Heterogeneous Pith Research Articles

A new species of Keteleeria (Pinaceae) from the Lower Cretaceous of Inner Mongolia, Northeast China, and its palaeogeographic and palaeoclimatic implications

Keteleeria Carrière (Pinaceae) is a small genus of evergreen conifer trees, with three to five extant species and six variants distributed across China, Laos, and Vietnam. A new species of conifer fossil wood, Keteleeria huolinhensis sp. nov., is described from the Lower Cretaceous Huolinhe Formation in Inner Mongolia, China. This species is characterized by a heterogeneous pith, endarch primary xylem, the presence of axial resin canals, abietinean radial tracheid pitting, mostly taxodioid and occasionally cupressoid cross-field pitting, nodular horizontal and end walls of ray parenchyma cells, and uniseriate rays of 1–15 (mainly 1–8) cell height. This newly discovered fossil wood represents the earliest record of Keteleeria wood, and sheds light on its evolutionary history and palaeogeographical distribution ranges in the geological past. Cladistic analysis based on 12 morphological characteristics supports the assignment of Protopiceoxylon as the ancestral group of Keteleerioxylon and Keteleeria, reflecting the evolution of radial tracheid pitting from the mixed to abietinean type. Quantitative analysis of the growth rings indicated that K. huolinhensis sp. nov. is an evergreen tree with a Leaf Retention Time (LRT) of 1–3 years. The growth ring patterns in the present fossil wood specimen suggest that the Huolinhe Basin experienced a temperate climate with regular seasonal fluctuations, and relatively sufficient water supply during the Early Cretaceous. Traumatic resin canals, wound scars, presumed fungal remains, and insect tracks in the stem contribute to a further understanding of the complex ecological relationships in the Early Cretaceous Huolinhe flora.

A new structurally preserved fossil umbrella pine from the Jurassic of East Asia

The Sciadopityaceae are today a monotypic and relict family of the Coniferales, restricted to Japan with an endemic species of Sciadopitys verticillata Sieb. et Zucc., known as umbrella pine. Megafossil remains assigned to the Sciadopityaceae have been reported from various parts of the boreal hemisphere. However, structurally preserved fossil wood of the Sciadopityaceae is poorly documented. Here we present an anatomically preserved fossil wood of the Sciadopityaceae from the Jurassic of East Asia. A new fossil wood Zhangoxylon yanliaoense gen. et sp. nov. is proposed for the specimens, which are anatomically characterized by a heterogeneous pith, endarch primary xylem, and special secondary xylem. The anatomical structures of the new genus are similar to those of the living Sciadopitys except for the type of radial pitting. The present specimen has an araucarian radial pitting, while that of the living Sciadopitys is abietinean. Therefore, Zhangoxylon gen. nov. from the Middle to Late Jurassic (Callovian to Kimmeridgian) in western Liaoning may represent the Sciadopitys‐like petrified wood which bears pith and primary xylem. This new fossil, so far, the best‐known fossil wood of the family Sciadopityaceae, sheds light on the early evolutionary history of the family Sciadopityaceae, and contributes to a better understanding of the palaeoenvironment of the Jurassic Yanliao Biota in East Asia.

Cyathealean Antarctic ferns from the Aptian Cerro Negro Formation: Rafaherbstia nishidai gen. et sp. nov. and associated fertile organs

New remains corresponding to Cyathealean tree ferns are described for the Aptian Cerro Negro Formation at Byers Peninsula, Livingston Island (South Shetland Islands, Antarctica). A new genus and species, Rafaherbstia nishidai, is proposed for several permineralized dictyostelic stems characterized by a heterogeneous pith with a central star-shaped sclerenchyma mass, U-shaped meristeles developing small hooks at the margins of the leaf gap, sclerenchyma sheaths surrounding the vascular strands, and leaf traces omega-shaped and multi parted. The new taxon shows a combination of features that preclude its placement in one of the eight recognized families of Cyatheales, supporting that previous diversity of tree ferns was higher than in modern times. Fragmentary isolated sori with preserved sporangia containing trilete spores, recovered from the sedimentary matrix surrounding the stems, are also described. These new tree ferns increase the diversity of Cyatheales in the Cerro Negro Formation, and support warm climatic conditions in this region during the Aptian.

