,
Romberger J. A.
Publication year - 1972
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.1537-2197.1972.tb10133.x
Subject(s) - phyllotaxis , seedling , biology , meristem , apical cell , apical dominance , botany , shoot , dome (geology) , fibonacci number , paleontology , genetics , cell , mathematics , discrete mathematics
Developing embryos in immature Picea abies seeds already have well‐delineated shoot apical meristems with clearly evident cytohistological zonation. During early seedling development the zonation characteristic of gymnospermous apical meristems is attained. Seedling development is also accompanied by an approximately threefold increase in apical dome diameter. The latter approaches a steady state about 140 days after germination. Seedlings display a spiral phyllotaxis consisting of a contact parastichy system, usually of the primary Fibonacci series. As the seedlings age and apical domes enlarge, higher Fibonacci number‐pairs characterize their phyllotaxis. Mathematical analysis of the relation between cumulative leaf number and age revealed that the length of the plastochronic time interval declines from about 18.5 hr to 5.7 hr as seedling age increases from 20 to 140 days.