Heterocellular Rays Research Articles

Anatomical conservatism in the wood and bark of the species-rich Byrsonimoid clade (Malpighiaceae)

Abstract The byrsonimoids include approximately 152 species of trees and shrubs native to the Neotropical region. The clade is monophyletic and consists of three genera: Byrsonima, Blepharandra, and Diacidia. Byrsonima woods are among the most well-known within the Malpighiaceae due to their economic importance. Nonetheless, here for the first time we explore the interspecific stem anatomical diversity of Byrsonima, its similarities and differences to Blepharandra and Diacidia, and how the previously proposed taxonomic circumscriptions for the genus Byrsonima are reflected or not in their wood and bark anatomy. Using a newly reconstructed phylogeny for the Malpighiaceae focusing on the clade Byrsonimoid and a broad selection of species, we conducted phylogenetic comparative analyses to determine how wood and bark traits have evolved across evolutionary time. Our results indicate stem anatomical homogeneity within the clade, particularly in wood traits. On one hand, the presence of septate fibres and prismatic crystals in the rays distinguishes Byrsonima from other members of the clade, but on the other hand, wood and bark traits do not support the classical infrageneric classifications for the genus. The bark in byrsonimoids displays the entire range of variation known for sclerenchyma in this tissue, from cells that can be considered true fibres to fibre-sclereids and typical true sclereids. Ancestral character state reconstructions revealed that radial arrangement, septate fibres, thin heterocellular rays, marginal parenchyma, and prismatic crystals are ancestral traits within the clade, with homoplasy common within the group. These observations demonstrate anatomical conservatism within the Byrsonimoid clade, which might be either related to their proposed recent diversification or a highly effective set of positively selected features.

Wood of Qualea from the Piedra Chamana in-situ fossil forest (late Middle Eocene, Peru) and the comparative wood anatomy of Vochysiaceae and Myrtaceae

Summary A wood from a late Middle Eocene in-situ fossil forest in northern Peru shows affinity with Qualea (Vochysiaceae), a genus of South American lowland tropical trees, based on features including vestured pits, aliform-confluent to banded paratracheal parenchyma, and homocellular rays. Additional features suggest adaptation to dry conditions. The fossil is named as a new species within Qualeoxylon (Q. lafila). Vochysiaceae and sister-group Myrtaceae share features unique to Myrtales (vestured pits, intraxylary phloem) or common in the order (vessels generally solitary and in >1 diameter class, heterocellular rays) but in other ways are clearly differentiated. Vochysiaceae has narrow to very wide vessels with elaborated axial parenchyma and lacks most characters considered less specialized such as scalariform perforations. Myrtaceae generally has vessels with vasicentric tracheids, usually exclusively solitary, very narrow to wide, and often diagonally arranged, and includes taxa with less to more specialized features. Woods with elaborated paratracheal parenchyma and vessels wide to very wide occur in wet tropical forest environments in both families Erisma, Vochysia and Qualea/Ruizterania (Vochysiaceae) in the Neotropics and Syzygium (Myrtaceae) in the Asian tropics. The Eucalyptus spp. dominating open forests in Australia have typical myrtaceous features (including vasicentric tracheids) plus homocellular rays, whereas the eucalypt clade Angophora + Corymbia, occurring mainly in the northern, monsoonal regions of Australia, has both vasicentric tracheids and aliform to banded axial parenchyma. The fossil is an early record for Vochysiaceae and adds to indications that Vochysiaceae and sister-group Myrtaceae showed significant diversification by the late Paleogene.

Anatomía de la madera de Magnolia rzedowskianaVázquez, Domínguez & Pedraza, especie endémica de la Sierra Madre Oriental, México

Introduction: Magnolia rzedowskianaVázquez, Domínguez & Pedraza is a tree species endemic to the cloud forest of the Sierra Madre Oriental; its scanty (distributed) and isolated populations are considered at danger of extinction.Objective: To describe the microscopic anatomical characteristics of M. rzedowskiana wood to contribute to the biological knowledge of this species.Materials and methods: Wood samples were determined by a non-destructive method, extracting two growth cores from five adult trees in each of the four sampling sites located in Chilijapa and Zotictla in Hidalgo, La Yesca in Querétaro and ejido La Trinidad in San Luis Potosí. Cores were sectioned into subsamples to elaborate fixed preparations from tangential, transversal and radial cuts. Characteristics were identified using an optical microscopy and described according to IAWA (International Association of Wood Anatomists) criteria.Results and discussion: Growth zones, diffuse porosity, solitary and multiple radial pores in intermediate arrangement between radial and tangential; scalariform perforation plate and libriform fibers; diffuse and scanty paratracheal and apotracheal axial parenchyma; biseriate rays combined with triserial, uniseriate and heterocellular rays composed of procumbent cells with a row above and below of marginal square cells with oil bodies. The wood is distinguished by mesomorphism and resistance to drought.Conclusion: The anatomical description of M. rzedowskiana is a contribution to biological knowledge. From an economic point of view, this wood has potential use to produce pulp for paper.

