Multiseriate Rays Research Articles

STUDY ON ANATOMICAL CHARACTERIZATIONOF RHINACANTHUS NASUTUS (L.) KURZ

Rhinacanthus nasutus (L.) Kurz, belonging to the family Acanthaceae, is an herbaceous shrub. This plant holds significant value in traditional medicine. The leaves of R. nasutus are commercially available as tea bags, marketed as a natural remedy for various ailments. However, the conservation status of R. nasutus necessitates appropriate protective measures to ensure its sustainability. Anatomical studies provide various histological layers, including the epidermis, cortex, vascular bundles, and pith. The leaves feature numerous diacytic stomata and hypostomatic nature. The leaf midrib exhibits a narrow epidermis with numerous glandular hairs. The medulla contains arc-shaped vascular bundles and lateral accessory bundles, with the stele comprising linear xylem elements towards the inner side and phloem elements on the outer region. Transfusion tracheids are present between the palisade and spongy cells, with tissues containing large quantities of oil droplets. The petiole shows a narrow epidermis with numerous glandular hairs. The vascular region features a V-shaped stele. The stem reveals the stelar region is extensive and the inner region is rich in developed xylem elements with linear multiple vessels. The medullary ray cells are narrow, and the pith region displays intruded primary xylem with thick-walled parenchyma cells. Wood anatomical analysis shows xylem parenchyma cells that are paratracheal. The vessel elements possessing perforation plates and transverse walls with bordered pits. Tracheids have a narrow lumen, and the lateral walls contain simple pits. The wood demonstrates multiseriate ray parenchyma and the bark consists of phloem rays and narrow fibers. In conclusion, R. nasutus exhibits a variety of histological and anatomical characteristics that support its traditional medicinal uses. The detailed anatomical studies contribute to understanding the plants structural adaptations and potential environmental interactions, thereby facilitating its identification and utilization in herbal medicine. The conservation of this species is critical to preserving its medicinal value and ensuring its availability for future research and therapeutic applications.

STUDY ON ANATOMICAL CHARACTERIZATIONOF EXOTIC SPECIES AMHERSTIA NOBILIS WALL

Amherstia nobilis, known as the Pride of Burma and colloquially referred to as Simshipa-vriksham, is a remarkable and rare tropical tree celebrated in Indian mythology, especially within the context of the epic Ramayana. Often dubbed the Queen of Flowering Trees. The species was named in honour of Lady Sarah Amherst, an early collector of Asian plants, and it stands as the sole representative of its genus. This study involves microscopic examination of various parts of the plant, revealing intricate details about its cellular structure, vascular arrangements, and overall morphology. Mature leaves of A. nobilis, for instance, have been analyzed micro-morphologically, with an average leaf area calculated. The leaves are characterized by numerous rubiaceous stomata, as hypostomatic. In the leaf midrib, the vascular area appears oval and vascular elements are U-shaped. The leaf lamina flanked by highly cutinized upper and lower epidermis layers. The palisade tissue is bi-layered, while the lower leaf lamina features loosely packed spongy layers with numerous vein bundles and large air spaces and contains starch grains. Histological examination of the rachis reveals an oval shape with a slightly thick-walled epidermis and hypodermis containing air cavities. The vascular region is well-differentiated withxylem elements in linear multiples. The secondary phloem elementspossess numerous prismatic crystals and patches of phloem fibers. In the mature stem, periderm formation, with a highly reduced cortical region containing chlorenchymatous cells. The vascular region comprises phloem tissues with patches of phloem fibers. The xylem is with large vessels arranged in linear multiples. The pith is highly reduced with included phloem elements. Wood anatomy reveals the vessels displaying paratracheal parenchyma distribution, appearing as aliform or eyelet type. The vessel elements are arranged in linear multiples, and the radial longitudinal section shows large vessel elements with bordered pits separated by end plates. The bark showed uni- and multi-seriate ray cells, long and narrow phloem parenchyma, and prismatic crystal deposits in phloem ray-parenchyma cells. The parenchyma cells are traversed by numerous phloem fibers, with starch granules deposited in phloem parenchyma. In conclusion, Amherstia nobilis, the Pride of Burma, exemplifies a unique combination of aesthetic appeal and complex anatomical structure, making it a subject of significant interest in botanical and horticultural research. Detailed histological and anatomical studies provide crucial insights into the species unique adaptations and structural features, underscoring the need for continued conservation efforts to protect this majestic and rare tropical tree.