Permineralized osmundaceous and gleicheniaceous ferns from the Jurassic of Inner Mongolia, NE China

Structurally preserved fossil ferns are extremely significant for exploring the origin and evolution of this plant clade; however, they are quite scarce and limited in the Mesozoic. Here, we report some well-preserved fern rhizomes and rachides with anatomical details from the Upper Jurassic Manketouebo Formation in Inner Mongolia, NE China. Two taxa, including Ashicaulis liaoningensis (Zhang et Zheng) Tidwell referred to Osmundaceae and Gleicheniorachis sinensis sp. nov. referred to Gleicheniaceae, are recognized. Anatomically, Ashicaulis liaoningensis consists of a heterogeneous pith, an ectophloic dictyoxylic siphonostele, a two-layered cortex, C-shaped leaf traces, and a mantle of petiole bases. The petiole base is characterized by a heterogeneous sclerotic ring with an abaxial thick-walled fiber arc. Gleicheniorachis sinensis sp. nov. consists of a C-shaped vascular bundle with two incurved adaxial hooks, a distinct sclerenchyma sheath, an endodermis, and a heterogeneous cortex. In particular, the finding of Gleicheniorachis sinensis sp. nov. represents the first report of unequivocal Jurassic record of Gleicheniaceae in northern China, as well as the first record of a Jurassic permineralized gleicheniaceous fern in the Northern Hemisphere. This study provides new data and evidence for exploring the anatomical diversity and evolution of Mesozoic ferns, and contributes to further understanding the floral composition of Late Jurassic flora in Northeast China.

Turpanopitys taoshuyuanense gen. et sp. nov., a novel woody branch discovered in Early Triassic deposits of the Turpan Basin, Northwest China, and its palaeoecological and palaeoclimate implications

A novel well-preserved woody branch, Turpanopitys taoshuyuanense gen. et sp. nov. was collected in the early Triassic terrestrial deposits in the Turpan Basin, Northwest China. The permineralized wood is characterized by a heterogeneous pith, endarch primary xylem and Protophyllocladoxylon-type secondary xylem. The pith consists of parenchyma cells and supporting diaphragms formed by brick-like sclerenchyma cells. The quantitative growth-ring analyses of T. taoshuyuanense indicate that the species was evergreen, the leaf longevity being comprised between 3 and 15years. T. taoshuyuanense might indicate a warm humid climate with short dry periods in the Turpan basin in the Early Triassic. The Protophyllocladoxylon-type woods were widely distributed in different climate zone in both southern and northern hemispheres during the Palaeozoic and Early Triassic. The growth rings of the woods with Protophyllocladoxylon-type secondary xylem are good indicator for the palaeoclimate. The new specimen indicates that a warm humid climate with irregularly distributed short dry periods in the Early Triassic Turpan basin.

The Evolution of Violaceae from an Anatomical and Morphological Perspective1

Abstract Recent work suggests that Fusispermum Cuatrec. and Rinorea Aubl. form small clades that are sister to the rest of the Violaceae and that the Goupiaceae is sister to the Violaceae. However, little is known about the morphology and anatomy of these phylogenetically critical groups. In this paper I present aspects of the morphology and anatomy of stem, node, leaf, flower, and seed of three species of Fusispermum and seven species of Rinorea, as well as Goupia glabra Aubl. (Goupiaceae), which is the outgroup. Placing this variation in the context of hypothesized phylogenetic relationships, I found Fusispermum to have unique pentalacunar nodes, heterogeneous pith, and elongated seeds, while Goupia Aubl. has a unique 5-carpellate gynoecium with marginal styles and a tegmen with U-shaped thickenings. Furthermore, variation in androecium and nectary links the distinctive androecium so common in the Violaceae with more conventional structures found in other taxa of the parietal placentation group of Malpi...