Warm and humid Trans-Himalaya during the late Miocene: plant fossil evidence

Neogene fossil records from the Indus Basin sedimentary rocks (IBSR), deposited in the Indus Tsangpo Suture Zone (ITSZ), are very rare, but are important to understand the history of plant diversity and paleoclimate in the Himalaya. We report fossil wood ascribed to Ebenoxylon siwalicus Prakash from late Miocene sediments of the Karit Formation belonging to ITSZ. The anatomical details of the fossil wood, such as small to medium-sized vessels occluded with tyloses, scanty paratracheal to diffuse-in-aggregate axial parenchyma, 1–3 seriate homo to heterocellular rays, bordered intervessel pits with lenticular apertures and simple perforations, suggest its close affinity with Diospyros Linnaeus of the family Ebenaceae. Further anatomical details suggest a close resemblance with extant D. ehretioides Don and D. macrophylla Blume. The present fossil, along with previously known fossil records of Lagerstroemia (Lythraceae) and palms, indicate that the Trans-Himalaya was warm and humid during the late Miocene, quite different from the modern cool and dry climate in the study area.

Cretaceous Lauraceae wood from El Rosario, Baja California, Mexico

A new wood type for the Baja California Cretaceous adds to the plant diversity so far known for the area where gymnosperms seem to be dominant. It was collected near El Rosario, Baja California, from rocks of the Rosario Formation, in a sedimentary sequence that comprises ca. 1200 m of non-marine to deep marine sediments from Upper Campanian to Lower Danian age. The wood is characterized by having semiring porous growth rings, predominantly radial multiples of 2–7 with occasional clusters and some solitary vessels, simple perforation plates, alternate intervascular pits, oval to large elliptical vessel element-ray pits with reduced borders, septate thin-walled fibers, 1–4 seriate heterocellular rays, scares paratracheal, vasicentric and marginal parenchyma and oil cells associated with ray parenchyma. All these characters are found in Lauraceae, however, none of the extant taxa of the family have all these characters and even among fossil woods the characters in the Baja California material are better described only among the diverse Laurinoxylon, but vessel grouping, growth ring type, absence of marginal parenchyma, and slightly thicker rays suggest the presence of a new taxon, Rosarioxylon bajacaliforniensis Cevallos-Ferriz, Catharina & Kneller. By the end of the Cretaceous the family formed part of the plant community that represents a western extension of vegetation types more completely described from areas in the margins of the southern limits of the Western Interior Sea. The new taxon is proposed to highlight anatomical differences and geographic isolation from similar taxa and further suggests a large distribution of Lauraceae in what appears to be conifer dominated communities.

Ficoxylon fusiforme (Moraceae), a New Species from the Upper Cretaceous Nubian Sandstone, Southern Egypt

A new species of Ficoxylon Kaiser (Moraceae) is described from the Upper Cretaceous Nubian Sandstone, Aswan area, southern Egypt. The new species, Ficoxylon fusiforme, is the third report of a Cretaceous wood attributed to Ficoxylon worldwide. The two other Cretaceous records, F. cretaceum Schenk and ?F. sp. of Krausel, are also from Egypt. Ficoxylon species are common in the Tertiary, from the Palaeocene to the Pliocene. An emended generic diagnosis is proposed for Ficoxylon, which was erected in 1880 with few details. The new species is compared with the 18 currently recognized species of Ficoxylon/Ficus; it is distinguished by a combination of characters: predominantly solitary, few, relatively wide vessels; axial parenchyma bands 3–8 cells wide; 2–7 seriate, spindle-shaped, closely spaced, and slightly heterocellular rays; thin-walled, nonseptate fibers. Comments are made on the Egyptian fossil remains of Moraceae and on all Egyptian Cretaceous wood taxa reported to date. Preliminary biogeographic and climatic implications are given.