COMPARATIVE WOOD ANATOMY OF FOUR Vernonia delile SPECIES (ASTERACEAE) IN SOUTHWESTERN NIGERIA.

Wood anatomy of four Vernonia Delile species in Southwestern States of Nigeria was investigated with a view to identifying the anatomical features of the genus that could be used to delimit the taxa. Plant samples were collected from Oyo, Ekiti, Osun and Ondo States. Transverse, tangential and radial longitudinal sections were made from the wood of the species of Vernonia using Reichert sliding microtome at 10μm thickness. The woods were also macerated with Schultze's uid to separate the tissues and cells. The macerates and cut sections were stained with Safranine O reagent to reveal the differences in tissue arrangements, shapes and cell inclusions. The four species showed common anatomical features: pore shape at transverse plane are oval, round, rectangular circular to cylindrical, simple pitting of vessel elements and presence of - uniseriate, biseriate and multiseriate rays. The wood characteristics that can be used to distinguish the taxa are absent and presence of : tylose, bre length and percentage of solitary vessel, axial parenchyma type and its absence. These features conferred signicant taxonomic difference in the species and members were categorized into three major groups. These ndings serve as baseline for further research such as molecular studies.

Qualitative and quantitative anatomical characteristics and radial variation of major cell components in Paulownia tomentosa wood grown in Korea

Qualitative and quantitative anatomical characteristics and radial variations of the major cell components in Paulownia tomentosa wood were examined using optical microscopy and X-ray diffraction to aid in wood identification and as quality indices. The vessel arrangement on the transverse surface was either ring-porous or semi-ring-porous. Most vessels had solitary pores, while some vessels had multiple radial pores. The axial parenchyma was generally confluent and partially of aliform type. Tyloses with high frequency in the vessel lumen and multiseriate rays (2 to 5 cells) were typical. The vessel diameter of earlywood and latewood was approximately 240 and 107 μm, respectively, with a range of 165 to 289 μm in earlywood and 55 to 149 μm in latewood. Ray height and fiber length were approximately 178 and 740 μm, respectively. The vessel diameter in both earlywood and latewood and the fiber length increased gradually with an increasing number of growth rings. Ray height was constant from the pith to the middle section and decreased toward the bark. The anatomical characteristics and radial variation of major components of P. tomentosa can be used as wood identification keys and quality indices.

Anatomical Study of Shorea robusta Gaertn.

Shorea robusta, commonly known as Sal, is one of the multipurpose timber trees in Nepal. This study aims to carry out detailed anatomical investigation of the wood and leaf anatomical traits of Sal. The wood and leaf samples of Sal were collected from Rupandehi district, Nepal. Wood of Sal was found to be diffuse-porous and the vessels were mostly solitary or paired and sometimes in a short radial multiple. Non-septate, vasicentric fibres forming solid tracts connected the vessels and rays; vasicentric parenchyma with lozenge aliform to aliform confluent arrangement; moderately broad, multiseriate rays and the presence of prismatic crystals in rays were the characteristic feature of the wood. Leaves were hypostomatic and the stomata were cyclocytic with four or more subsidiary cells surrounding the guard cells. Stellate, glandular trichomes were present in upper epidermis, while unicellular, simple, glandular, tufted trichomes were present in the lower epidermis. The increase in global trade has resulted in over-exploitation of forest resources, and hence in the present context, the identification and traceability of wood is highly crucial. The outcomes of this study are supposed to help in the identification of wood of Sal through their anatomical study.

Mechanical properties of charcoal and its representativeness of vegetation in northern China.

