CALAMOCARPON INSIGNIS,A NEW GENUS OF HETEROSPOROUS,PETRIFIED CALAMITEAN CONES FROM THE AMERICAN CARBONIFEROUS

Baxter , R. W. (U. Kansas, Lawrence.) Calamocarpon insignis , a new genus of heterosporous, petrified calamitean cones from the American Carboniferous. Amer. Jour. Bot. 50(5): 469–476. Illus. 1963.—Calamocarpon insignis is described as a new genus of calamitean cone based on numerous fragments of microsporangiate and megasporangiate cones found in coal balls of middle Pennsylvanian age from the Cherokee Group of Kansas and the Des Moines Series of Iowa. The cones are similar to Calamostachys in general construction, having a hollow pith, prominent protoxylem canals, and alternating whorls of sterile bracts and sporangiophores. They differ in that the microsporangiate cones bear microsporangia each containing several hundred microspores which may occur as tetrads or single spores, while the megasporangiate cones bear large rectangular megasporangia each containing a single functional megaspore surrounded by sterile nutritive tissue. The microspores average 30–40μ in diameter compared to a maximum measurement of 2.7 × 0.7 mm for the single rectangular megaspore. The female gametophyte was produced within the megaspore which was held within the megasporangium during the entire period of development. The megasporangia were deciduous so that the entire structure was shed as a unit.     

ACAULANGIUM GEN. N., A FERTILE MARATTIALEAN FROM THE UPPER PENNSYLVANIAN OF ILLINOIS

Material described by Graham as Cyathotrachus bulbaceus is believed to represent a new genus that is a common constituent of Upper Pennsylvanian coal balls. The sessile synangia of Acaulangium gen. n. are borne in a row on either side of the pinnule midrib and are composed of four to six short, tapering, laterally appressed sporangia. The sporangia have extended tips which curve over the inside of the synangium distally and delimit a small open area inside the synangium. The outer facing walls of the sporangia are two to three cells thick throughout while the inner facing walls are uniseriate. During dehiscence the sporangia separate laterally and spore release results from the rupture of a row of elongate cells along the inner sporangium midline. Among species of Scolecopteris the new genus resembles S. illinoensis and S. minor var. parvifolia but differs in its sessile synangial attachment. The additional parenchyma present between sporangial cavities in the synangia of Acaulangium, and the tendency toward bilateral symmetry suggests an early stage in the evolution of a bivalve synangium such as is present in Marattia.     

SULLITHECA DACTYLIFERA GEN. ET SP. N.: A NEW MEDULLOSAN POLLEN ORGAN AND ITS EVOLUTIONARY SIGNIFICANCE

The pteridosperm (Medullosaceae) pollen organ Sullitheca dactylifera gen. et sp. n. is described from middle Pennsylvanian coal balls. The proximally fused units of the obpyriform compound synangium separate and extend distally as finger-like projections. Each projection contains 4–6 vertically oriented cylindrical sporangia arranged in pairs along the radius of the unit; each unit extends from the outer cover wall toward the center. The distal portion of the compound synangium is hollow as a result of the lateral separation of the centripetally and distally directed synangial units. About 40 tubular sporangia are present in all and dehiscence occurs along a lateral slit in each sporangium. Vascular strands are disposed around the periphery of the organ in addition to a single strand paralleling each sporangium. Two- or three-cell trichomes and stomata are present on the organ surface. Pollen of the Monoletes type is present. A paired row of sporangia in Sullitheca composing a synangial unit is considered the homologue of a paired row of sporangia in the more compact and highly evolved genus, Dolerotheca.     

Frenelopsis alata and its microsporangiate and ovuliferous reproductive structures from the Cenomanian of Bohemia (Czech Republic, Central Europe)

