A silicified semiaquatic dicotyledon from the Eocene Allenby Formation of British Columbia

1973 ◽  
Vol 51 (7) ◽  
pp. 1373-1377 ◽  
Author(s):  
Coleman R. Robison ◽  
Christopher P. Person
Keyword(s):  
British Columbia ◽  
Adventitious Roots ◽  
Single Layer ◽  
Salient Feature ◽  
Anatomical Structure ◽  
Main Axis ◽  
Epidermal Cells ◽  
Coal Basin ◽  
Lateral Branches ◽  
Air Cavities

A silicified dicotyledon rhizome is described from the Eocene Allenby Formation of the Princeton Coal Basin, British Columbia. The primary and secondary vascular tissues of the rhizome form a narrow cylinder around a broad, parenchymatous pith. The rhizome's salient feature is a wide cortex in which there are numerous air cavities. In most specimens the cortex is surrounded by a single layer of epidermal cells but in some there is evidence of periderm initiation. Small lateral branches are borne on the main axis, and both the main and lateral axes bear broad, clasping leaf bases and adventitious roots. The affinities of this rhizome are presently unknown, but its anatomical structure is indicative of a semiaquatic plant.

scholarly journals Stone–Wales defects preserve hyperuniformity in amorphous two-dimensional networks

2021 ◽  
Vol 118 (3) ◽  
pp. e2016862118
Author(s):  
Duyu Chen ◽  
Yu Zheng ◽  
Lei Liu ◽  
Ge Zhang ◽  
Mohan Chen ◽  
...  
Keyword(s):  
2D Materials ◽  
Single Layer ◽  
Salient Feature ◽  
Density Fluctuations ◽  
Wave Number ◽  
Static Structure Factor ◽  
Two Dimensional ◽  
Static Structure ◽  
Topological Transformation ◽  
Amorphous Graphene

Disordered hyperuniformity (DHU) is a recently discovered novel state of many-body systems that possesses vanishing normalized infinite-wavelength density fluctuations similar to a perfect crystal and an amorphous structure like a liquid or glass. Here, we discover a hyperuniformity-preserving topological transformation in two-dimensional (2D) network structures that involves continuous introduction of Stone–Wales (SW) defects. Specifically, the static structure factor S(k) of the resulting defected networks possesses the scaling S(k)∼kα for small wave number k, where 1≤α(p)≤2 monotonically decreases as the SW defect concentration p increases, reaches α≈1 at p≈0.12, and remains almost flat beyond this p. Our findings have important implications for amorphous 2D materials since the SW defects are well known to capture the salient feature of disorder in these materials. Verified by recently synthesized single-layer amorphous graphene, our network models reveal unique electronic transport mechanisms and mechanical behaviors associated with distinct classes of disorder in 2D materials.

The Metamorphosis of Insects: Tercentenary Lecture delivered by Professor V. B. Wigglesworth, F. R. S., at 10.15 a.m. on Saturday 23 July 1960 at the Royal College of Surgeons

1961 ◽  
Vol 16 (1) ◽  
pp. 81-84 ◽  
Keyword(s):  
Epidermal Cell ◽  
Royal College ◽  
Single Layer ◽  
Secretory Activity ◽  
Epidermal Cells ◽  
Social Functions ◽  
Outer Skin ◽  
The Subject ◽  
Growth Changes

THE visible form of the insect is defined by the outer skin or cuticle. The cuticle is the product of the single layer of epidermal cells which lie beneath it. The form of the insect is thus determined by the growth changes and the secretory activity of the epidermal cell. The purpose of the lecture was to approach the subject of metamorphosis through a consideration of the physiology of the epidermal cell. The epidermal cell is interesting because it combines within itself so many functions, actual and potential; social functions as a member of the community of cells of which it forms a part, and individual functions where it is concerned primarily with its own affairs.

Permineralized fruits and seeds from the Princeton chert (Middle Eocene) of British Columbia: Vitaceae

1990 ◽  
Vol 68 (2) ◽  
pp. 288-295 ◽  
Author(s):  
Sergio R. S. Cevallos-Ferriz ◽  
Ruth A. Stockey
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Outer Zone ◽  
Structural Features ◽  
Anatomical Structure ◽  
Thin Walled ◽  
Polyhedral Cells ◽  
A New Species

Four permineralized vitaceous seeds are described from the Middle Eocene Princeton chert, Allenby Formation, British Columbia. Three distinct types of ruminate perchalazal seeds are recognized, one is described as a new species Ampelocissus similkameenensis Cevallos-Ferriz et Stockey sp.nov., while the remaining seeds are referred to as type 1 and type 2 seeds. Five integumentary zones are recognized in each seed: zone 1 is an outer zone of thin-walled rectangular to polyhedral cells; zone 2 is a zone of thick-walled sclereids; zone 3 is a zone of cells with spiral thickenings; zone 4 is a zone of rectangular thin-walled cells (when preserved); and zone 5 is a zone of tangentially elongated thin-walled cells with dark contents. The chalaza in seeds of A. similkameenensis and the type 1 seed has three distinct zones, while in the type 2 seed it contains cells similar to integumentary zone 2. These Princeton seeds illustrate that structural features of Eocene Vitaceae include characters unlike those of extant taxa. This information contributes to our knowledge of anatomical structure within the group as a whole and underscores the need for review of both fossil and extant Vitaceae. Paucity of vitaceous seeds in the Princeton chert compared to the large number of preserved aquatic and semiaquatic remains suggests that they represent plants that grew in a nearby environment. Abrasion of the integument suggests that like extant seeds, they may have been dropped after passing through the gut of a bird.