The objective of this paper is to examine the representativeness of charcoal taxa at archeological sites in northern China. We carried out standardized laboratory compression tests on 168 samples representing 21 taxa charred at four different temperatures to characterize the mechanical properties of common taxa in temperate China. The results indicate that significant fragmentation differences occur between taxa. Ring-porous/semi-ring-porous taxa with a moderate density (>0.55 g/cm3) are overrepresented, while those with a very low to low density (<0.55 g/cm3) are moderately represented. Diffuse-porous taxa with slightly dense uniseriate rays, rare multiseriate rays and distinct helical thickenings are underrepresented, and those with slightly dense multiseriate rays are overrepresented, while those with rare to moderate multiseriate rays and helical thickening absence are moderately represented. Gymnosperm trees are generally well represented. Among the ubiquitous taxa at the archeological sites across northern China, Quercus and Ulmus may be overrepresented, and Pinus, Salix, Populus, and Acer may be underrepresented, while Betula may be moderately represented.

Influence of Colder Temperature on the Axial and Radial Parenchyma Fraction of Quercus ciliaris C.C.Huang &amp; Y.T.Chang Wood and Its Relationship with Carbohydrate Reserve (NSC)

Parenchyma in the secondary xylem comprises the main tissue for the storage of non-structural carbohydrates (NSC) in woody plants. Across species, the amount of parenchyma depends on the general environment of the distribution area and determines to a large extent the NSC storage. However, little information is available on the relationship between parenchyma fractions, NSC storage, and the environmental influences within individual species. This information is crucial to assessing the adaptive capacities of tree populations in the context of increasing the frequency and severity of stress-inducing events. In this study, parenchyma fractions and NSC concentrations of the secondary xylem in trunks of a subtropical evergreen oak (Quercus ciliaris C.C.Huang &amp; Y.T.Chang) were quantified along an elevational gradient from 700 m to 1200 m a.s.l. in eastern China. Air temperatures within the distribution area correlated with altitude were recorded. The results showed that the total parenchyma fractions did not covary with the colder temperatures. However, axial parenchyma fractions were lower with a colder climate, while the fractions of multiseriate rays and total ray parenchyma were higher. Higher concentrations of starch and NSC were significantly associated with larger axial parenchyma fractions. The sugar concentration displayed no significant relationship with parenchyma fractions. These findings suggest that the total parenchyma fractions in secondary xylem do not increase in response to a colder climate, while colder temperatures drive changes in the composition of parenchyma for Q. ciliaris.

Wood anatomical features of some Nigerian species of Acacia Mill and their suitability for paper making

A comparative wood anatomical study of six species of the genus Acacia commonly found in Nigeria was carried out. Wood samples were collected from matured branches of plants in different locations in Mazah and Shere Hills, Jos, Plateau State, Nigeria. Transverse, tangential and radial longitudinal sections as well as wood macerates were prepared and mounted unto microscopic slides using standard anatomical methods. All the species had diffused porous wood, heterogeneous rays, aseptate fibres and predominantly solitary vessels with simple perforation plate, few pore clusters and pore multiples. Banded paratracheal axial parenchyma was common in all taxa except in A. senegal which was predominantly paratracheal without bands. Multiseriate rays were common features in all taxa except in A. nilotica which had predominantly uniseriate rays. Quantitative wood anatomical characters such as fibre length, fibre diameter, fibre lumen diameter, fibre wall thickness, vessel length, vessel diameter, ray length, ray diameter and pore diameter were of taxonomic importance in the delimitation of the studied taxa. The Runkel ratio of A. senegal (0.99µm) compared favourably with some hardwood species in the Nigerian rainforest ecosystem hence this taxon could be exploited for pulp and paper in Nigeria.

New dicotyledonous woods from the San Carlos Formation (Upper Cretaceous) in Northern Mexico

Summary We describe two new fossil woods from the San Carlos Formation (Upper Cretaceous), Chihuahua State, Mexico. The first wood resembles the fossil genus Metcalfeoxylon in having solitary vessels, scalariform perforation plates, vessel-ray parenchyma pits of similar size as the intervessel pits, axial parenchyma apotracheal diffuse and diffuse in aggregates, and heterocellular multiseriate rays with long, uniseriate tails. The second wood is a new fossil genus, and it is characterized by having diffuse porous wood, vessels predominantly solitary, vessel outlines oval and tending to be of two diameter classes, simple perforation plates, minute alternate intervessel pits, vessel-ray parenchyma pits similar to intervessel pits in size and shape, vasicentric tracheids, non-septate fibers, homocellular rays, and exclusively uniseriate and biseriate rays. This combination of features supports its placement in Myrtales (?Myrtaceae), in a new fossil-genus named Lazarocardenasoxylon. These two new records provide more information about the floristic composition of the Late Cretaceous flora of the San Carlos Formation and its relationship with those from the southern USA. However, a definitive picture of the floristic relationship of these Cretaceous floras of northern Mexico and southern USA remains elusive.