The conifer, Frenelopsis alata (K. Feistmantel) E. Knobloch (Cheirolepidiaceae), occurring mostly in the Cenomanian of Europe, is revised on the basis of the type material. Its comparison with relevant species of Frenelopsis is discussed.The ovuliferous cone associated with the genus Frenelopsis is recorded for the first time. For the associated ovuliferous cones of Frenelopsis, a new genus, Alvinia, is introduced in a new combination for the type: Alvinia bohemica (Velenovsky) comb. n. Its association with Frenelopsis alata is based on the presence of Classopollis pollen adhering to ovuliferous cone scales, and the same type of pollen found in the microsporangiate cone of F. alata, the same cuticle pattern present on ovuliferous cones, sterile twigs and microsporangiate cones of F. alata, and also the co-occurrence of ovuliferous cones or their scales and sterile twigs of F. alata.Large ovuliferous cones of Alvinia bohemica are formed by helically arranged ovuliferous scales subtended by bracts. Each ovuliferous cone scale displays one or two seeds covered by a covering flap, and three appendages, which form distally a funnel-like structure lined in its inner part by long trichomes. Numerous pollen grains of Classopollis adhere to the trichomes, and the structure is considered to function as a protostigmatic area.The ovuliferous cones of Alvinia differ from similar cones of the Cheirolepidiaceae, Hirmeriella and Tomaxellia, mainly in a high state of unification of the ovuliferous cone scale, reduction of appendages and in a presence of the protostigmatic funnel-like structure.The ovuliferous cones, Alvinia bohemica, rarely occur intact, so it is assumed that they disintegrate when mature. It seems likely that they were not woody. This assumption is supported by the flattened appearance of cones and their cone scales in the sediment, their flexibility and the absence of massive coaly matter known from cones of the Taxodiaceae and Cupressaceae. It is proposed that this type of ovuliferous cone scale indicates a specialized type of pollination. In addition, it is suggested that cone scales enclosing seeds play an important role in propagation.     

IDANOTHEKION GEN. N., A SYNANGIATE POLLEN ORGAN WITH SACCATE POLLEN FROM THE MIDDLE PENNSYLVANIAN OF ILLINOIS

Idanothekion glandulosum gen. et sp. n. is a synangiate pollen organ represented by approximately 30 specimens contained in coal balls from the middle Pennsylvanian of Illinois. Each synangium is composed of seven to nine elongate sporangia that are fused laterally for approximately four-fifths of their length, and are radially arranged about, and fused to, a short central column; the central column is restricted to the proximal one-third of the synangium. Distal to the column the sporangia surround a hollow central area. Dehiscence occurred by means of a longitudinal slit along the mid-line of the inner face of each sporangium. The outer walls of the sporangia have a complex histology involving an external epidermis, a middle presumably glandular layer containing scattered enlarged cells, and an inner layer made up of thin-walled parenchyma. Vascular tissue is present in the central column and outer walls of the sporangia. Each sporangium has a prominent, attenuate, multicellular tip. Large numbers of saccate pollen grains similar to those found in numerous fossil and extant coniferophytes as well as some Mesozoic pter-idosperms were produced in each sporangium. Idanolhekion resembles some synangia assignable to Paleozoic members of the Marattiales; however, the new genus compares most closely with pollen organs believed to have been produced by members of the Pteridospermales. It seems most likely that Idanothekion represents the pollen organ of some member of the Lyginopteridaceae that produced pollen of a type which up to now has not been known from Paleozoic seed ferns.     

THE SYNANGIATE NATURE OF DOLEROTHECA

Transverse sections through the distal region of a Dolerotheca specimen in a coal ball from the Calhoun coal of Illinois show the double rows of sporangia where they are free from one another. This leads to the conclusion that the sporangial rows should be regarded as extending inward from the campanulum cover rather than radiating outward from the center. This observation suggests that Dolerotheca is a synangium composed of many sporangial units of different lengths.     

北京萤火虫复眼的光学成像*

本文利用光学成像方法,研究了不同适应状态下的北京萤火虫phrococelia Pekininsis复眼所成的光学重叠像以及复眼的视场角。不同适应状态的晶体柱都能在距离复眼表面300-350μm之处形成光学重叠像。经过暗适应的晶体柱可以对不同物距的目标形成清晰的正重叠像,像的大小随物距的增大而减小;经明适应的晶体柱,成像物距范围变小,重叠像的像面亮度降低;经过漂白处理的晶体柱只能对一定的物距成像,像面亮度最低。 不同数目的晶体柱都能形成一重叠像,并随着其数目的增加,像面亮度也逐渐增强。根据对局部复眼视场范围的观察和其结构特征的了解,认为萤火虫单个复眼的视场角大于180度。     

