Intervascular Pit Membrane Structure in Daphne and Wikstroemia - Systematic Implications

IAWA Journal ◽  
1996 ◽  
Vol 17 (2) ◽  
pp. 161-181 ◽  
Author(s):  
Roland R. Dute ◽  
John D. Freeman ◽  
Frank Henning ◽  
Logan D. Barnard
Keyword(s):  
Membrane Structure ◽  
Conducting System ◽  
Tracheary Elements ◽  
Pit Membrane ◽  
Vessel Elements ◽  
Close Relationship ◽  
Helical Thickenings ◽  
Isolated Species

Intervascular pit membranes were investigated in species of Daphne, Wikstroemia, and other allied genera of the Thymelaeaceae. Results confirmed a previous study showing that, except for section Mezereum, all sections of Daphne had pit membranes with tori. Taxonomically isolated species D. aurantiaca and D. genkwa had tori, but lacked a G-layer. Tori similar in structure to those of D. aurantiaca and D. genkwa were observed in three species from the subgenus Diplomorpha of Wikstroemia. Tori of a slightly different morphology were noted in W. kudoi (subg. Daphnimorpha). Tori appeared absent from species of the subgenus Wikstroemia (= Euwikstroemia of Domke), and from the genera Drapetes, Edgeworthia, and Eriosolena. These results suggest a close relationship between Daphne and Wikstroemia. The degree of torus development and the distinctiveness of helical thickenings suggest that smaller tracheary elements serve as a backup water-conducting system to larger vessel elements.

Structure and Ultrastructure of the Tracheary Elements of Asplenium (Pteridophyta) from the “Yungas”, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (2) ◽  
pp. 227-240 ◽  
Author(s):  
María Luján Luna ◽  
Gabriela Elena Giudice ◽  
María Alejandra Ganem ◽  
Elías Ramón de la Sota
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Maturation Stage ◽  
Tracheary Elements ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Membrane Hydrolysis ◽  
Structure And Ultrastructure ◽  
Scanning Electron

The structure of root and rhizome tracheary cells of Asplenium spp. (Filicales, Pteridophyta) growing in NW Argentina was studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In all cases, tracheary cells consisted of tracheids with various facets, mainly with scalariform pitting. With SEM, intertracheary pit membranes appeared smooth and non porose in most cases. In some instances, porose or web-like to thread-like pit membranes were noticed in rhizome tracheids. Under TEM secondary walls displayed a smooth and uniform appearance. Pit membranes showed a variation in thickness in presumed association with their maturation stage. More mature tracheary cells showed pit membranes with a mesh-like aspect and visible openings or pores. These characteristics are attributed to pit membrane hydrolysis, which facilitates water transport among tracheary cells.

The Occurrence of Scalariform Perforation Plates and Helical Vessel Wall Thickenings in Wood of Myrtaceae

IAWA Journal ◽  
1984 ◽  
Vol 5 (3) ◽  
pp. 197-215 ◽  
Author(s):  
Rudolf Schmid ◽  
Pieter Baas
Keyword(s):  
Vessel Wall ◽  
Selective Pressure ◽  
Diagnostic Value ◽  
Adaptive Significance ◽  
Species Level ◽  
Tropical Species ◽  
Habitat Types ◽  
Vessel Elements ◽  
Perforation Plates ◽  
Helical Thickenings

The occurrence of multiple perforation plates and helical wall thickenings in vessel elements of 144 species (plus 12 varieties and 2 hybrids) in 53 genera of Myrtaceae was extensively explored. Scalariform perforation plates occur in 40 species (plus 1 hybrid), in Luma, Myrceugenia, Myrteola, Ugni, and in the monotypic Myrtastrum rujo-punctatum, Neomyrtus pedunculata, and Tepualia stipularis. Ugni candollei also has foraminate (i.e., sieve-like) perforation plates. Helical wall thickenings occur in 33 species (plus 1 hybrid), in Acmena, Austromyrtus, Myrceugenia, Myrcia, Myrcianthes Psidium, Xanthomyrtus, and in Myrtus communis. Most of these records are new. The speeies with exclusively scalariform perforation plates (in Luma, Myrteola, Neomyrtus, and Ugni) are from cool mesic habitats; those with mixed simple and multiple perforation plates are also largely cool mesic but show a somewhat greater diversity of habitats. Myrtaceae with exclusively simple perforation plates predominate in all habitat types. Helical wall thickenings occur sporadically throughout the distributional range ofthe family. However, tropical species tend to have weaker helical thickenings than the subtropical and temperate species exhibiting them. The possible functional significance of these ecological tendeneies is discussed. It is hypothesised that multiple perforation plates were retained in some cool mesic Myrtaceae because of a lack of strong selective pressure to eliminate them from this type of environment, rather than that they were retained because of adaptive significance in trapping embolisms. The systematic and diagnostic value of multiple perforation plates and helical wall thickenings is also discussed. Scalariform plates are largely confined to related genera in Myrtoideae; Tepualia is the only representative from Leptospermoideae. Helical wall thickenings are only of limited diagnostic and systematic value above the species level.

