Palaeoginkgoxylon zhoui, a new ginkgophyte wood from the Guadalupian (Permian) of China and its evolutionary implications

A new taxon of ginkgophyte affinity Palaeoginkgoxylon zhoui gen. nov. et sp. nov. is described from the Guadalupian Lower Shihhotse Formation of the Hulstai coalfield, Inner Mongolia Autonomous Region (Nei Mongol), northern China, on the basis of the anatomical structures of the broad eustele and pycnoxylic secondary xylem. The anatomical structure of the new woody tree trunk resembles both the early gymnosperms of Eristophyton-Pitus types and the modern Ginkgo. Therefore, the new tree trunk is interpreted as representing a transitional stage in the evolution of Ginkgo from early arborescent lignophytes since the Early Carboniferous.     

Sclerospiroxylon xinjiangensis nov. sp., a gymnospermous wood from the Kungurian (lower Permian) southern Bogda Mountains,northwestern China: Systematics and palaeoecology

A new silicified wood, Sclerospiroxylon xinjiangensis Wan, Yang et Wang nov. sp., is described from the Cisuralian (lower Permian) Hongyanchi Formation in southeast Tarlong section, Turpan City, Xinjiang Uygur Autonomous Region, northwestern China. The fossil wood is composed of pith, primary xylem and Prototaxoxylon-type secondary xylem. The pith is solid, circular, heterocellular, with sclerenchyma and parenchyma. The primary xylem is endarch to mesarch, with scalariform thickenings on tracheid walls. The secondary xylem is pycnoxylic, composed of tracheids and parenchymatous rays. Growth rings are distinct. Tracheids have mostly uniseriate, partially biseriate araucarian pitting on their radial walls. Helical thickenings are always present on both the radial and the tangential walls. Rays are 2–14 cells high, with smooth walls. There are 2 to 7, commonly 2 to 4 cupressoid pits in each cross-field. Leaf traces suggest that S. xinjiangensis nov. sp. was evergreen with a leaf retention time of at least 15 years. Based on the sedimentological evidence, growth rings within the S. xinjiangensis nov. sp. could have been caused by seasonal climatic variations, with unfavorable seasons of drought or low temperature. Low percentage of latewood in each growth ring is probably due to the intensity of climatic seasonality and/or long leaf longevity.     

ANATOMICALLY PRESERVED GLOSSOPTERIS STEMS WITH ATTACHED LEAVES FROM THE CENTRAL TRANSANTARCTIC MOUNTAINS,ANTARCTICA

Stems and buds of Glossopteris skaarensis Pigg and buds of G. schopfii Pigg from the Permian Skaar Ridge locality in the central Transantarctic Mountains, Antarctica demonstrate the first anatomically preserved glossopterids known with stem/leaf attachment. Stems of G. skaarensis are 1–12 mm in diameter ( = 3.1 mm) with a broad pith, poorly defined primary xylem, and a zone of secondary xylem up to 6 mm thick. Pycnoxylic wood conforming to Araucarioxylon Kraus is composed of tracheids with uni- to biseriate oval to hexagonal bordered pits on radial walls, uniseriate rays one to a few cells high, and cupressoid to taxodioid cross-field pitting. Stems have a narrow zone of secondary phloem, aerenchymatous cortex with scattered sclereids, and sometimes a narrow periderm. Two wedge-shaped leaf traces each bifurcate to form four strands in the base of each petiole. Small axillary branches are vascularized by double branch traces that fuse at the margin of the main axis. Buds of G. skaarensis have leaves with narrow lateral laminae and a thickened midrib containing a wide lacuna, delicate vascular strands, and a prominent hypodermis. In contrast, buds of G. schopfii have uniformly thick leaves with prominent, circular vascular bundle sheaths. These anatomical details are used to reconstruct individual types of glossopterid plants, providing new information toward understanding the ecology and evolution of this important group of Permian seed plants.     

