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SEASONAL VARIATIONS IN THE SECONDARY PHLOEM OF SOME FOREST TREES FROM NIGERIA
Author(s) -
LAWTON JUNE R.
Publication year - 1972
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1972.tb04080.x
Subject(s) - phloem , sieve tube element , sieve (category theory) , botany , biology , tectona , vascular cambium , xylem , cambium , mathematics , combinatorics
S ummary The appearance of the phloem is described for the trees Albizia adianthifolia, Bombax buono‐pozense, Antiaris africana, Holarrhena floribunda, Ricinodendron heudelotii, Sterculia tragantha , and Tectona grandis. Measurements of the percentage sieve tube area, the sieve tube number per unit and the diameters of the sieve tubes have been made throughout one year. Changes in structure and composition of the phloem occurred in different ways in the several species at different times of the year. Increase in length of sieve tube elements with age was found in four of the species. In the three species with compound oblique sieve plates the pores were less than μm diameter, and the percentage sieve tube area was lower than that of the trees with phloem with simple sieve plates. The variety of phloem structure and the quantitative changes in phloem dimensions are discussed; the need for thorough investigation of phloem structure for each species as a prelude to physiological studies of the phloem is emphasized.