Septomedullopitys szei sp. nov., a new gymnospermous wood from Lower Wuchiapingian (Upper Permian) continental deposits of NW China, and its implication for a weakly seasonal humid climate in mid-latitude NE Pangaea

Septomedullopitys szei sp. nov. is described from the Wuchiapingian Wutonggou Formation of Tarlong Valley, southern Bogda Mountains, Xinjiang, in northwestern China. The stem has a heterogeneous pith ca. 15–20mm in diameter, and containing numerous linear secretory ducts and parenchymatous bands. Primary xylem is endarch and the tracheids contain scalariform thickenings. Secondary xylem is of the Protophyllocladoxylon type. Comparisons with contemporaneous gymnospermous woods containing either heterogeneous pith with ducts or Protophyllocladoxylon-type secondary xylem from the Angara palaeocontinent indicate that the Tarlong stem represents a new Permian morphotaxon for the region. The presence of coprolites, borings, and spindle-shaped cavities within the stem suggests well-developed animal–plant–fungi interactions. The occurrence of numerous growth interruptions and absence of true growth rings within the stem suggest weak seasonality of annual precipitation. The interruptions suggest a humid climate with short-term, nonperiodic droughts.

A new structurally preserved fern rhizome of Osmundaceae (Filicales) Ashicaulis wangii sp. nov. from the Jurassic of western Liaoning and its significances for palaeobiogeography and evolution

Permineralized osmundaceous rhizome with anatomical and phylogenetic information plays a significant role in understanding the origin, evolution, and diversity variation of the fern family Osmundaceae in geological history. The northern Hebei and western Liaoning region is one of the most important fossil localities for the Jurassic osmundaceous rhizome fossils in the Northern Hemisphere; however, the diversity character of osmundaceous rhizome fossil remains poorly known. A new structurally preserved fern rhizome species, Ashicaulis wangii sp. nov., is described from the Middle Jurassic Tiaojishan Formation in Beipiao City, Liaoning Province, northeastern China. The rhizome is composed of heterogeneous pith, an ectophloic-dictyoxylic siphonostele, a two-layered cortex, and a mantle of adventitious roots and petiole bases. The xylem cylinder, with complete leaf gaps, consists of 15–17 xylem strands. The petiole base is characterized by a heterogeneous sclerotic ring and numerous sclerenchyma masses in the petiolar cortex. Among five known Ashicaulis species with heterogeneous sclerotic ring, four of them are documented from China. Therefore, osmundaceous rhizome fossils from China show endemic anatomical characteristics and significances for palaeobiogeography. Comparisons of anatomical features suggest that A. wangii sp. nov. bears close similarities to Osmunda pluma Miller from the Paleocene of Dakota, USA. Fossil species of A. wangii provides new evidence for further understanding the species diversity of osmundaceous rhizome fossil in China and in the Northern Hemisphere, and contributes to exploring the macroevolution process of the Mesozoic osmundaceous plants.

The anatomically preserved stem Zhongmingella gen. nov. from the Upper Permian of China: evaluating the early evolution and phylogeny of the Osmundales