Wood Anatomy of Argophyllaceae (Asterales): Adaptation in a Small Clade

Argophyllaceae (Argophyllum, 14 spp.; Corokia, 6 spp.; Lautea, 1 sp.), are shrubs that occur in the southwestern Pacific and eastern Australia. They occur in habitats where moisture is relatively common but dry days and mild frost may occur. The woods of these genera show enough distinctive features to justify their grouping in a single family: perforation plates with 10–20 bars, vessel elements narrow and numerous per mm2, imperforate tracheary elements about 50% longer than the vessel elements, axial parenchyma scarce, diffuse, multiseriate rays narrow and heterocellular (upright cells common in uniseriate rays), crystals absent, gum deposits common. These features group the genera of Argophyllaceae more closely with each other than with the nearest families in Asterales (Alseuosmiaceae, Phellinaceae). Probable apomorphies of the genera include helical thickenings in vessels and tracheids, together with abundant tracheids and rare septate fiber-tracheids (Corokia); almost total absence of axial parenchyma and tracheids combined with maximal abundance of septate fiber-tracheids and no helical thickenings (Argophyllum, Lautea). Lautea, formerly included within Corokia, has floral and foliar distinctions and is endemic to a single island, Rapa Iti. Woods of Argophyllaceae are alike in their ecological adaptations (perforation plates, vessel diameter and density) but the presence of tracheids and helical thickenings in Corokia suggest adaptations to frost and mild drought. As expected, vessels group more prominently in the tracheid-free species (Argophyllum, Lautea) but very little in the tracheid-rich genus Corokia.

First fossil record in Tambería formation (Neogene) in Bolsón de Fiambalá, Catamarca province, Argentina: Palaeoenvironmental inferences through Leguminosae woods

The aim of this study is to report the first fossil wood record of Leguminosae in miocene sediments from Tambería Formation outcropping in the center-west of Catamarca province, Argentina. This Leguminosae specimen was found on levels of multi-colored sandstones that alternated with dark brown pelites and gray conglomerates. It is characterized by the presence of: semi-ring porous wood with vestured ornamented pits, helicoidal thickenings on the vessel walls, paratracheal parenchyma, homogeneous and multiseriate rays, all of which justify its assignment to Gleditsioxylon Müller-Stoll and Mädel. Six species are known and distributed in: Argentina, the United States, China and Japan in Miocene sediments coetaneous with sediments from Tambería Formation. The fossil wood specimen documented in this study is assigned to Gleditsioxylon fiambalense nov. sp. taking into account the combination of its anatomical features. Vulnerability and mesomorphy indices reveal its subtropical environmental condition which is not only typical of Gleditsia amorphoides, the current species, but also coincides with the palaeoenvironmental inferences derived from sedimentological research. This first paleontological record promises interesting analyses to understand the paleobiological and paleoecological aspects of the Tambería Formation and adds another new evidence to show the diversity of the neogene Leguminosae lignofloras of northern Argentina.

Morphological and wood anatomical traits of Rhododendron lepidotum Wall ex G. Don along the elevation gradients in Nepal Himalayas

ABSTRACT Though variability in morphological features along the environmental gradients has been extensively studied, less information is available on possible adaptations and trends of anatomical features. We examined the variation in morphological and stem anatomical features of a widely distributed (2,200–5,300 m a.s.l.) Rhododendron lepidotum across elevation gradients in Langtang and Sagarmatha National Parks of Nepal Himalayas. Plant samples in each site were collected from three elevation bands (ca. 3,000, 4,000, and 5,000 m a.s.l.). In both study sites, all morphological features measured had their highest value at the lowest elevation and vice versa. Vessel density of basal stem increased but diameter and area of xylem vessels, and length of vessel element and fiber tracheids decreased as elevation increased. Similarly, height and the number of cells in uniseriate rays and height, width, area, and density of multiseriate rays also decreased toward the highest elevation. However, anatomical features of the ultimate branch did not show any distinct pattern with elevation. Morphological features showed more plasticity than anatomical features along the elevation gradients. Decreased plant height, individual leaf area, specific leaf area, and the existing trade-off relationship between vessel diameter and density could have supported a wide distribution of R. lepidotum in Nepal Himalayas.

