Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 525718
Title Histological investigations of the secondary phloem of gymnosperms
Author(s) Outer, R.W. den
Source Wageningen University. Promotor(en): A.L. Stoffers. - Wageningen : Veenman - 118
Publication type Dissertation, internally prepared
Publication year 1967
Keyword(s) bosbouw - bomen - naaktzadigen - floëem - cytologie - plantenweefsels - forestry - trees - gymnosperms - phloem - cytology - plant tissues
Categories Forest Ecology
Abstract An anatomical study of secondary phloem of the different species of Gymnosperms showed that three categories could be distinguished, which may represent three evolutionary stages. These three categories were:

Pseudotsuga taxifolia type, to which belong many Pinaceae (while the other Pinaceae species belong to a subtype, e.g. the Tsuga canadensis subtype);

Gingko biloba type, to which belong the Cycadaceae, Araucariaceae and many Podocarpaceae and Taxaceae;

Chamaecyparis pisifera type, to which belong the Cupressaceae, Taxodiaceae and the rest of the Taxaceae and Podocarpaceae.

The phylogenetic sequence of the axial system and the reduction of the phloem rays starts in the Ps. taxifolia type with an almost uniform axial system and ray- albuminous cells, and a complex heterogeneous phloem ray, differentiating through the G. biloba type to the C. pisifera type, which has a highly specialized axial system with phloem-albuminous cells and a simpler, reduced homogeneous phloem ray. The reduction of the phloem rays parallels the differentiation of the axial system.

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