Climbing since the early Miocene: The fossil record of Paullinieae (Sapindaceae).

Paullinieae are a diverse group of tropical and subtropical climbing plants that belong to the soapberry family (Sapindaceae). The six genera in this tribe make up approximately one-quarter of the species in the family, but a sparse fossil record limits our understanding of their diversification. Here, we provide the first description of anatomically preserved fossils of Paullinieae and we re-evaluate other macrofossils that have been attributed to the tribe. We identified permineralized fossil roots in collections from the lower Miocene Cucaracha Formation where it was exposed along the Culebra Cut of the Panama Canal. We prepared the fossils using the cellulose acetate peel technique and compared the anatomy with that of extant Paullinieae. The fossil roots preserve a combination of characters found only in Paullinieae, including peripheral secondary vascular strands, vessel dimorphism, alternate intervessel pitting with coalescent apertures, heterocellular rays, and axial parenchyma strands of 2–4 cells, often with prismatic crystals. We also searched the paleontological literature for other occurrences of the tribe. We re-evaluated leaf fossils from western North America that have been assigned to extant genera in the tribe by comparing their morphology to herbarium specimens and cleared leaves. The fossil leaves that were assigned to Cardiospermum and Serjania from the Paleogene of western North America are likely Sapindaceae; however, they lack diagnostic characters necessary for inclusion in Paullinieae and should be excluded from those genera. Therefore, the fossils described here as Ampelorhiza heteroxylon gen. et sp. nov. are the oldest macrofossil evidence of Paullinieae. They provide direct evidence of the development of a vascular cambial variant associated with the climbing habit in Sapindaceae and provide strong evidence of the diversification of crown-group Paullinieae in the tropics by 18.5–19 million years ago.

WOOD ANATOMICAL STUDIES REVEAL TAXONOMIC RELATIONSHIPS, ENVIRONMENTAL INFLUENCE AND PULP POTENTIAL IN FOUR TAXA OF Mussaenda (RUBIACEAE) GROWN IN NIGERIA

Current study was carried out to assess the taxonomic, ecological significance, and paper making potential of four taxa of Mussaenda L. (Rubiaceae) viz., M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ through wood anatomical studies. Each of the taxa was collected from its natural region of provenance in two different ecological zones (Derived Savanna and Tropical Rainforest) of Nigeria. Observations from different planes of sections were made and wood maceration was carried out for fibre morphology. Absent to scanty paratracheal axial parenchyma, septate fibres, pitted vessels, storied heterocellular rays, and simple perforation plates were common features in all taxa. However, multiseriate and wider rays distinguished the exotic species from the indigenous species, and the semi-diffuse porous wood pattern was a unique feature in M. ‘Dona Aurora’. Quantitative data showed considerable variations in case of fibre lengths among the four taxa i.e. M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ and was recorded 0.80 ± 0.02 µm, 0.70 ± 0.05 µm, 0.65 ± 0.03 µm and 0.64 ± 0.04 µm respectively. These observations showed that all species belong to Wood Type II of Rubiaceae and support their inclusion in the Tribe Mussaendeae and Order Ixoroideae. The influence of environmental factors was evident in the significant elongation of wood vessels of samples collected from more humid areas, but with no significant effect on their paper-making potential. More so, M. “Doña Aurora”, had general scores, would be most suitable for pulp and paper making.

WOOD ANATOMICAL STUDIES REVEAL TAXONOMIC RELATIONSHIPS, ENVIRONMENTAL INFLUENCE AND PULP POTENTIAL IN FOUR TAXA OF Mussaenda (RUBIACEAE) GROWN IN NIGERIA

Current study was carried out to assess the taxonomic, ecological significance, and paper making potential of four taxa of Mussaenda L. (Rubiaceae) viz., M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ through wood anatomical studies. Each of the taxa was collected from its natural region of provenance in two different ecological zones (Derived Savanna and Tropical Rainforest) of Nigeria. Observations from different planes of sections were made and wood maceration was carried out for fibre morphology. Absent to scanty paratracheal axial parenchyma, septate fibres, pitted vessels, storied heterocellular rays, and simple perforation plates were common features in all taxa. However, multiseriate and wider rays distinguished the exotic species from the indigenous species, and the semi-diffuse porous wood pattern was a unique feature in M. ‘Dona Aurora’. Quantitative data showed considerable variations in case of fibre lengths among the four taxa i.e. M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ and was recorded 0.80 ± 0.02 µm, 0.70 ± 0.05 µm, 0.65 ± 0.03 µm and 0.64 ± 0.04 µm respectively. These observations showed that all species belong to Wood Type II of Rubiaceae and support their inclusion in the Tribe Mussaendeae and Order Ixoroideae. The influence of environmental factors was evident in the significant elongation of wood vessels of samples collected from more humid areas, but with no significant effect on their paper-making potential. More so, M. “Doña Aurora”, had general scores, would be most suitable for pulp and paper making.