A microstructure study on silicified wood from the Permian Petrified Forest of Chemnitz

Three typical plant taxa from the fossil assemblage of the 290-million-year-old Chemnitz Petrified Forest (Zeisigwald Tuff Horizon, Leukersdorf Formation) were studied with regard to the microstructure of the petrifactions: samples of the tree fern Psaronius sp., the seed fern Medullosa stellata, and the gymnosperm Dadoxylon sp. The plant’s tissues are anatomically preserved by silica exhibiting different crystalline order and by other mineralisations. Specimens were studied by means of electron backscatter imaging and electron backscatter diffraction in a scanning electron microscope. The cell walls were largely preserved by quartz crystals, the cell lumina by cryptocrystalline silica. The former organisation and chemical composition of the vascular tissue are mirrored by varying grain formation and grain size. Results are discussed in terms of extant xylem cell wall organisation showing highly hydrophilic cellulose and hemicellulose cross-linked by hydrophobic lignin. The effect of polar and non-polar wood components on the precipitation of silica from aqueous solution and on the formation of crystals is convincing, and the reported results provide a better understanding of how silica replaced organic matter during the petrifaction process.     

New petrified gymnosperms from the Permian of Maranhão (Pedra de Fogo Formation), Brazil: Ductolobatopitys nov. gen. and Kaokoxylon

Continuing the study of petrified gymnosperm trunks recovered from the Pedra de Fogo Formation, we identify here two new taxa from the Permian deposits of the Parnaíba Basin, northeastern Brazil. One taxon is an endemic form named Ductolobatopitys mussae Conceição, Neregato et Iannuzzi, nov. gen., nov. sp., characterized by solenoid, lobed and non-septate heterocellular pith, cauline bundles with endarch maturation, and secondary xylem with araucarian radial pitting on the tracheid walls. The other form is assigned to the genus Kaokoxylon, which has been recorded from most of Gondwana, including the Parnaíba Basin, but is recorded for the first time from the Pedra de Fogo Formation with the new species Kaokoxylon brasiliensis. It is characterized by solid, non-septate heterocellular pith with sclerenchyma cells, endarch cauline bundles, and uni-to triseriate radial pitting on the walls of the tracheids. The sedimentological interpretations of the outcrops where the fossils were collected indicate that these plants lived on the shores of large continental lakes, with relatively high humidity but possibly periods of drought. These inferences are supported by growth interruptions in the secondary xylem, the presence of calamitalean and tree-fern stems, and microbialites that crop in the same area. These new finds not only increase the known diversity of the flora in the Pedra de Fogo Formation, but also provide more accurate information for understanding the floristic elements that formed the subtropical flora during the Cisuralian in this basin in Western Gondwana.     

Bivalves from Carboniferous glacial deposits of western Argentina

Late Palaeozoic glaciation of Gondwana affected ecosystems and caused provincialism in the earth’s biota. Periglacial seas favored the origin of endemic genera and species, and remarkable differences exist with faunas of the Palaeoequatorial realm. Carboniferous glacimarine deposits are almost everywhere associated with theLevipustula levis “cold” fauna. These bio- and lithofacies are ubiquitous along the peri-Gondwana belt that stretches from western Argentina to eastern Australia, including central Patagonia and Antarctica. Both glacial sediments and theLevipustula levis Zone are assumed to date from the beginning of the Namurian to an indeterminated part of the early Westphalian. The bivalve fauna associated with the Carboniferous glacial deposits of western Argentina is described, including four new species:Promytilus grandis n. sp.,Leptodesma (Leiopteria) aredesi n. sp.,Oriocrassatella andina n. sp., andMyofossa calingastensis n. sp. Six insufficiently preserved species are left in open nomenclature:Leptodesma (Leiopteria) n. sp.,Euchondria n. sp.,Schizodus n. sp.,Promytilus sp.,Cypricardinia? sp., andStreblopteria? sp.; it proved even impossible to decide whether a badly damaged incomplete specimen belongs toMyonia orVacunella. Five other species, which are known from single specimens, are assigned tentatively to the generaPhestia, Atomodesma, Pyramus, Vacunella, andPleurophorella.     