Comparative wood anatomy of Korean Viburnum L. (Adoxaceae) and its taxonomic implication.

Comparative wood anatomy of Viburnum was carried out to understand the differences in wood features amongst the species which might be useful for taxonomic discrimination in the genus. Altogether, nine taxa belonging to five clades were investigated using a sliding microtome and light microscopy. The growth rings are well represented and earlywood and latewood are distinguishable in cross-section. Some of the important wood features include angular, oval and rounded vessels with scalariform perforation plates, opposite to scalariform inter-vessel pitting, rounded pits with slit-like apertures, thick-walled xylem tracheids with simple, rounded bordered pits, diffuse axial parenchyma, uni- and multiseriate rays, 2–4 cells wide. In general, there is a remarkable uniformity in the qualitative wood features in Viburnum species, although quantitative measurement showed some disparities. The most significant quantitative wood variables which might be useful for taxonomic groupings of the species comprise a frequency of vessels and rays, the diameter of the vessels and tracheids in the radial and tangential planes and height and width of rays in the tangential plane.

Türkiye’de Doğal ve Plantasyon Meşcerelerinde Yetişen Dar Yapraklı Dişbudak (Fraxinus angustifolia Vahl.) Ağaçlarının Bazı Odun Özellikleri

Ash wood is very important for forest products industry. Because of its fast growing property it was planting for severeal years. Wood quality may change with several factors which one of the important factor is site conditions. The aim of this study was to investigate the anatomical, physical properties and compression strength paralell to grain of natural and planted narrow leaved ash (Fraxinus angustifolia Vahl.) wood at different sites in Turkey. It was shown that there was a significant difference between natural and planted trees and between regions for all wood properties. Planted trees had higher density which had thicker double fiber cell wall, lower earlywood vessel frequency, higher and/or similar ray width, shorter earlywood vessels, lower multiseriate ray high number and length. The maximum oven-dry densities were 0.773 gr.cm-3 in Sinop and 0.719 gr.cm-3 in Adapazarı for planted trees. Higher shrinkage values were observed in denser planted trees. Planted trees exhibited higher compression strength parallel to grain (53.32 N.mm-2 in Adapazarı and 55.32 N.mm-2 in Sinop) than natural trees (51.02 N.mm-2 in Adapazarı and 50.05 N.mm- 2 in Sinop). As a result; planted NLA wood showed better wood properties except shrinkage values.

The occurrence and structure of radial sieve tubes in the secondary xylem of Aquilaria and Gyrinops

Abstract New observations of radial sieve tubes in the secondary xylem of two genera and four species of agarwood — Aquilaria sinensis, A. crasna, A. malaccensis and Gyrinops versteeghii (Thymelaeaceae) — are presented in this study. The earliest radial sieve tubes in Gyrinops are formed in the secondary xylem adjacent to the pith. The radial sieve tubes originate from the vascular cambium and develop in both uniseriate and multiseriate ray tissue. In addition to sieve plates in lateral and end walls, scattered or clustered minute sieve pores are localized in the lateral wall of radial sieve tubes. There is a direct connection between radial sieve tubes in ray tissue and axial sieve tubes in interxylary phloem strands (IP), such as (i) connection by bending of radial sieve tube strands, (ii) connection of two IP strands by an oblique bridge, and (iii) connection of two IP strands at a right angle. The average number of radial sieve tubes and interxylary phloem was found to be 1.7 per mm3 and 9.1 per mm2 in the secondary xylem. Considering the higher frequency of radial sieve tubes with the increasing thickness of the secondary xylem, the direct connections between radial and axial sieve tubes could play a significant role in assisting the translocation of metabolites in Aquilaria and Gyrinops.