INVESTIGATIONS OF NORTH AMERICAN CYCADEOIDS: POLLINATION MECHANISMS IN CYCADEOIDEA

Wind was at first thought of as the chief pollinating mechanism in Cycadeoidea because of the open angiosperm-flower-like reconstruction of the cone presented by G. R. Wieland in 1906. Selfing seemed a more likely possibility after Delevoryas reinterpreted the cone as a closed structure in 1963. However, the existence of what was considered to be a dioecious group of species made it impossible to consider selfing as ubiquitous throughout the cycadeoids. Furthermore, only ovule-bearing trunks of the species considered to be dioecious were known; no corresponding trunks bearing exclusively microsporangiate cones had ever been found. Recent investigations of a trunk of the type heretofore considered as representative of the dioecious species have revealed that these cones were actually bisporangiate. The discovery that the bisporangiate condition was normal in the cycadeoids eliminates much of the confusion in understanding the system of pollination and allows selfing to be considered the chief means of pollination. Outcrossing probably occurred in very low frequency and could have been the result of a chance wind pollination or of a set of interactions between the cycadeoids and an unidentified animal. Determining the nature of the system of pollination in the cycadeoids makes it possible to speculate on the population structure and evolutionary potential of this important Mesozoic group of plants.     

Una nueva especie de Weltrichia (Bennettitales) del Jurásico Medio de la Formación Tecomazuchil (Oaxaca, México)

A new species of Weltrichia (Williamsoniaceae: Bennettitales) is described from the Middle Jurassic of Oaxaca. The specimens come from the Tecomazuchil Formation in the Ayuquila region, at the border between the Oaxaca and Puebla states. Fossils are preserved as impressions and compressions, in a fine-grained sublitharenite sequence deposited in a fluvial environment. Preserved diagnostic characters include: large size; a cup-shaped receptacle showing seven radially arranged and basically fused microsporophylls bearing synangia. Microsporophylls are ornamented with longitudinal striations and fine brittled hairs on the edge of their wide base, and taper into a narrow distal tip. In the adaxial part of the microsporophylls seven to nine synangia are observed. These characters differentiate the new species Weltrichia mixtequensis from all previously recorded species from Mexico or elsewhere. The presence of this new species in the Middle Jurassic strata of the Ayuquila region add to the scarce fossil record of microsporangiate structures in the Jurassic flora of Mexico.     

FERAXOTHECA GEN. N., A LYGINOPTERID POLLEN ORGAN FROM THE PENNSYLVANIAN OF NORTH AMERICA

The pollen organ Feraxotheca gen. n. is described from Pennsylvanian age coal balls from the Lewis Creek, Kentucky, locality. The fructifications consist of bilaterally symmetrical synangia composed of a basal pad supporting elongate sporangia that are laterally appressed for the entire length of the sporangial cavities. Sporangial tips extend over the center of the synangium and delimit a small open area, while the bases arise from a parenchymatous cushion that is bounded by short tracheid-like cells. Each synangium is borne on the surface of an expanded pinna tip and is surrounded by a small amount of laminar tissue that envelopes the base of the synangium. Ultimate pinnae are rectangular in transverse section, possess an elliptical vascular bundle surrounded by canals containing a yellow froth-like substance, and have a cortex of elongate cells that radiate from the center of the axis. Sporangia contain small (40–64 μm), radial, trilete spores ornamented by regularly spaced coni or blunt tipped grana. Feraxotheca is compared with the compression genus Crossotheca and some new ideas are advanced concerning the morphology of this compression genus. The obvious differences between Feraxotheca and other lyginopterid pollen organs strongly suggests that the Lyginopteridaceae, as it is currently interpreted, is an unnatural family.     