WOOD ANATOMICAL STUDIES REVEAL TAXONOMIC RELATIONSHIPS, ENVIRONMENTAL INFLUENCE AND PULP POTENTIAL IN FOUR TAXA OF Mussaenda (RUBIACEAE) GROWN IN NIGERIA

Current study was carried out to assess the taxonomic, ecological significance, and paper making potential of four taxa of Mussaenda L. (Rubiaceae) viz., M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ through wood anatomical studies. Each of the taxa was collected from its natural region of provenance in two different ecological zones (Derived Savanna and Tropical Rainforest) of Nigeria. Observations from different planes of sections were made and wood maceration was carried out for fibre morphology. Absent to scanty paratracheal axial parenchyma, septate fibres, pitted vessels, storied heterocellular rays, and simple perforation plates were common features in all taxa. However, multiseriate and wider rays distinguished the exotic species from the indigenous species, and the semi-diffuse porous wood pattern was a unique feature in M. ‘Dona Aurora’. Quantitative data showed considerable variations in case of fibre lengths among the four taxa i.e. M. elegans, M. erythrophylla, M. philippica var. aurorae, and M. ‘Dona Aurora’ and was recorded 0.80 ± 0.02 µm, 0.70 ± 0.05 µm, 0.65 ± 0.03 µm and 0.64 ± 0.04 µm respectively. These observations showed that all species belong to Wood Type II of Rubiaceae and support their inclusion in the Tribe Mussaendeae and Order Ixoroideae. The influence of environmental factors was evident in the significant elongation of wood vessels of samples collected from more humid areas, but with no significant effect on their paper-making potential. More so, M. “Doña Aurora”, had general scores, would be most suitable for pulp and paper making.

Phylogenetic placement of enigmatic Astianthus (Bignoniaceae) based on molecular data, wood and bark anatomy

Background: Astianthus is a monospecific arborescent genus of Bignoniaceae that occur in the Pacific Coast of central Mexico and northern Central America, where it grows in dense populations along riversides. Its phylogenetic placement has remained controversial since Astianthus has unusual morphological characters such as a four-loculed ovary, and simple, pulvinate, verticillate leaves.
 Methods: Here we used three plastid markers ndh F, rbc L, and trn L-F, wood, and bark anatomical data to investigate the phylogenetic placement of Astianthus and assign it to one of Bignoniaceae’s main clades.
 Results: Our molecular phylogenetic analyses indicated that Astianthus belongs in tribe Tecomeae s.s. , where other charismatic Neotropical Bignoniaceae genera such as Campsis and Tecoma are currently placed. Wood and bark anatomy support this placement, as Astianthus reunites a unique combination of features only known from members of Tecomeae s.s. , such as storied axial parenchyma, the co-occurrence of homo- and heterocellular rays, septate fibers, and scattered phloem fibers in the bark.
 Conclusions: The placement of Astianthus within Tecomeae s.s. provides further support to previous proposals for the Neotropical origin of this Pantropical tribe.

The first report of an ‘evergreen Castanopsis type’ wood (Fagaceae) for the Late Miocene–Early Pliocene of Europe (Bulgaria, Blagoevgrad Graben)

In the present article, the establishment of the species Castanopsis: C. bulgarica Mantzouka, Ivanov, and Bozukov is proposed after the study of a new fagaceous fossil wood stem discovered in 2016 from a new Late Miocene to Early Pliocene plant fossiliferous locality east of Boboshevo town, south‐west Bulgaria. A detailed palaeoxylotomical study of the fossil wood revealed characteristics of the ‘evergreen Quercus type’ (e.g. the gradual porosity of the vessels, the existence of two types of rays: uniseriate and multiseriate aggregate, the oval shape of the solitary vessels outline, the occurrence of tracheids) as well as heterocellular compound‐aggregate rays, typical for Castanopsis. Similarities and differences of the anatomical characteristics/features of the studied specimen with the descriptions of the fossil representatives of Fagaceae (Quercoxylon, Lithocarpoxylon, and Castanopsis) along with its botanical affinities are discussed. A taxonomic list of the Bulgarian fossil fagaceous record of the same age and their nearest living relatives is provided. Emended xylotomical keys with the addition of Castanopsis have been created. Moreover, the presence of evergreen Castanopsis species with heterocellular rays of two distinct sizes in the fossil record of the ‘evergreen oak woods’ is supported.