Astroniumxylon, Schinopsixylon, andParametopioxylonn. gen. fossil woods from upper Cenozoic of Argentina: taxonomic revision, new taxon and new records

AbstractThis paper presents new descriptions of Anacardiaceae fossil woods from the Ituzaingó Formation (late Cenozoic) at the Toma Vieja, Curtiembre, and Arroyo El Espinillo localities, Argentina. We describe eight silicified woods assigned to four different species in three genera, one of which,Parametopioxylon crystalliferumn. gen. n. sp., is new. Similarities between these three genera and the six Anacardiaceae species previously recorded from the late Cenozoic in northeastern Argentina are investigated using multivariate analysis techniques (correspondence and cluster analysis). Our study is based on 33 characters scored for 17 fossil specimens (10AstroniumxylonBrea, Aceñolaza, and Zucol 2001; fiveSchinopsixylonLutz, 1979; and twoParametopioxylonn. gen.) and four extant species (Astronium balansaeEngl.,Astronium urundeuvaEngl.,Schinopsis balansaeEngl., andMetopiumsp.). Our main goal is to determine the wood anatomical features useful for distinguishing among these species. Results of the multivariate analyses support the previous classification whereSchinopsixylonis distinguished fromAstroniumxylonby having exclusively paratracheal axial parenchyma, ≥30% multiseriate rays, and multiseriate rays that are ≥5 cells wide and commonly 301–400 μm in height. Additionally, we propose thatSchinopsixylon heckiiLutz, 1979 is synonymous withS.herbstiiLutz, 1979. A diagnostic key for the fossil species studied is given. Wood anatomy of Anacardiaceae fossil woods from Argentina (late Cenozoic) suggests a warm, dry to semi-humid climate for this region, supporting previous studies.

New fossil woods of Fabaceae from El Bosque Formation (Eocene), Chiapas, Mexico

The diversity of Fabaceae in Mexico has a long geological history, and it is particularly rich in sediments from the Oligocene and Miocene. In this work, we describe the first record of two woods resembling ?Cercidoidea and Dialonoidea subfamilies from the Eocene of Chiapas. Both fossil woods have medium to large vessels, abundant paratracheal axial parenchyma, simple perforation plates, short vessel elements, alternate intervessel pits and non-vestured, vessel–ray pits with distinct borders and similar to intervessel pits in size and shape, homocellular (slightly heterocellular) multiseriate rays, prismatic chambered crystals in axial parenchyma cells and in fibers. These characteristics support the inclusion of both woods in Fabaceae. The identification of this new fossil genus (Tzotziloxylon) within Leguminosae, as well as other that have been described earlier from other Eocene localities of Mexico (e.g., Inga, Chamaecrista, and Senna), supports the hypothesis that some genera of this family probably evolved in North America instead of arriving by dispersal from Asia or Africa during the Eocene time.

The identification of Cryptocarya spp., Lauraceae in archeological charcoal

Archeological charcoal from hearths on three layers was analyzed to identify burnt woody taxa in terms of wood use in a larger study (Lennox et al. 2015 and 2017). A detailed anatomical study was made of a selection of Lauraceae charcoal by means of a modern reference collection and the Inside Wood database. The anatomical features were observed by means of reflective light microscopy. The IAWA features were arranged in a key so Cryptocarya spp. were identified amongst archeological charcoal. The distinguishing characteristics of Cryptocarya spp. are the multiseriate rays, ray cell type and vessel arrangement. Charcoal representing Cryptocarya cf. wyliei was identified in hearths from occupational layers, Brown under Yellow Ash (i), BYA2(i) and Spotty Camel, SPCA from ~58 ka, which implies the use of aromatic smoke during the Middle Stone Age; Ocotea bullata smoke is used medicinally in traditional herbal medicine.