Mechanical and photosynthetic constraints on the evolution of plant shape

Paleobiology ◽  
1984 ◽  
Vol 10 (1) ◽  
pp. 79-101 ◽  
Author(s):  
Karl J. Niklas ◽  
Vincent Kerchner
Keyword(s):  
Photosynthetic Efficiency ◽  
Growth Habit ◽  
Three Dimensional ◽  
Main Axis ◽  
Moment Arm ◽  
Total Moment ◽  
Moment Arms ◽  
Branching Patterns ◽  
Upper Silurian ◽  
Lateral Branches

A computer model is presented which is capable of calculating both the photosynthetic efficiency (I) of any specified plant shape and the stress related to the total moment arm (M) imposed on vertical branching patterns. Computer simulations indicate that a flattened plant thallus and an erect branching growth habit are two plant shapes capable of optimizing photosynthetic efficiency during indeterminate growth. These two morphologies have geometric analogues in the dorsiventral thalli of some bryophytes and in the vertical axes of mosses and tracheophytes, respectively.Extension of the model to complex, three-dimensional branching patterns indicates that I and I/M are maximized when branching is overtopped (treelike, with lateral branches on a main axis) and when lateral branching systems are planated (frondlike). Geometric alterations of branching patterns that result in optimization of I and I/M can be simulated by computer and are shown to be similar to morphologic alterations attending the early evolution of vascular land plants. It is suggested that a number of major evolutionary trends seen in Upper Silurian to Upper Devonian times can be expressed in terms of optimizing the display of photosynthetic tissues (I) or the balance between photosynthetic efficiency and incurred moment arms (I/M).

The structure of the antennal heart of Aedes aegypti (Linnaeus)

1997 ◽  
Vol 75 (3) ◽  
pp. 444-458 ◽  
Author(s):  
B. D. Sun ◽  
J. M. Schmidt
Keyword(s):  
Electron Microscopy ◽  
Connective Tissue ◽  
Aedes Aegypti ◽  
Light And Electron Microscopy ◽  
Single Layer ◽  
Epidermal Cells ◽  
Muscle Fibres ◽  
Columnar Cells

The structure of the antennal heart of Aedes aegypti (L.) (Diptera: Culicidae) was observed using light and electron microscopy. The antennal heart consists of several distinct regions including a single layer of columnar cells, the chamber walls, the valve, the z-body, the muscle fibres, and the connective tissue filaments. The columnar cells are structurally similar to secretory and osmoregulatory cells. Features of tendinous epidermal cells typically involved in the attachment of muscles to the cuticle can be observed in various areas of the antennal heart when it is examined as a whole. A model describing the pumping mechanism of the antennal heart in A. aegypti is presented.

scholarly journals Anatomical structure of stem in the above- and underground portions of Rosa rugosa suckers

1999 ◽  
Vol 5 (1-2) ◽  
Author(s):  
R. Fouda
Keyword(s):  
Adventitious Roots ◽  
Anatomical Structure ◽  
Rosa Rugosa ◽  
Histological Studies ◽  
Cambial Zone ◽  
Phloem Fibers ◽  
One Year ◽  
Underground Stem

Comparitive histological studies were made on the underground and the aboveground stem parts of Rosa rugosa taken from one year old suckers. The underground stem parts were characterized with thicker primary cortex, phloem and pith, weaker phloem fibers, wider cambial zone, medullary rays, xylem and phloem rays as compared with the aboveground stem parts. The most marked differences in the underground stem parts were in the wide cambial zone and in the development of some adventitious roots.  

Xylary union between elongating lateral branches and the main stem in Populus deltoides

1983 ◽  
Vol 61 (4) ◽  
pp. 1040-1051 ◽  
Author(s):  
Philip R. Larson ◽  
David G. Fisher
Keyword(s):  
Populus Deltoides ◽  
Secondary Xylem ◽  
Cambial Activity ◽  
Main Axis ◽  
Main Stem ◽  
Leaf Trace ◽  
Primary Xylem ◽  
Lateral Bud ◽  
Lateral Branches ◽  
Secondary Vessels