Wood anatomy of South African Meliaceae: evolutionary and ecological implications

AbstractWood structure in seven South African species of Ekebergia, Nymania, Trichilia and Turraea (Meliaceae) was studied and compared with data for other genera of the subfamily Melioideae to elucidate phylogenetic relationships and pathways of trait evolution in this group and to clarify the ecological significance of some wood characters. Non-septate fibres, the presence of crystals in axial parenchyma and relatively wide (> triseriate) heterocellular rays are the ancestral conditions for Melioideae. A loss of crystals confirms the monophyly of the clade embracing tribe Turraeeae and Pterorhachis. Uniseriate rays are synapomorphic for the Turraeeae+Trichilieae clade with secondary gains of wider rays in the Nymania+Pterorhachis lineage and in some species of Turraea and Trichilia. A close relationship between Nymania and Pterorhachis was also confirmed by their similarity in having small intervessel pits. Trichilia is distinctive by its homocellular rays made of square and upright cells. The close affinity between Ekebergia and Quivisianthe is confirmed by their similar composition of rays that consist only of procumbent cells. Nymania capensis and Turraea obtusifolia share narrower (< 50 µm) and more numerous (> 70 per mm2) vessel lumina than other species; these are adaptive features for their habitat.

The fossil genus Aextoxicoxylon (Magnoliopsida) in the Upper Cretaceous Puntudo Chico Formation, Chubut Province, Argentina

A new fossil dicot wood recovered from the Upper Cretaceous Puntudo Chico Formation is here identified as a representative of the fossil genus Aextoxicoxylon. Differences with the type species support the recognition of a new species, Aextoxicoxylon kawasianus sp. nov. This new taxon is characterized by having indistinct growth rings, solitary vessels, diffuse porosity, perforation plates scalariform with high number of bars, and heterocellular rays. All these features are typical of primitive woods according to Baileyan trends. Furthermore, anatomy of the wood, and the presence of fungal hyphae in vessels, suggests non-seasonal and probably warm and humid climate, which agrees with previous proposals for the Puntudo Chico Formation and other units of similar ages. Aextoxicoxylon is a new element previously not recognized in the Late Cretaceous to Danian floristic assemblages that seem to have been linked to the Kawas Sea, a shallow sea that developed in Patagonia at the end of the Cretaceous.

Development of successive cambia and formation of secondary xylem in Suaeda nudiflora and S. fruticosa (Amaranthaceae s.l.)

Amaranthaceae s.l. and its allied families like Amaranthaceae s.s., Chenopodiaceae s.s. and Phytolaccaceae s.s. are always debated in the literature about their pattern of secondary growth; when their stem diameter increases by forming successive cambia. In the present study, development of successive cambia and differentiation of its derivatives was investigated in Suaeda fruticosa and S. nudiflora (Amaranthaceae s.l.). After primary growth, the first complete ring of cambium was formed by the successive cambium due to failure in the development of interfascicular cambium between adjacent vascular bundles. The first ring of successive cambium initiated from the parenchymatous cells (pericyclic derivatives) external to the protophloem. This newly formed cambium was functionally bidirectional and produced secondary xylem centripetally and phloem centrifugally. Subsequent renewal of cambium was observed as small segments instead of complete ring. They interconnect with existing cambium and form anastomosing network. Due to the renewal of small sectors, the secondary phloem formed by earlier cambial segments became enclosed within the secondary xylem and conjunctive tissue. Formation of vessels and sieve elements were found confined only to few fusiform cells while rest of the cambial sector exclusively produced conjunctive tissue on either side. The secondary xylem formed in the beginning of successive rings of xylem remained rayless while thick stems showed presence of heterocellular rays with several cells in height and width. Accumulation of starch along with the presence of nuclei in the xylem fibres even after deposition of the secondary wall is consistent feature in both the species.

