Development of the Vascular System in the Fertile Floret of Anthoxanthum odoratum L. (Gramineae). II. Sieve-Element Plexus, Stamen Traces, and the Xylem Discontinuity

1987 ◽  
Vol 148 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Kay Robinson-Beers ◽  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Sieve Element ◽  
Anthoxanthum Odoratum

Vascular system of the floret of Alopecurus carolinianus (Gramineae)

1987 ◽  
Vol 65 (12) ◽  
pp. 2592-2600 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Sieve Elements

The interconnecting vascular system of the floret of Alopecurus carolinianus Walter begins as a single, collateral bundle, which enters the rachilla and becomes reorganized into a diarch pattern while ascending between the glumes. During a pronounced posterior enlargement, the rachilla bundle becomes connected with the median and four lateral bundles of the lemma. Above the trace to the lemma median, elements of a xylem discontinuity surrounded by those of a sieve-element plexus form in the rachilla bundle. Higher, a trace consisting of elements of the xylem discontinuity and the plexus enters the anterior and the posterior stamen. Two bundles, the lowest portion of the pistil vasculature, rise eccentrically from the xylem discontinuity and sieve-element plexus at the level of the stamen traces. The bundles condense into one which rotates counterclockwise and connects with the anterior sieve tube of the pistil. The xylem discontinuity of the bundle now in the pistil begins to diminish, and the sieve elements fan out to the sides and posterior of the xylem discontinuity. From the sieve elements one or two posterolaterals emerge toward the styles. The bundle of diffuse sieve elements in a semicircle behind the diminishing xylem discontinuity is now the placental bundle of the pistil. After its xylem discontinuity and then its sieve elements fade out, the placental bundle merges with the ovule at the chalaza.

Vascular system of the fertile floret of Phalaris arundinacea

1989 ◽  
Vol 67 (5) ◽  
pp. 1366-1380 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Lower Layer ◽  
Phalaris Arundinacea ◽  
Sieve Element ◽  
Vascular Bundles ◽  
Tracheary Elements ◽  
Sieve Elements

Six vascular bundles lie in two rows of three in the rachilla at the base of the fertile floret. Each bundle relates to a lemma or palea trace. As the rachilla bundles become traces they also produce sieve elements that interconnect to form the lower layer of the sieve-element plexus. Lodicule traces join the anterior of this lower plexus. Only the tracheary elements from the rachilla bundle related to the lemma's median trace rise higher in the rachilla, and these merge into a system of anomalous tracheary elements (xylem discontinuity) that rises toward the ovule. The lower sieve-element plexus layer ascends around the xylem discontinuity into a trilobed upper plexus layer which supplies the stamen traces. A third sieve-element plexus (pistil plexus) joins the upper plexus layer by three descending prongs. The pistil plexus, which occurs at the base of the pistil, is linked on its anterior to the anterior bundle. The placental bundle rises from the posterior of the pistil plexus and furnishes the sides of the pistil with their anterolateral and posterolateral sieve elements. The posterolaterals supply the styles. The sieve elements and the xylem discontinuity of the placental bundle supply the ovule.

Vascular System of the Fertile Floret of Anthoxanthum odoratum L.

1984 ◽  
Vol 145 (3) ◽  
pp. 358-371 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Anthoxanthum Odoratum

Vascular system of the floret of Phleum pratense

1988 ◽  
Vol 66 (9) ◽  
pp. 1818-1829 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular Tissue ◽  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Phleum Pratense ◽  
Tracheary Elements ◽  
Sieve Elements ◽  
Circular Component

Two bundles occur in the rachilla at the floret base. The anterior bundle supplies the vascular tissue for the lemma median trace, and the posterior supplies that for its two extreme laterals. The intermediate laterals of the lemma connect at the anterior bundle, and the two palea traces join near the posterior bundle to the traces for the extreme lemma laterals. Near these connections sieve elements of the two rachilla bundles link, forming the lower component of the sieve-element plexus. The xylem discontinuity begins above the anterior bundle. An upper, circular component of the sieve-element plexus surrounds the discontinuity. The sieve elements of the lodicules join the anterior of the upper plexus. The upper plexus becomes trilobed as it merges with the stamen traces. Three pistil bundles including sieve elements and tracheary elements of the xylem discontinuity join the upper plexus. These pistil bundles unite into a circular pistil plexus surrounding the discontinuity. The anterior sieve tube of the pistil joins the anterior of the pistil plexus. Sieve elements emerge from the posterolateral portions of the plexus toward the styles and leave a placental bundle of sieve elements and tracheary elements of the xylem discontinuity in the pistil posterior.

A Scanning Electron Microscopic Study of Pro-Vascular Cellular Morphology in Chaetophora Incressata

1985 ◽  
Vol 43 ◽  
pp. 638-639
Author(s):  
A. E. Hotchkiss ◽  
A. T. Hotchkiss ◽  
R. P. Apkarian
Keyword(s):  
Green Algae ◽  
Vascular Plants ◽  
Vascular System ◽  
Higher Plants ◽  
Wall Structure ◽  
Electron Microscopic ◽  
Physiological Processes ◽  
Scanning Electron Microscopic Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Multicellular green algae may be an ancestral form of the vascular plants. These algae exhibit cell wall structure, chlorophyll pigmentation, and physiological processes similar to those of higher plants. The presence of a vascular system which provides water, minerals, and nutrients to remote tissues in higher plants was believed unnecessary for the algae. Among the green algae, the Chaetophorales are complex highly branched forms that might require some means of nutrient transport. The Chaetophorales do possess apical meristematic groups of cells that have growth orientations suggestive of stem and root positions. Branches of Chaetophora incressata were examined by the scanning electron microscope (SEM) for ultrastructural evidence of pro-vascular transport.

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