Arachnids from the Carboniferous of Russia and Ukraine,and the Permian of Kazakhstan

New finds of Late Palaeozoic arachnids, based on three well-preserved carapaces from the Carboniferous of Russia and Ukraine and one complete, albeit poorly preserved, specimen from the Permian of Kazakhstan, are described. The spider genus Arthrolycosa is reported from the Late Carboniferous (Late Pennsylvanian: Kasimovian–Gzhelian) of Chunya in the Tunguska Basin of Siberia; it is the first find of a spider outside the Carboniferous tropics. Another fossil assigned to the same genus comes from the Late Carboniferous (Early Pennsylvanian: Bashkirian) of Kamensk–Shakhtinsky in the Donets Basin of Russia; it is probably the oldest fossil spider known. A thelyphonid (whip scorpion) carapace is described from the Late Carboniferous (Late Pennsylvanian: Kasimovian) of the adjacent Lugansk Province of the Donets Basin of Ukraine.     

A WOODY LYCOPSID STEM FROM THE NEW ALBANY SHALE (LOWER MISSISSIPPIAN) OF KENTUCKY

A lycopsid axis from the New Albany Shale (Sanderson Formation) of Kentucky is described. The stem, which branches dichotomously, is 45 mm in diameter and is characterized by a relatively narrow parenchymatized protostele, a 3.0 mm-thick cylinder of secondary xylem, a tripartite cortex, and a periderm that is more than 5.0 mm thick. The secondary xylem is composed of uniseriate and biseriate vascular rays and narrow tracheids with scalariform wall thickenings on both radial and tangential walls. The periderm is characterized by elongate, thick-walled cells, some of which broaden tangentially in the outer part of the tissue forming zones that appear wedge-shaped in cross section. Surface features of the axis, including leaf bases, are not preserved. The stem is tentatively regarded as a member of the Lepidodendrales in accordance with the numerous anatomical characters that it shares with more recent representatives of the order. Because the external morphology is not known, however, the possibility exists that the axis corresponds to a protolepidodendralean taxon currently known only from compression and/or impression remains or some other nonlepidodendralean plant that produced secondary xylem. The extremely narrow profile of the secondary xylem tracheids (relative to other arborescent lycopsids) is interpreted as evidence that the plants grew in a habitat that was substantially drier than the Upper Carboniferous coal swamps.     

Charred wood of Prototaxoxylon from the Wuchiapingian Wutonggou Formation (Permian) of Dalongkou,northern Bogda Mountains,northwestern China

Charred wood occurs sporadically in sedimentary rocks in China. A marcroscopic charcoal with well-preserved anatomical structure is described from the Wuchiapiangian Wutonggou Formation in the southern part of Dalongkou section, northern Bogda Mountains in the Junggar Basin, northwestern China. It is characterized by uniseriate radial tracheidal pitting, taxaceous tertiary spiral thickenings in the tracheidal walls, uniseriate tangential tracheidal pitting, homogeneous, uniseriate, 2–10 cells high xylem rays, and 1–2 pits in each cross-field. It is assigned to Prototaxoxylon uniseriale Prasad. The uniseriate, bordered, contiguous, rarely separate tangential pitting of P. uniseriale is evidenced clearly for the first time. The features of this species show a close affinity with conifers. The coniferous charred wood may have been derived from an extrabasinal forest, perhaps from upland environment deep within the hinterland, according to results of modern taphonomic research.     

Devonian and Carboniferous dendroid graptolites from Belgium and their significance for the taxonomy of the Dendroidea

Devonian and Carboniferous dendroid graptolites from Belgium are evaluated and partly revised. New finds in two different stratigraphic intervals of the ‘Carrière de Lompret’, an active quarry exploiting Frasnian limestones and shales east of Frasnes-lez-Couvin, allow the identification of Callograptus sp. and Dictyonema fraiponti, both belonging to the dendroid family Acanthograptidae. The relatively high diversity of the dendroid graptolite fauna from the Viséan Marbre noir de Denée, one of the few Carboniferous graptolite faunas in the world, can be shown to be based on astogenetic and preservational aspects. Nearly all known specimens can be included in the highly variable Dictyonema fraiponti, a fan-shaped large dendroid species with complex stipes formed from tubular thecae, possessing simple to complex bridges connecting adjacent stipes. Some of the graptolite material is well preserved and provides important information on the tubarium construction of Devonian to Carboniferous dendroid graptolites and, thus, is highly significant for a taxonomic and phylogenetic understanding of the youngest dendroid graptolite faunas worldwide. The genera Callograptus and Ptiograptus are revised based on their type species (Callograptus elegans from Quebec, Canada; Ptiograptus percorrugatus from the Silurian or Devonian of Kentucky, USA) and referred to the Acanthograptidae.     