Reinvestigation of the anatomically preserved stem Palaeosmunda plenasioides from the Lopingian (Late Permian) of China has led to the establishment of Zhongmingella gen. nov. within the extinct family Guaireaceae (Osmundales). Zhongmingella has a rhizomatous stem with heterogeneous pith and cortex comprising parenchyma and uniformly distributed secretory cells, and is dictyostelic. In order to evaluate the systematic and phylogenetic position of Zhongmingella within Guaireaceae, and Guaireaceae within Osmundales, we conducted a preliminary cladistic analysis of a broad range of Osmundales and related taxa based on 18 extinct and six extant genera and subgenera. Results do not support the traditionally defined family Thamnopteroideae (Bathypteris, Chasmatopteris, Iegosigopteris, Thamnopteris, Zalesskya) and demonstrate that Thamnopteroideae is not a subfamily of Osmundaceae as previously thought. Guaireaceae is monophyletic but in addition to its traditionally defined members (Guairea, Lunea, Donwellicaulis, Itopsidema, Shuichengella, Zhongmingella) includes the stratigraphically younger genus Osmundacaulis previously placed in Osmundaceae. Guaireaceae is sister to Osmundaceae, Millerocaulis, Ashicaulis, Palaeosmunda and Aurealcaulis in the strict consensus, but in the majority-rule consensus Palaeosmunda, Aurealcaulis, Ashicaulis and Millerocaulis form the Osmundaceae stem group, with (Aurealcaulis, (Ashicaulis + Palaeosmunda)) sister to the extant genera. Stratigraphical analysis of the selected most parsimonious tree demonstrates that Osmundales underwent primary radiation during the Pennsylvanian and Permian, terminating abruptly around the time of the end-Permian mass extinction. Radiation within Osmundaceae occurred in the Triassic–Cretaceous and stratigraphically overlaps staggered extinctions in Guaireaceae and Osmundaceae from the Late Jurassic to mid-Cretaceous alongside the earliest angiosperm radiation. Our results identify the Osmundaceae stem and sister groups for the first time, and represent an important step in unravelling the evolutionary history of Osmundales. However, reconstructed whole-plant species are imperative to improve understanding of the relationships within the clade in deep time.

Gymnosperm trees from the Permian of Antarctica: An anatomically preserved trunk of Kaokoxylon sp.

Anatomically preserved gymnosperm axes are relatively abundant in Permian localities of Antarctica, but their anatomy has rarely been studied in detail, which limits comparison with other Gondwanan morphotaxa. Here we describe a silicified trunk collected from the Upper Permian Buckley Formation at Coalsack Bluff, in the central Transantarctic Mountains. The trunk has a small heterogeneous pith approximately 4mm in diameter containing conspicuous sclerotic nests, endarch primary xylem maturation, paired leaf traces, and secondary xylem of the Araucarioxylon type. Comparison with contemporaneous gymnosperm axes from Antarctica indicates that the Coalsack Bluff trunk represents a new Permian morphotaxon for the region. The anatomical characters of the pith and secondary xylem suggest an affinity with the genus Kaokoxylon Kräusel, previously reported from Permian and Triassic localities of Southern Africa, South America, India, and Australia.

Occurrence of Sciadopitys-like fossil wood (Coniferales) in the Jurassic of western Liaoning and its evolutionary implications

The genus Sciadopitys, containing a single species (S. verticillata), is the only extant representative of the Family Sciadopityaceae (Coniferales), and is a remarkable living fossil. Although some leafy fossils have been ascribed to Sciadopityaceae, fossil xylem material with a close affinity to this family is very rare, and there have been no fossils found showing both pith and primary xylem structures, which are of great importance for wood identification. Thus, it has been difficult to use fossils for the understanding of wood anatomy evolution in the sciadopityaceous plants over geological time. In this note we briefly report on Sciadopitys-like fossil wood found in the Middle Jurassic of western Liaoning, which bears well-preserved Protosciadopityoxylon-type secondary xylem, endarch primary xylem and heterogeneous pith. This is the first report of fossil specimens of the Sciadopityaceae with such detailed preservation of wood structures. The discovery provides precise anatomical evidence for reconstructing the evolutionary history and geographical distribution of Sciadopityaceae, as well as contributing to understanding of the fossil diversity of the Jurassic Yanliao Flora in northern China.