Early Carboniferous lignophyte tree diversity in Australia: Woods from the Drummond and Yarrol basins, Queensland

Early Carboniferous (Mississippian) permineralized woods from Australia with multiseriate rays have been customarily assigned or compared to the European genus Pitus, despite the absence of information on their primary vascular anatomy. In the context of continuing work on the diversity of Late Devonian and Mississippian floras of Gondwana, we studied new silicified woods with secondary xylem similar to that of Pitus (multiseriate rays, araucarioid radial pitting) from two sedimentary basins of Queensland, Australia. In the Drummond Basin, three morphotypes of wood of Viséan age can be distinguished based on ray size in tangential section. Although this variation is similar to that observed between the various European species of Pitus, information on the primary vascular anatomy of the trees provided by three incomplete specimens excludes an affinity with Pitus for at least two taxa. In the Yarrol Basin, two well-preserved late Viséan trunks also have characters similar to Pitus but can be distinguished from that genus and other previously described Mississippian trees, in particular by the anatomy of their primary vascular system and departing leaf traces. They are assigned to a new genus, Ninsaria. Collectively, the new specimens from Queensland show that wood traditionally referred to “Pitus” from Australia actually belongs to several other types of trees that are not known from Europe or North America, indicating probable floristic provincialism between the Northern and Southern hemisphere floras at this time. These new fossils corroborate the existence of a global Mississippian diversification of (pro)gymnosperm trees already noted in Laurussia. They also indicate that the Mississippian floras of Australia were more diverse and complex than traditionally inferred.

Living Cells in Wood 3. Overview; Functional Anatomy of the Parenchyma Network

The very different evolutionary pathways of conifers and angiosperms are very informative precisely because their wood anatomy is so different. New information from anatomy, comparative wood physiology, and comparative ultrastructure can be combined to provide evidence for the role of axial and ray parenchyma in the two groups. Gnetales, which are essentially conifers with vessels, have evolved parallel to angiosperms and show us the value of multiseriate rays and axial parenchyma in a vessel-bearing wood. Gnetales also force us to re-examine optimum anatomical solutions to conduction in vesselless gymnosperms. Axial parenchyma in vessel-bearing woods has diversified to take prominent roles in storage of water and carbohydrates as well as maintenance of conduction in vessels. Axial parenchyma, along with other modifications, has superseded scalariform perforation plates as a safety mechanism and permitted angiosperms to succeed in more seasonal habitats. This diversification has required connection to rays, which have concomitantly become larger and more diverse, acting as pathways for photosynthate passage and storage. Modes of growth such as rapid flushing, vernal leafing-out, drought deciduousness and support of large leaf surfaces become possible, advantaging angiosperms over conifers in various ways. Prominent tracheid-ray pitting (conifers) and axial parenchyma/ray pitting to vessels (angiosperms) are evidence of release of photosynthates into conductive cells; in angiosperms, this system has permitted vessels to survive hydrologic stresses and function in more seasonal habitats. Flow in ray and axial parenchyma cells, suggested by greater length/width ratios of component cells, is confirmed by pitting on end walls of elongate cells: pits are greater in area, more densely placed, and are often bordered. Bordered pit areas and densities on living cells, like those on tracheids and vessels, represent maximal contact areas between cells while minimizing loss of wall strength. Storage cells in rays can be distinguished from flow cells by size and shape, by fewer and smaller pits and by contents. By lacking secondary walls, the entire surfaces of phloem ray and axial phloem parenchyma become conducting areas across which sugars can be translocated. The intercontinuous network of axial parenchyma and ray parenchyma in woods is confirmed; there are no “isolated” living cells in wood when three-dimensional studies are made. Water storage in living cells is reported anatomically and also in the form of percentile quantitative data which reveal degrees and kinds of succulence in angiosperm woods, and norms for “typically woody” species. The diversity in angiosperm axial and ray parenchyma is presented as a series of probable optimal solutions to diverse types of ecology, growth form, and physiology. The numerous homoplasies in these anatomical modes are seen as the informative results of natural experiments and should be considered as evidence along with experimental evidence. Elliptical shape of rays seems governed by mechanical considerations; unusually long (vertically) rays represent a tradeoff in favor of flexibility versus strength. Protracted juvenilism (paedomorphosis) features redirection of flow from horizontal to vertical by means of rays composed predominantly or wholly of upright cells, and the reasons for this anatomical strategy are sought. Protracted juvenilism, still little appreciated, occurs in a sizeable proportion of the world’s plants and is a major source of angiosperm diversification.