Patterns of Pollination in the Primitive Angiosperms

Biotropica ◽  
1980 ◽  
Vol 12 (1) ◽  
pp. 1 ◽  
Author(s):  
Leonard B. Thien
Keyword(s):  
Primitive Angiosperms

INFLORESCENCE STRUCTURE IN PRIMITIVE ANGIOSPERMS

Taxon ◽  
1988 ◽  
Vol 37 (3) ◽  
pp. 657-690 ◽  
Author(s):  
Focko Weberling
Keyword(s):  
Primitive Angiosperms ◽  
Inflorescence Structure

Isozyme Evidence for Ancient Polyploidy in Primitive Angiosperms

1990 ◽  
Vol 15 (2) ◽  
pp. 328 ◽  
Author(s):  
Douglas E. Soltis ◽  
Pamela S. Soltis
Keyword(s):  
Primitive Angiosperms

Parallelism and Reversibility in Xylem Evolution a Review

IAWA Journal ◽  
1996 ◽  
Vol 17 (4) ◽  
pp. 351-364 ◽  
Author(s):  
Pieter Baas ◽  
Elisabeth A. Wheeler
Keyword(s):  
Phylogenetic Analyses ◽  
Distribution Patterns ◽  
Seed Plants ◽  
Hydraulic Architecture ◽  
Primitive Angiosperms ◽  
Perforation Plate ◽  
High Incidence ◽  
Fusiform Initials ◽  
Plate Type ◽  
Transformation Series

The irreversibility of the major trends of xylem evolution, such as the origin of vessels in primitive angiosperms with long fusiform initials, and the shifts from scalariform to simple perforations and from tracheids to libriform fibres, has long been accepted by wood anatomists. Parallel development of these and other xylem features is generally accepted, and is suggested by the distribution patterns of the fibre and perforation plate type. Some recent phylogenetic analyses of seed plants suggest that there also have been some reversals in these general trends. The likelihood and extent of parallel origins and reversions of the major trends in xylem specialization are explored here by analysing a number of published hypotheses on the phylogenetic relationships within wood anatomically diverse major clades of angiosperms, and within some individual families. On the basis of these analyses, it appears that for these major Baileyan transformation series, parallelisms were more than twice as common as reversals. Functional adaptations to increased efficiency and safety of hydraulic architecture can largely explain the high incidence of parallelisms in xylem evolution.

Late Cenozoic pollen spectra from the Atherton Tableland, north-eastern Australia

1982 ◽  
Vol 30 (3) ◽  
pp. 279 ◽  
Author(s):  
AP Kershaw ◽  
IR Sluiter
Keyword(s):  
Pollen Analysis ◽  
Climatic Conditions ◽  
Early Pleistocene ◽  
Late Cenozoic ◽  
Contributing Factors ◽  
Primitive Angiosperms ◽  
Modern Pollen ◽  
Late Tertiary ◽  
Eastern Australia ◽  
North Eastern

Pollen analysis of samples from a short sediment sequence on the Atherton Tableland, of Late Tertiary or Early Pleistocene age, provides the first evidence of existing vegetation within the region prior to about 100,000 years B.P. Comparison of fossil samples with modern pollen spectra suggests the presence of a submontane rainforest existing under a temperature regime some 3°C cooler than present. A number of ancient taxa including Nothofagus and several conifers, present in the fossil samples, no longer exists within the region. An attempt is made to explain their decline within an area that harbours a great diversity of rainforest species including many primitive angiosperms. Unfavourable climatic conditions combined with aspects of the dispersal ecology of the taxa would have been important contributing factors.

Vessel Occlusions in Plants: Morphological, Functional and Evolutionary Aspects

IAWA Journal ◽  
1990 ◽  
Vol 11 (4) ◽  
pp. 393-399 ◽  
Author(s):  
Karel J. M. Bonsen ◽  
Ladislav J. Kučera
Keyword(s):  
Functional Significance ◽  
Vessel Wall ◽  
Plant Evolution ◽  
Anatomical Feature ◽  
Vessel Occlusion ◽  
Aperture Diameter ◽  
Primitive Angiosperms ◽  
Evolutionary Hypothesis ◽  
Evolutionary Aspects

The minimum pit aperture diameter of a vessel-parenchyma pit pair was found as the decisive wood anatomical feature for vessel occlusion by either tyloses or gums. Based on this observation, as well as on considerations and established knowledge about the functional significance of vessel occlusions, an evolutionary hypothesis is presented. In order to withstand microorganisms and embolisms, plants are able to occlude their vessels with tyloses or gums. The most primitive Angiosperms show tylosis formation. With the decreasing pit sizes in the vessel wall during plant evolution, gum formation was developed, whereas the increasing vessel sizes led in some plants to renewed tylosis formation.

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