A unique gymnosperm from the latest Permian of China, and its ecophysiological implications

A unique coniferous woody stem Shenoxylon mirabile gen. nov. et sp. nov. is described from the very late Late Permian Changhsingian (Lopingian) Sunjiagou Formation of the Shitanjing coalfield, northern China. The silicified decorticated stem is characterized by a complex pith in the broad (7 mm) eustelic vascular system, thick secondary xylem cylinder and helically arranged leaf traces. The heterogeneous pith consists of a densely arranged sclerified intramedullary sheath that separates the loosely arranged central parenchyma and peripheral sclerified cells into three prominent zones. The primary xylem strands show endarch maturation, the tracheids from the protoxylem to metaxylem showing annular to scalariform/reticulate thickenings. The secondary xylem is pycnoxylic; uniseriate bordered pits are continuous or individually spaced on the radial walls of tracheids, with partially biseriate, alternate or occasionally opposite; the cross-fields show one or two cupressoid pits; ray cells are parenchymatous with smooth walls; axial parenchyma is developed. Growth-rings are present and false rings are frequently developed throughout the secondary xylem; resin canals are absent. The leaf traces are composed of monarch vascular bundles and of circular to longitudinally elongate shape in cross section; they originate from the periphery of the pith and pass through the whole xylem cylinder nearly horizontally. The frequent occurrences of false rings are interpreted as ecophysiological responses of the plant to the environmental turbulences during the latest Permian terrestrial ecosystem.

Alienopteris livingstonensis gen. et sp. nov., enigmatic petrified tree fern stem (Cyatheales) from the Aptian Cerro Negro Formation, Antarctica

A new genus and species of Mesozoic fern, Alienopteris livingstonensis gen. et sp. nov., is defined, based on permineralized stems recovered from the Aptian Cerro Negro Formation (Antarctica). This new taxon is characterized by the presence of Y-shaped meristeles in the stem, surrounding an heterogeneous pith, and the presence of complex petiole bases, consisting in abaxial and adaxial archs, similar to the ones present in the Cyatheaceae s.l.. Since no living nor fossil filicalean fern possesses such mixture of features, and taking into account that no leaves and reproductive structures were found, phylogenetic relationships are not clear. Two independent cladistic analysis show clear placement of Alienopteris livingstonensis among the “core tree ferns.”

Rhexoxylon brunoi Artabe, Brea et Zamuner, sp. nov., a new Triassic corystosperm from the Paramillo de Uspallata, Mendoza, Argentina

A new species of Rhexoxylon from the Upper Triassic of Argentina is described. The material was collected at El Paramillo de Uspallata area and comes from Los Colorados Formation. There is a big buried specimen and scattered material which is preserved by silicification, corresponding to an adult eccentric, oval trunk, whose diameter is 71×58 cm. Three zones can be distinguished: pith, vascular (with perimedullar bundles and centrifugal wedges of secondary xylem) and cork layer. Rhexoxylon brunoi Artabe, Brea et Zamuner, sp. nov. has a heterogeneous pith with parenchyma cells and idioblasts. Perimedullar bundles make up two cycles; the first one is complete constituted by double collateral bundles, facing each other, with secondary growth. The second one is incomplete, showing just the centripetal xylem sector. Peripheral centrifugal secondary xylem wedges show extensive development, reaching up to 38 cm of thickness. The tracheids of secondary xylem have opposite uni- to biseriate bordered radial pitting, and crossfields with one or two simple, slanted lenticular pits. Outside of the xylem a cork layer of about 2 cm persists conforming a longitudinally and transversely fractured rhytidome-like zone. Rhexoxylon brunoi shows a morpho-structural pattern determined by high activity of normal cambium, moderate activity of supernumerary cambium and scarce activity of remanent cambium.

Sur un bois silicifiéà moelle conservée du Permien du Bassin de Tiddas (Maroc Central), Mesopityoxylon tiddasense gen. et sp. nov. — Intérêts phylogénetique et paléoclimatique

In the Lower Permian locality of Bou Rzem (Central Morroco), red pellite deposits have for the first time yielded a silicified wood with a well-preserved pith. This structure characterized by a typical secondary wood of “ Dadoxylon schrollianum” type and primary vascular structure has a heterogeneous pith with nests of sclerenchyma including vertical secretory canals. A transfusion tissue is placed inside the centrifugal primary xylem. The interpretation of this structure is discussed: as single hydrocytes or residual formation of mesarch bundles. The systematic position of this wood remains problematic.