Torus Structure and Development in the Woods of Ulmus Alata Michx., Celtis Laevigata Willd., and Celtis Occidentalis L.

IAWA Journal ◽  
1990 ◽  
Vol 11 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Roland R. Dute ◽  
Ann E. Rushing
Keyword(s):  
Secondary Wall ◽  
Small Diameter ◽  
Three Dimensions ◽  
Central Layer ◽  
Tracheary Elements ◽  
Pit Membrane ◽  
Celtis Occidentalis ◽  
Celtis Laevigata ◽  
Ulmus Alata ◽  
Grooved Wheel

Pit membranes between tracheary elements of Ulmus alata, Celtis laevigata, and Celtis occidentalis often contained tori. The degree of development of tori varied and was greatest in those membranes connecting elements of small diameter. Complete tori consisted of two wall thickenings adjoined by a central layer. In three dimensions the shape of the torus often approximated a grooved wheel. Initiation of thickening in the pit membrane occurred first on the side of the older cell and was well underway prior to the beginning of secondary wall synthesis. Torus formation resulted from the thickening of the primary walls of the pit membrane. Development of the torus was associated with membranous vesicles and cisternae but not with microtubule complexes as was reported in Osmanthus. The pit membranes in this study are capable of aspiration, and the tori may prevent rupture of the pit membrane during this process.

Revision of the genera Cyphonethes Verhoeff, 1926 and Titanethes Schioedte, 1849 (Isopoda: Oniscoidea: Trichoniscidae) with a description of a new genus and three new taxa

Zootaxa ◽  
2018 ◽  
Vol 4459 (2) ◽  
pp. 261 ◽  
Author(s):  
IVO M. KARAMAN ◽  
MLADEN HORVATOVIĆ
Keyword(s):  
New Genus ◽  
Dorsal Surface ◽  
Comparative Morphology ◽  
Taxonomic Study ◽  
Conducting System ◽  
Adult Males ◽  
New Genus And Species ◽  
Tergal Glands ◽  
Close Relationship ◽  
A New Species

A taxonomic study of two troglobite genera resulted in remarkable changes to their composition and our perception of their relationship. The genus Titanethes is treated as monotypic, with one newly described taxon, Titanethes albus matovici n. ssp. One species is transferred from Titanethes to the genus Cyphonethes, Cyphonethes biseriatus (Verhoeff, 1900) comb. nov. A species and a genus are synonymized, Microtitanethes licodrensis syn. nov. The diagnosis of the genus Cyphonethes is amended and revised using comparative morphology of adult males. A new species, Cyphonethes tajanus n. sp, is described. A close relationship between the genera Titanethes and Spelaeonethes is established. Cetinjella monasetrii n. g., n. sp, is described as a new genus and species close to the genus Cyphonethes. It is assumed to be a higropetric cave inhabitant, based on its pereopode structure, with elongated fused dactylus and unguis, and partly by its slightly modified mouthparts. Unique water uptake (for the water conducting system) by the dorsal surface of the frontal pereionite is also assumed for the species, based on the presence, distribution and orientation of specific small scales. The presence and structure of male tergal glands in the genus Tithanethes are treated as taxonomically irrelevant. 