Wood evolution: Baileyan trends and Functional traits in the fossil record

ABSTRACTWe revisited questions about changes in the incidences of functional wood anatomical traits through geologic time and compared the incidences of these traits in the fossil record with modern wood anatomical diversity patterns in order to test classical (“Baileyan”) and more recent ecophyletic hypotheses of xylem evolution. We contrast patterns through time for tropical and higher (paleo)latitudes. Data are from the InsideWood database. There are striking differences between woods from high and mid latitudes versus tropical (paleo)-latitudes. At temperate and subtropical latitudes (Laurasia and high latitude Gondwana), the epoch by epoch time series supports the Baileyan transformation series of vessel-bearing woody angiosperms (basal woody angiosperms and eudicots): “primitive” features such as scalariform perforations, exclusively solitary vessels, apotracheal diffuse parenchyma and heterocellular rays abound in the Cretaceous and become much less frequent in the Cenozoic, especially post-Eocene. In contrast, in the paleotropics hardly any changes occur in the incidences – each epoch has an equally “modern” spectrum of wood anatomical attributes. Although climatic gradients from the poles to the equator were less steep in the Cretaceous than in the late Cenozoic, the wood anatomical differences between mid-high latitude woods and tropical woods were much more pronounced in the Cretaceous than in later epochs. This seeming paradox is discussed but we cannot resolve it.We suggest that tropical conditions have accelerated xylem evolution towards greater hydraulic efficiency (simple perforations), biological defense and hydraulic repair (elaborate paratracheal parenchyma patterns) as evidenced by late Cretaceous tropical latitude woods having near modern incidences of almost all traits. At higher paleolatitudes of both the Northern and Southern Hemisphere “ancestral” features such as scalariform perforations were retained in cooler and frost-prone regions where they were not selected against in mesic habitats because of lower demands on conductive efficiency, and could even be advantageous in trapping freeze-thaw embolisms. The fossil wood record remains too incomplete for testing hypotheses on the wood anatomy of the earliest angiosperms. The low incidence of so-called “xerophobic” woods sensu Feild with scalariform perforations with numerous (over 40) closely spaced bars in the Cretaceous tropical fossil record is puzzling. At higher paleolatitudes such woods are common in the Cretaceous.Ring porosity, an indicator of seasonal climates and deciduousness, occurs at low levels in the Cretaceous and Paleogene at higher paleolatitudes only, and reaches modern levels in the Miocene. In Neogene and Recent temperate Northern Hemisphere, wide vessels are virtually restricted to ring-porous woods. In the tropics, there is a low incidence of ring porosity throughout all epochs.The fossil record indicates that ecophysiological adaptation to tropical or temperate conditions was already evident in the Cretaceous with considerable latitudinal differences.

A new species of Carlquistoxylon from the Early Cretaceous of Patagonia (Chubut province, Argentina): the oldest record of angiosperm wood from South America

ABSTRACT An angiospermous wood from the Lower Cretaceous (upper Albian) of the Cerro Barcino Formation, Chubut Group, central Patagonia, Argentina, is described. Its estimated minimum diameter is 40 cm and it is significant as the oldest known angiosperm wood for South America. It has indistinct growth ring boundaries, vessels solitary and in radial multiples, simple perforation plates, alternate intervessel pits, vessel-ray parenchyma pits oval to horizontally elongated, heterocellular rays, non-septate fibres, axial parenchyma absent, and abundant tyloses. Because this Albian wood has non-septate fibres we assign it to Carlquistoxylon, even though it has a general combination of characters similar to that of Paraphyllanthoxylon, which has septate fibres. The number of vessels per radial multiple, vessel tangential diameter and frequency, vessel-ray parenchyma pitting, and absence of axial parenchyma distinguish the fossil described here from the only previously known species of Carlquistoxylon: Carlquistoxylon nacimientense; therefore, a new species is erected. Because of the close similarities between this new specimen and Paraphyllanthoxylon species, comparisons with all the species included in both genera are provided. Systematic affinities for this wood are discussed considering previous discussions for both Paraphyllanthoxylon and Carlquistoxylon affinities. As the oldest described angiosperm wood in South America to date, this specimen provides critical information on the diversity and growth habit of Cretaceous angiosperms from the Southern Hemisphere.