ON PHENOTYPIC EXPRESSION,MORPHOGENETIC PATTERN AND SYNANGIUM EVOLUTION IN PSILOTUM

Both the typical form and the appendageless variant of Psilotum nudum produce terminal synangia at the ultimate tips of the aerial axes. One clone in particular of the typical appendaged form produced synangia entirely at the tips of the aerial branches, as in the appendageless variant, and also developed occasional lateral transitional entities on the upper aerial axis displaying appendagelike and axislike morphological qualities. A developmental comparison of synangium development at the ultimate tips of aerial branches and of unusually elongating and normal sized fertile-appendages showed that the morphogenetic pattern of synangium development was similar. Anatomical and morphological evidence showed the synangium to be derived from terminal subdivisions or bifurcations of the apical meristem of each structure studied. This supports the phyletic concept that the synangium of the Psilotaceae is basically terminal to an axis or an axis homologue, and that it probably evolved from terminal bifurcative branching. Occasional multiple sporangium lobes may be formed on a P. nudum synangium which may not be represented by vascular bundles. Two hypothetical phyletic models of synangium evolution are proposed that could be used to explain this phenomenon and which should be tested by further evidence. Typical and appendageless P. nudum were compared in their morphogenetic pattern developed at the upper axis vegetative apical meristem, and a reconciliation was made between the structuring of the apparently disparate forms, which involved the presence or absence of serial ordering in apical derivatives. It is suggested that this could serve as a model for appendage evolution in the family Psilotaceae.     

Pollen Organs and Seeds with Decussosporites Brenner from Lower Cretaceous Potomac Group Sediments of Eastern USA

Microsporangiate structures, Brenneria potomacensis gen. et sp. nov., containing pollen grains similar to dispersed Decussosporites are described from the Lower Cretaceous (Barremian or Early Aptian?) Potomac Group localities at Drewry's Bluff and Dutch Gap on the James River southeast of Richmond, Virginia. These fossils provide the first megafossil evidence of plants producing Decussosporites-type pollen and contribute important new information on the structure and possible systematic affinities of this unique Mesozoic gymnosperm. The microsporangiate structure is composed of an axis with helically arranged synangiate microsporangiate units, each unit consisting of two laterally fused sporangia borne on a short stalk. The pollen grains are very small, bisaccate, distinctly striate (taeniate) and TEM shows that they have partly infilled sacci (quasisaccate). These grains represent the youngest occurrence of saccate, striate pollen, which has not been recorded previously from sediments younger than the earliest Jurassic. Fossil seeds (Brennerispermum potomacensis gen. et sp. nov.) from the same localities as Brenneria contain Decussosporites pollen in the micropyle, and are believed to have been produced by the same plant species. The seeds are small and unitegmic with a distinct megaspore membrane. The occurrence of seeds adhering together in groups indicates that they were borne in aggregations. The microsporangiate structures of Brenneria show some similarity to those of the ginkgophytes (Ginkgoales and Czekanowskiales), but there are substantial differences in the structure of seeds and pollen. The Decussosporites pollen grains together with morphology of the reproductive organs support a closer relationship of the Brenneria-plant to previously described “Mesozoic pteridosperms”.     

A re-examination of Lepidostrobus Brongniart

Lepidostrobus is a genus that was established by Brongniart for Palaeozoic lycopod cones. Since then the genus has been used for a variety of cones that have similar characters. There is now compelling evidence that the genus represents a heterogeneous group of monosporangiate and bisporangiate cone species and that it should be divided. Lepidostrobus is rediagnosed as a genus of microsporangiate cones. Ftemingites Carruthers is rediagnosed as a genus of those bisporangiate cones formerly included in Lepidostrobus.     

THE MORPHOLOGY AND RELATIONSHIPS OF RHODEA,TELANGIUM, TELANGIOPSIS,AND HETERANGIUM

This study deals with four form or organ genera from the Upper Mississippian (Chester Series) of the Illinois Basin, and provides evidence that they were produced by a single natural genus with gymnospermous affinity. The plant remains—compressions, impressions, petrifactions, and specimens that combine compression or impression with petrifaction—allow examination of both external morphology and internal anatomy. The specimens include foliage corresponding to Rhodea, stems and petioles corresponding to Heterangium, and synangiate fructifications corresponding to either Telangium or Telangiopsis. The stems and foliage are considered parts of the same plant because of the identity of the anatomical and cuticular features of petioles attached to stem and those petioles with attached foliage. The fertile material is regarded as part of the same plant because: (1) The anatomy of axes of the fertile specimens is like that of the sterile specimens. (2) A single specimen may contain both sterile Rhodea-type axes and fertile regions. (3) Axes bearing synangia have the same size and patterns of divisions as the sterile foliage. Features that indicate lyginopterid affinities include: (1) Equal forking of the petiole. (2) Presence of fiber bands in the outer cortex and sclerotic nests in the inner part of the cortex. (3) Crowded circular bordered pits on the lateral walls of the metaxylem tracheids. (4) The presence of a small amount of secondary xylem. A variety of structural details of the stem and petiole suggest the genus Heterangium. The phyletic position of the plant that produced Rhodea, Telangium, Telangiopsis, and Heterangium is reviewed in light of such discoveries as the presence of a planated frond that lacks a lamina and the presence of both monolete and trilete microspores in a single synangium.     