INCREASE IN CELL WALL SURFACE AREA DURING ENLARGEMENT OF CAMBIAL DERIVATIVES IN ABIES CONCOLOR

Wilson , Brayton F. (U. California, Berkeley). Increase in cell wall surface area during enlargement of cambial derivatives in Abies eoncolor . Amer. Jour. Bot. 50(1): 95–102. Illus. 1963.— Dimensions of fusiform cells (tracheids and sieve cells) and ray cells were measured from samples of the 1960 xylem and phloem increment of 5 trees felled at monthly intervals from April through July, 1960. Calculations using these measurements gave the magnitude, direction and rate of increase in cell wall surface area during enlargement. Although 14 times more tracheids than sieve cells were produced, both cell types enlarged mostly in a radial direction (up to 400%) at the same rate (20–33 × 10³μ² wall surface area/day) to the same final size. Fusiform cambial cells doubled their wall area between successive periclinal divisions. Calculations showed that ⅞ of this increase was in the radial walls of the daughter cells at a rate comparable to that in enlarging tracheids and sieve cells; the other ⅞ was from cell plate formation at an estimated rate of 187–327 × 10³μ²/day. Enlargement of derivatives in the radial direction largely determined the amount of increase in wall area. Besides radial enlargement, tracheids also elongated (up to 13%) and phloem cells enlarged tangentially (sieve cells up to 36%; pholem ray cells up to 60%). The relationships of enlarging tracheids and xylem ray cells are discussed, and it is suggested that slippage may occur between the developing walls.     

New data on the distribution of the Upper Carboniferous (Pennsylvanian) flexible crinoid Cibolocrinus (Crinoidea,Flexibilia)

Two new species of flexible crinoids of the genus Cibolocrinus (Crinoidea, Flexibilia) from the Upper Carboniferous of the Moscow Region are described: C. kutasovi (Moscovian Stage, Podolskian Regional Substage) and C. gerassimovi (Gzhelian Stage, Dobryatinian Regional Substage). The first species, C. kutasovi, belongs to a group with low cone shaped cups that first appeared in the Moscow Basin and then spread to the Midcontinent of North America. In one specimen of C. gerassimovi the smallest infrabasal plate is situated in the A ray, which is not typical for flexible crinoids. A poorly preserved crown of Cibolocrinus sp. from the Upper Carboniferous (Gzhelian Stage) of the Darvaz Ridge (western Pamir, central Tajikistan) is also described. The described specimens of Cibolocrinus from the Moscow Region and the Darvaz Ridge are the first reliable specimens of this genus described from Europe and Asia.     

Anatomically preserved lepidodendralean plants from lower permian coal balls of northern China: Achlamydocarpon intermedium sp. nov.

Lepidodendralean lycopsids, a dominant component in Late Palaeozoic wetland plant communities, possess a diversity of reproductive structures that are primarily known from the Late Palaeozoic floras of Europe and North America. Here we document an anatomically preserved lepidodendralean lycopsid sporophyll with attached megasporangium from the Lower Permian Taiyuan Formation in Shanxi Province, northern China. The sporophyll has a pedicel onto which the sporangium is attached, and the sporangium is dorsiventrally flattened, proximally dehiscent and longitudinal ridged. The megasporangial wall comprises three zones: an outer uniseriate layer of columnar cells, a middle layer 1–3 cells thick comprising isodiametric parenchymatous cells, and an inner zone 1–3 cells thick of thick-walled cells. The vascular system comprises a single xylem strand surrounded by zone of parenchyma that continues through the pedicel into the lamina. Within the megasporangium a single functional megaspore and three abortive megaspores occur. Features of this specimen conform to Achlamydocarpon Schumacher-Lambry, and comparisons with other species show it shares similarities with A. takhtajanii (Sni.) Schumacher-Lambry and A. varius Taylor and Brack-Hanes. Although the morphology and anatomy of the specimen we describe overlaps with these two species, it is distinct from both leading to the erection of the new species A. intermedium sp. nov. The evolutionary significance of A. intermedium sp. nov. and the identity of its parent plant are considered, and the status and systematic position of “Oriental lepidophytes” from the Cathaysian floras are discussed.     