More Malpighiales: Woods of Achariaceae and/or Salicaceae from the Deccan Intertrappean beds, India

AbstractThe families Achariaceae and Salicaceae (Malpighiales) are characterized by wood anatomical ranges that partly overlap. Formerly these families were treated together in the polyphyletic Flacourtiaceae and a much more narrowly circumscribed Salicaceae. Here we attribute two recently collected fossil woods from the Deccan Intertrappean Beds to the clade that contain these two families, i.e., the Parietal Clade of the Malpighiales. The new genus Elioxylon shares features with several extant genera of Achariaceae and Salicaceae, but does not completely match with any of them. A new record of Hydnocarpoxylon indicum Bande & Khatri is a good match for extant Hydnocarpus Gaertn. (Achariaceae). Elioxylon and Hydnocarpoxylon share an absence of parenchyma, the presence of septate fibres and 1–3 seriate heterocellular rays with long uniseriate margins consistent with Achariaceae and Salicaceae. Elioxylon has mixed simple and scalariform perforations, whereas Hydnocarpxylon has exclusively scalariform perforations. Other Deccan fossils formerly attributed to “Flacourtiaceae” in the literature are critically discussed and mostly excluded from Achariaceae and Salicaceae. Elioxylon and Hydnocarpoxylon from the Maastrichtian ‐ Danian of India are the oldest fossil records of the Parietal Clade of the Malpighiales. With their occurrence on the Indian plate during its northward journey from Gondwana to Laurasia, these fossils provide further support for an ‘out‐of‐India’ hypothesis for Achariaceae and/or Salicaceae. “Baileyan trends” in vessel perforation plate and vessel grouping evolution are apparent in the phylogeny of the Parietal Clade.

Trabeculae and Al-accumulation in the wood cells of Melastomataceae species from Brazilian savanna

Family Melastomataceae is an important component of the Brazilian Cerrado flora, inhabiting different environments from those with well-drained soils to swamp soil sites. Several members of this family are recognized as aluminum (Al)-accumulating. We studied the wood anatomy of six species of Melastomataceae (Miconia albicans (Sw.) Triana, M. fallax DC., M. chamissois Naudin, M. ligustroides (DC.) Naudin, Microlepis oleaefolia (DC.) Triana, Rhynchanthera dichotoma DC.), growing in different environments of Cerrado, exploring the occurrence of trabeculae and Al-accumulation sites. We processed the material following the usual techniques in wood anatomy and histochemistry. We used a chrome azurol-S spot-test in fresh material to detect Al-accumulation. The common features were diffuse porosity, vessel elements with simple perforation plates and vestured pits, abundant parenchyma-like fiber bands and septate fibers, axial parenchyma scanty to vasicentric, and heterocellular rays. The presence of trabeculae in vessel elements, septa in parenchyma cells, and aluminum in the G-layer of the gelatinous fiber walls, in the septa of fibers, in cambial initials and derivatives cell walls, and in the vacuole of ray cells are recorded for the first time for Melastomataceae. The results of this study indicate an additional role for gelatinous fibers in Al-accumulation, and offer a new perspective on Al-compartmentalization in the wood cells from Cerrado species.

Structure and ontogeny of the fissured stems of Callaeum (Malpighiaceae)

Stem ontogeny and structure of two neotropical twining vines of the genus Callaeum are described. Secondary growth in Callaeum begins with a typical regular cambium that gradually becomes lobed as a result of variation in xylem and phloem production rates in certain portions of the stem aligned with stem orthostichies. As development progresses, lignified ray cells of the initially formed secondary xylem detach on one side from the adjacent tissues, forming a natural fracture that induces the proliferation of both ray and axial nonlignified parenchyma. At the same time, parenchyma proliferation takes place around the pith margin and generates a ring of radially arranged parenchyma cells. The parenchyma generated in this process (here termed disruptive parenchyma) keeps dividing throughout stem development. As growth continues, the parenchyma finally cleaves the lignified axial parts of the vascular system into several isolated fragments of different sizes. Each fragment consists of xylem, phloem and vascular cambium and is immersed in a ground matrix of disruptive parenchyma. The cambium present in each fragment divides anticlinally to almost encircle each entire fragment and maintains its regular activity by producing xylem to the centre of the fragment and phloem to the periphery. Additionally, new cambia arise within the disruptive parenchyma and produce xylem and phloem in various polarities, such as xylem to the inside and phloem to the outside of the stem, or perpendicularly to the original cambium. Unlike the very distinctive stem anatomical architecture resulting from this cambial variant in Callaeum, its secondary xylem and phloem exhibit features typical of lianas. These features include very wide conducting cells, abundant axial parenchyma, high and heterocellular rays and gelatinous fibres.