Ultrastructure of graniferous tracheary elements in the haustorium of Exocarpus bidwillii , a root hemi-parasite of the Santalaceae

1979 ◽  
Vol 204 (1156) ◽  
pp. 329-343 ◽  
Keyword(s):  
Xylem Sap ◽  
The Body ◽  
Fibrillar Structure ◽  
Tracheary Elements ◽  
Thin Sections ◽  
Successive Layer ◽  
Transmission Electron ◽  
Vessel Elements ◽  
Homogeneous Matrix ◽  
Dispersed Material

The xylem in the body of the haustorium of E. bidwillii has the shape of an inverted conical flask with the expanded portion being known as the vascular core. The tracheary elements of the vascular core are notable for the occurrence of numerous granules within their lumina and the presence of mostly imperforate walls. Elsewhere in the haustorium graniferous tracheary elements are absent and the cells are usually ordinary vessel elements. Thin sections for transmission electron microscopy, post-stained in potassium permanganate, show that the secondary wall thickenings of the graniferous tracheary elements consist of eccentric layers in which the microfibrils of each successive layer run alternately longitudinally and transversely. The granules of the tracheary elements average 2 μm in diameter and consist of a homogeneous matrix which shows a fine fibrillar structure on high resolution. The granules are naked and mostly remain as separate structures within the lumen of the cell, but occasionally they fuse into small groups or irregular masses. In some cells the granules become transformed into fibrillar material that disperses throughout the lumen. This dispersed material may accumulate in vessels of the interrupted zone proximal to the vascular core. Occasionally, the granules also change into compacted amorphous masses that adhere to the walls of the cell. Ultrastructural cytochemistry confirms that the granules are protein and not starch as was originally believed for the Santalaceae. The function of the vascular core and its graniferous tracheary elements is discussed and we suggest that it might help regulate the pressure and flow of xylem sap entering the parasite from the host. Graniferous tracheary elements in the Santalaceae and in root parasites of the Scrophulariaceae are compared and it is concluded that they represent examples of convergent evolution.

Extinct Juglandaceous Wood from the Eocene of Oregon and Its Implications for Xylem Evolution in the Juglandaceae

IAWA Journal ◽  
1993 ◽  
Vol 14 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Steven R. Manchester ◽  
E.A. Wheeler
Keyword(s):  
Middle Eocene ◽  
Temperate Climate ◽  
New Taxon ◽  
Common Occurrence ◽  
Axial Parenchyma ◽  
Extant Genus ◽  
Vessel Elements ◽  
The Common ◽  
Perforation Plates ◽  
Helical Thickenings

Clarnoxylon blanchardii gen. et sp. nov. is a new taxon for fossil wood with a suite of features diagnostic of the Juglandaceae. It occurs at two Middle Eocene (c. 43-44 million years b.p.) localities in the Clarno Fonnation of central Oregon, USA. Clarnoxylon resembles the Platycaryeae and the Hicorieae in having exclusively simple perforation plates and solid pith. However, the common occurrence of crystalliferous idioblasts in the rays, but not in the axial parenchyma, and the cooccurrence at Clarno of platycaryoid fmits and pollen unaccompanied by hicorioid fmits indicate that Clarnoxylon has affinities with the Platycaryeae. Differences between Clarnoxylon and Platycarya support previous suggestions that short vessel elements, helical thickenings, and vascular tracheids are derived characters of Platycarya. These differences are also in accord with the ecological adaptation of the extant genus Platycarya to a temperate climate contrasting with the tropical Middle Ebcene setting of Clarnoxylon.

Xylem Anatomy Of Diegodendron HumbertΠ

IAWA Journal ◽  
1988 ◽  
Vol 9 (4) ◽  
pp. 332-336 ◽  
Author(s):  
William C. Dickison
Keyword(s):  
Fibre Type ◽  
Wood Anatomy ◽  
Lateral Wall ◽  
Xylem Anatomy ◽  
Tracheary Elements ◽  
Axial Parenchyma ◽  
Vessel Elements ◽  
Perforation Plates

The first description of the wood of the monotypic Madagascan genus Diegodendron is provided. The xylem of D. humbertii is characterised by short , solitary vessel elements with alternate lateral wall pitting and simple perforation plates, imperforate tracheary elements of the libriform fibre type, nearly all biseriate, imperfectly storied, homogeneous rays composed of procumbent cells only, and diffuse and diffuse-in-aggregates axial parenchyma. The specialised wood anatomy of Diegodendron supports a close alliance with both Sphaerosepalaceae and Malvales.

Sign in / Sign up

Export Citation Format

Share Document