The vasculature of elongating lateral branches was examined to determine how vessels produced in the branch unite with those produced in the main stem axis to form a continuous transport system. In a previous study it was found that differentiation of both primary and secondary xylem in a lateral bud or branch is independent of that in the main axis; i.e., xylem does not differentiate into the bud or branch from the main axis. When serial sections of the nodal region are followed downward, the bud vascular cylinder merges with that of the main axis and the adaxially situated bud traces (those nearest the stem) enter the bud gap margin first. The primary vessels of these bud traces differentiate in an oblique downward path along the margins of the bud gap, and they form radial files of primary vessels that lie adjacent to primary xylem of leaf traces in the stem. Traces situated more abaxially in the bud (those farther from the stem) contribute to other radial files of primary vessels, each of which lies progressively closer to the bud gap. Secondary xylem is initiated in the stem before it is in the branch. Consequently, the last-formed metaxylem vessels of the bud traces are continuous with secondary vessels of the stem. These latter vessels lie in the stem secondary xylem immediately external to primary xylem from the bud. Secondary xylem in the branch is initiated when foliage leaves and internodes mature. Secondary vessels formed in the branch traces are continuous with secondary vessels in the stem; these vessels are embedded in a matrix of fibers. Because cambial activity is more vigorous in the stem than in the branch, two vessels that are radially adjacent in the branch may be widely separated by fibers in the stem. The central trace of the axillant leaf enters the gap immediately below the last branch traces; at this level in the stem the leaf trace vasculature is entirely primary. The stem secondary xylem that overlies the leaf trace is continuous with that in the axillary branch.

New occurrences of trimerophytes from the Devonian of eastern Canada

1978 ◽  
Vol 56 (24) ◽  
pp. 3052-3068 ◽  
Author(s):  
Jeffrey B. Doran ◽  
Patricia G. Gensel ◽  
Henry N. Andrews
Keyword(s):  
Middle Devonian ◽  
Early Stage ◽  
Lateral Branch ◽  
Main Axis ◽  
Eastern Canada ◽  
Morphologic Variation ◽  
Lateral Branches ◽  
Branch Type ◽  
Established Species ◽  
New Occurrences

Pertica dalhousii n.sp. is described from the late Lower or early Middle Devonian of New Brunswick. The plant is known from a central axis with spirally arranged, mostly dichotomous lateral branches. Some lateral branches terminate in erect clusters of 32–128 fusiform sporangia. Spores are circular, trilete, with a detachable outer sculptured layer, and resemble the dispersed spore genus Apiculiretusispora Streel. A trimerophyte from Gaspé is described and provisionally designated as cf. Pertica sp.; the specimens are too incompletely preserved to be assigned to any established species, but they add further information about morphologic variation in the genus Pertica.With the addition of new plant types referable to the trimerophytes, distinctions between genera and species are becoming less readily apparent, supporting the suggestion that the trimerophytes are a group of closely related plants in which considerable evolution was occurring in late Lower and Middle Devonian times. Additionally, these plants appear to represent an early stage in the differentiation of a distinct main axis – lateral branch type of organizaiton that probably led to the later evolution of megaphyllous leaves.

Melvillipteris quadriseriatagen. et sp. nov., a new plant assigned to Rhacophytales from the Upper Devonian (Famennian) of Arctic Canada

2015 ◽  
Vol 153 (4) ◽  
pp. 601-617 ◽  
Author(s):  
JIN-ZHUANG XUE ◽  
JAMES F. BASINGER
Keyword(s):  
Adventitious Roots ◽  
Canadian Arctic ◽  
Second Order ◽  
Upper Devonian ◽  
Late Devonian ◽  
Canadian Arctic Archipelago ◽  
Branching Pattern ◽  
First Order ◽  
Branching System ◽  
Lateral Branches

AbstractA new plant of Late Devonian (Famennian) age,Melvillipteris quadriseriatagen. et sp. nov., is reported from Melville Island, Nunavut, Canadian Arctic Archipelago. Main axes and two orders of lateral branches are recognized. The main axes are monopodial in habit, with a zigzag and/or upright appearance and dense adventitious roots attached on some internodes. First-order branches are inserted on the main axes in distichous pairs, showing a quadriseriate pattern (i.e. alternate pairs); they bear one or two sterile ultimate appendages on the proximal portions, and then distally bear alternate second-order branches. Second-order branches bear alternate ultimate appendages which may be fertile or sterile; the sterile ultimate appendages are composed of one or two successive dichotomies, terminating in oppositely recurved tips, and fertile appendages show an elaborate branching system. Each fertile appendage has an initial dichotomy forming two sister branches, each of which further divides three or four times to produce ultimate divisions terminated by sporangia. Two to four small fusiform sporangia are grouped in a truss which is supplied by penultimate division of the fertile appendage. The sporangia have a pointed tip and a longitudinal dehiscence. This new plant resembles other plants with a quadriseriate branching pattern (e.g.RhacophytonCrépin,CephalopterisNathorst,ProtocephalopterisAnaniev,EllesmerisHill, Scheckler & Basinger andProtopteridophytonLi & Hsü), and is assigned to the Rhacophytales. Its similarity to and divergence from the rhacophytaleans, cladoxylopsids and other related plants are discussed.

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