类短命植物阿尔泰独尾草的解剖学研究

通过常规石蜡切片法,对类短命植物阿尔泰独尾草的根、茎、叶、花等器官进行了解剖结构的研究。结果表明：阿尔泰独尾草的根系有明显的二型性,即有储藏根和吸收根的结构与功能分化,是其对生长发育快速、年休眠期长的类短命植物生活习性高度适应的结果;其营养器官表现出明显的旱生植物特征;储藏根与吸收根木质部的二型性及其内皮层的带状凯氏带增厚结构则说明独尾草属植物可能具有较为特殊的系统演化地位。     

THE PHLOEM OF ETAPTERIS LECLERCQII AND BOTRYOPTERIS TRIDENTATA

The phloem of Etapteris leclercqii and Botryopteris tridentata petioles is described from Lower Pennsylvanian coal balls. Petioles of B. tridentata are characterized in transverse section by an omega-shaped xylem trace, a phloem zone which extends from 2-10 cells in width, and 2-parted cortex. Etapteris leclercqii petioles exhibit a 4–9 cell-wide phloem zone surrounding the central clepsydroid xylem mass, and a 3-parted cortex. In both taxa a 1–2 cell layer parenchyma sheath separates the xylem from the extra-xylary tissues. The phloem of both species consists of sieve elements that average about 20 μm in diam by 200 μm in length in Botryopteris, and 100 μm in length in Etapteris, with horizontal-slightly oblique end walls. In transmitted light, the radial walls of the sieve elements form an irregular reticulate pattern enclosing elliptical lighter areas. With the scanning electron microscope, these areas appear as horizontal-slightly oblique furrows on the cell wall, with many small indentations lining the furrows. These indentations, because of their regular occurrence and size (from a few fractions of a micron up to 1.0 μm in diam), are interpreted as sieve pores, and the elliptical areas that enclose them as sieve areas. The phloem of E. leclercqii and B. tridentata is compared with that described for other fossil genera and with that of extant ferns.     

Anatomical features that facilitate radial flow across growth rings and from xylem to cambium in Cryptomeria japonica

Background and Aims

Although the lateral movement of water and gas in tree stems is an important issue for understanding tree physiology, as well as for the development of wood preservation technologies, little is known about the vascular pathways for radial flow. The aim of the current study was to understand the occurrence and the structure of anatomical features of sugi (Cryptomeria japonica) wood including the tracheid networks, and area fractions of intertracheary pits, tangential walls of ray cells and radial intercellular spaces that may be related to the radial permeability (conductivity) of the xylem.

Methods

Wood structure was investigated by light microscopy and scanning electron microscopy of traditional wood anatomical preparations and by a new method of exposed tangential faces of growth-ring boundaries.

Key Results

Radial wall pitting and radial grain in earlywood and tangential wall pitting in latewood provide a direct connection between subsequent tangential layers of tracheids. Bordered pit pairs occur frequently between earlywood and latewood tracheids on both sides of a growth-ring boundary. In the tangential face of the xylem at the interface with the cambium, the area fraction of intertracheary pit membranes is similar to that of rays (2·8 % and 2·9 %, respectively). The intercellular spaces of rays are continuous across growth-ring boundaries. In the samples, the mean cross-sectional area of individual radial intercellular spaces was 1·2 µm² and their total volume was 0·06 % of that of the xylem and 2·07 % of the volume of rays.