Immunocytochemical demonstration of taurine in the retina and pineal organof the pigeon

Taurine-like immunoreactivity (TLI) is found in the pigeon retina at high levels within cones, in select cells of the inner nuclear layer and in sublaminae of the inner plexiform layer. At the ultrastructural level a high density of immuno-gold particles is visualized in the ellipsoid, but not in the paraboloid area of the inner segment. It is present in perikarya and the presynaptic endings of cones, but not in postsynaptic cell processes. The immuno-gold particles are not associated directly with the synaptic vesicles. In the pineal organ TLI was confined to the so-called dark pinealocytes which are surrounded by only faintly stained light pinealocytes. Clusters of protein A-gold particles are located in the ergastoplasm between polyribosomes adjacent to fibrous proteins and in chains along filamentous structures. Granules, vesicles and membrane whorls, which originate from modified cilia remain unlabeled. The results are discussed on the basis of previous findings; a direct or indirect functional relationship of taurine to ATP-dependent processes is suggested.     

Ontogeny of the photoreceptors in the embryonic retina of the viviparous guppy,Poecilia reticulata P. (Teleostei)

Summary Ultrastructural analyses of retinal development in the guppy embryo show that at midgestation all types of photoreceptors are differntiated in the fundus, and at birth differentiation extends over the whole retina. Formation of discs of outer segments is more rapid in rods than in cones. Double cones differentiate simultaneously with long single cones and are formed by the adhesion of two primordial inner segments; short single cones develop last. Wherever cones are differentiated, they are arranged in an adult-type square mosaic. The rods in the embryo, as opposed to the adult, are likewise regularly arranged within the mosaic unit.These results are at variance with the generally held opinion that adult teleosts which possess duplex retinae have larvae with pure cone retinae, and that rods, double cones and mosaics appear in late larval life or only at metamorphosis.In the double cones of the guppy embryo subsurface cisternae develop along the adjoining primordial inner segments. Additionally, regularly distributed subsurface cisternae are formed in the regions of intimate contact of long single cones with double cones and rods.We suggest that the early development of rods and double cones, and a square-mosaic with regular distribution of rods and subsurface cisternae, provide the newly born with a fully functional optical apparatus, especially suited to perception of movements. This is necessary for its survival against predatory, especially maternal, attacks.This work was in part subsidized by a grant from the Medical Research Council of Ireland to Y.W.K.     

A pre-embedding immunogold approach reveals localization of myosin VI at the ultrastructural level in the actin cones that mediate <Emphasis Type="Italic">Drosophila</Emphasis> spermatid individualization

Stable actin structures play important roles in the development and specialization of differentiated cells. How these structures form, are organized, and are used to mediate physiological processes is not well understood in most cases. In Drosophila testis, stable actin structures, called actin cones, mediate spermatid individualization, a large-scale cellular remodeling process. These actin cones are composed of two structural domains, a front meshwork and a rear region of parallel bundles. Myosin VI is an important player in proper actin cone organization and function. Myosin VI localizes to the cones' fronts and its specific localization is required for proper actin cone formation and function during individualization. To understand how these structures are organized and assembled, ultrastructural studies are important to reveal both organization of actin and the precise localization of actin regulators relative to regions with different filament organizations. In the present work, we have developed a novel pre-embedding immunogold-silver labeling method for high-resolution analysis of protein distribution in actin structures which allowed both satisfactory antibody labeling and good ultrastructural preservation. Electron microscopic studies revealed that myosin VI accumulated at the extreme leading edge of the actin cone and preferentially localized throughout the front meshwork of the cone where branched actin filaments were most concentrated. No myosin VI labeling was found adjacent to the membranes along the length of the cone or connecting neighboring cones. This method has potential to reveal important information about precise relationships between actin-binding proteins, membranes, and different types of actin structures.     

PALEOZOIC LYCOPSID FRUCTIFICATIONS. III. CONSPECIFICITY OF BRITISH AND NORTH AMERICAN LEPIDOSTROBUS PETRIFACTIONS

A study was made of 30 apparently similar microsporangiate cone specimens of the lycopsid fructification Lepidostrobus found in coal balls of Middle Pennsylvanian age from Illinois and Kansas. None of these specimens was a complete cone, but at least 19 were large enough and well enough preserved to provide information regarding variation both within one cone and among several specimens. The data obtained substantiated the original assumption that all 30 specimens represented one species. Attempts to equate this one species with any of the similar, previously described North American taxa, Lepidostrobus coulteri, L. pulvinatus and Lepidocarpon magnificum-microsporangiate form, and the British taxon Lepidostrobus oldhamius, including the forms (α), (β), (γ) and pilosus, revealed that no significant differences existed among any of these taxa. Furthermore, all characteristics described for these taxa were referable to, and well within the range of variation of, the one species here analyzed. Differences among the taxa were found to represent only differences in maturation or normal variation. All these taxa are, therefore, conspecific and are assigned to one species which by priority is named Lepidostrobus oldhamius. The common association of the megasporangiate Lepidocarpon lomaxi with all these miorosporangiate cones, now recognized as representing the single taxon Lepidostrobus oldhamius, is strong evidence for the probability that Lepidocarpon lomaxi and Lepidostrobus oldhamius were produced by the same parent plant species.     

Melissiotheca: a new pteridosperm pollen organ from the Lower Carboniferous of Scotland

Melissiotheca is based on fusainized pollen organs of pteridospermous affinities which occur abundantly in an Upper Visean limestone at Kingswood, near Pettycur (Scotland). The new species is a pedicellate synangium composed of 50–150 sporangia each of which is embedded at its base in a parenchymatous cushion divided into lobes. The sporangia are fused along their proximal half but are free distally. Dehiscence is longitudinal. Each sporangium is supplied at its base by a single vascular strand. Prepollen is small, spherical and trilete with a rugulate exine. In ultrastructure, the nexine appears homogeneous; the sexine shows internal sculpture of granae and rod elements. Melissiotheca has not been assigned to any family, but it shows many affinities with pollen organs attributed to the Lyginopteridaceae.     

Patch dynamics and local succession in a sandstone area with frequent disturbance

Abstract. A system of sand talus cones in a small forested rocky sandstone area was investigated to determine the importance of disturbance‐related dynamics and mesoclimate to vegetation differentiation. These cones (usually 3–12 m long) are formed by the accumulation of sand at the foot of sandstone rocks and are subject to frequent disturbance by the transport of sand. Vegetation was recorded both at the whole‐cone level and at the within‐cone level; the latter was approached by means of a transect of small squares along each cone. Soil profiles were recorded at the upper, centre and bottom parts of the cones. To express mesoclimatic differentiation among the cones within the rocky area, the potential insolation was calculated from the horizon angular height and the likelihood of thermal inversions was estimated by the height of the cones above the valley bottom. The major environmental factor correlated with variation in cone vegetation is the disturbance dynamics as determined by the structure of the soil profile; active cones (with sand at the surface) are colonized by different species as compared with non‐active cones (with surface covered by humus sediments). There is a clear primary succession gradient from plants able to cope with continuous sand transport to stands of tall bryophytes, small shrubs and herbs. Quite often the same gradient is found within cones, with late successional vegetation confined to the lower, stabilized parts of the cones, while the upper part is still being affected by sand transport. The differentiation along the gradient of disturbance is much stronger than the differentiation due to climatic or other gradients. Indirect data indicate that the long‐term average rate of sand accumulation is ca. 1 mm/yr. If sand transport ceases, Sphagnum peat accumulates on some of the cones; the depth of accumulated Sphagnum remains may reach 50 cm. The development of the peat layer is but weakly correlated with the measured variables suggesting that random processes at the beginning of Sphagnum establishment may be a driving force. By measuring Sphagnum growth and decomposition, and the peat density, we estimated the time needed for their development to be several hundreds of years.