Conclusions

A tracheid network can provide lateral apoplastic transport of substances in the secondary xylem of sugi. The intertracheid pits in growth-ring boundaries can be considered an important pathway, distinct from that of the rays, for transport of water across growth rings and from xylem to cambium.Key words: Cryptomeria japonica, bordered pit, intercellular spaces, lateral transport, tracheid network, water conduction, xylem permeability     

Comparison of the effects of canopy and understory nitrogen addition on xylem growth of two dominant species in a warm temperate forest,China

Understanding the effect of increasing atmospheric nitrogen (N) deposition on xylem growth of trees is critical to predict tree growth and carbon sequestration under global change. Canopy N addition (CAN) is generally believed to realistically simulate atmospheric N deposition on terrestrial ecosystems given it takes all processes of N deposition from forest canopy to belowground into account. However, whether CAN is more effective in reflecting the effect of atmospheric N deposition on xylem growth of trees than understory N addition (UAN) has been rarely reported. To address the question, we conducted a CAN vs. UAN experimental study to weekly monitor xylem growth of two dominant broadleaf species (Quercus acutissima Carruth. and Quercus variabilis Blume) in a warm temperate forest of China during 2014–2015. Weekly xylem increment during the two years was measured. Mixed-effects models were used to quantify the effects of N addition on xylem growth and detect the differences among treatments. We found that CAN of 50 kg N ha⁻¹ yr⁻¹ plays a more significant role in promoting xylem growth of Q. acutissima than UAN of 50 kg N ha⁻¹ yr⁻¹, and significantly enhanced the formation of differentiating xylem (zones of radial enlarging and wall-thickening cells) of Q. acutissima in the early growing season (April-June) and the rate of xylem increment, but no significant difference in xylem increment of Q. variabilis was detected between CAN50 and UAN50. This is the first study to quantitatively demonstrate that previous UAN studies may have underestimated the effects of atmospheric N deposition on tree growth by ignoring the N interception through forest canopy. Furthermore, our study also suggested a species-specific response of xylem growth to N addition. Under a certain amount of atmospheric N deposition in the future, the xylem increment of Q. acutissima may be superior to that of Q. variabilis.     

Re-interpretation of Wexfordia hookense from the Upper Devonian of Ireland as an arborescent lycophyte

New collections of pyritized axes of the lycophyte Wexfordia hookense have been made from the Upper Devonian (uppermost Famennian) type locality at Sandeel Bay, County Wexford, in south-eastern Ireland. The specimens reveal additional histological features that permit reinterpretation of the morphology of this taxon and reevaluation of its taxonomic affinities. Wexfordia is shown to possess both secondary xylem, with narrow, uni- to biseriate rays, and periderm. The range of variation in relative amounts of primary and secondary xylem can be correlated with position in the mature plant. This evidence indicates that Wexfordia was a small tree rather than an herbaceous form. Fine structure of tracheids and additional anatomical features strongly support affinities with Carboniferous arborescent Isoetales, rather than Devonian Protolepidodendrales, and further support the hypothesis that radiation in this lineage was well underway prior to the Carboniferous.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 275–287.     

Ginkgoalean woods from the Jurassic of Argentina: Taxonomic considerations and palaeogeographical distribution

A specimen of Baieroxylon rocablanquense nov. sp. from the Roca Blanca Formation (Early Jurassic), and a specimen of Ginkgomyeloxylon tanzanii Giraud and Hankel from the La Matilde Formation (Middle Jurassic), both located in the Santa Cruz province, Argentina, are described in detail. Identification of the morphogenus Baieroxylon is based upon secondary xylem characteristics (cross-field tracheid pitting, cross-fields and ray characters), while identification of Ginkgomyeloxylon is based upon pith, primary xylem and secondary xylem features. A synthesis of Ginkgoalean woods is presented, which combines diagnostic anatomical evidence with data related to stratigraphic and paleogeographical distributions. Based on the results of this analysis, a key for genus-level identification is provided and a new genus, Ginkgopitys, is proposed. These results are used to elucidate global patterns of historical distribution over the course of geological time. In Gondwana, a great diversity of “mixed-type” woods was present during the Mesozoic, especially during the Late Triassic. In contrast, in Laurasia a lower diversity of the mixed-type is recorded for the Paleozoic and Mesozoic, with increases in “abietinoid-type” wood – similar to extant Ginkgo – taking place at the beginning of the Cretaceous. During the Jurassic and Early Cretaceous in both Laurasia and Gondwana, mixed-type and abietinoid-type woods co-existed, illustrating that important evolutionary changes in wood anatomy occurred during the Mesozoic (Jurassic-Cretaceous).