Osmundaceous Ferns Research Articles

Fossil evidence for sporeling development of a Mesozoic osmundaceous fern.

An anatomically preserved fossil fern sporeling has been discovered in a Lower Cretaceous marine concretion from Vancouver Island, British Columbia, Canada, providing an opportunity to characterize rhizome growth from an extinct species. The specimen was studied from serial transverse sections prepared by the cellulose acetate peel technique. The rhizome ranges from ~0.7 to 1.1 mm in diameter, has a sclerenchymatous pith, a stele that attains a dictyoxylic architecture, and sclerenchymatous outer cortex, features that are characteristic of osmundaceous rhizomes. Cauline xylem forms a medullated protostele or solenostele at some levels, but is dissected into discrete xylem bundles at others. Fronds diverge in a helical phyllotaxis, range up to 1.1 mm in greatest dimension, and have a C-shaped trace and outer cortex of sclerotic cells. Inside the sclerenchyma of the petioles are two lateral sclerotic strands and a sclerotic bundle adaxial to the trace. Together, these characters reveal the occurrence of a new species, Todea minutacaulis and provide evidence for developmental changes that occur in the rhizome as the sporeling increased in size. Small size of the specimen, medullated protostelic-dictyoxylic solenostelar vascular architecture, and incompletely sclerified cells apically reveal that osmundaceous sporeling development has remained constant since at least the Early Cretaceous. Together with Todea tidwellii and Osmunda vancouverensis that also are present in the Apple Bay flora, this sporeling documents the occurrence of a multispecies assemblage of osmundaceous ferns and demonstrates that the genus Todea was diversifying rapidly by the Early Cretaceous.

Revisiting the Late Cretaceous Parataxodium wigginsii flora from the North Slope of Alaska, a high-latitude temperate forest

Reinvestigation of a Late Cretaceous plant assemblage from along the Colville River on the North Slope of Alaska reveals both that the flora is far more diverse than previously suspected, and that many specimens are anatomically preserved. The flora includes one moss, an osmundaceous fern, one species of Ginkgo, the putative conifer leaf Pityophyllum, five species of cupressaceous conifers, five dicot leaf morphotypes, and one monocot. The cupressaceous remains heretofore have been interpreted as a single taxodioid/sequoioid conifer species, Parataxodium wigginsii Arnold and Lowther. However, reexamination of the fossils reveals five different morphologies of cupressaceous ovuliferous cones, and a wide range of intergrading leafy shoot morphologies. Peel sections show excellent internal anatomy for many of the cupressaceous conifer organs, as well the moss. These fossils characterize a high-latitude deciduous flora dominated by cupressoid conifer trees, with less common dicot and Ginkgo trees, and with ground cover that includes osmundaceous ferns, monocots, and dicranalean mosses. The increased diversity of disarticulated plant parts in the assemblage demonstrates that Parataxodium wigginsii is not nearly as well understood as widely believed, and that the genus and species concepts as currently defined may be based on organs from several cupressaceous conifers. This assemblage is an outstanding example of an unusual Late Cretaceous, high-latitude, Northern Hemisphere, mixed dicot-coniferous, cool temperate, deciduous forest that existed in total darkness for a significant period each year.

Plenasium xiei sp. nov. from the Cretaceous of Northeast China: Additional evidence for the longevity of osmundaceous ferns

AbstractA new species of the Osmundaceae, Plenasium xiei sp. nov., is herein described from the Cretaceous of Northeast China. The specimens examined here represent the earliest unequivocal record of the extant genus Plenasium in Eurasia based on fossil rhizomes. The rhizome consists of a central stem with a mantle of petiole bases and adventitious roots. The stem contains an ectophloic‐dictyoxylic siphonostele and a two‐layered cortex. The C‐shaped leaf trace bears two protoxylem bundles at the point of separation from the stele. The pith is heterogeneous. The parenchymatous inner cortex is thinner than the sclerenchymatous outer cortex. Lobed sclerenchyma bands occur at the adaxial sides of the stem xylem strands, in the concavity of the leaf trace, and along the adaxial side of the vascular bundles of the petiole base. In distal petiole portions, the sclerenchyma band splits into several groups in the transverse view. Sclerenchyma rings are heterogeneous with an abaxial sclerenchymatous arc of thick‐walled fibers. Numerous sclerenchyma strands of thick‐walled fibers appear in the petiolar inner cortex and the stipular wing. These fossils provide unambiguous evidence for the existence of subgenus Plenasium of modern Plenasium by at least the Late Cretaceous, demonstrating the longevity of this extant subgenus. Altogether the leaf and rhizome fossil records of Plenasium indicate that this genus was widely distributed across North America and Eurasia from the Early Cretaceous to the Early Cenozoic, followed by a range restriction to Eurasia in the Late Cenozoic. Extant Plenasium species are only known from East and Southeast Asia.

Stems of a New Osmundaceous Fern from the Middle Jurassic of Kursk Region, European Russia

New species of osmundaceous ferns, Osmundastrum gvozdevae sp. nov., is established on the basis of small coalified stems with preserved cellular structure, originated from the Upper Bathonian deposits of the Mikhailovskii Rudnik locality (Kursk Region, European Russia). Vascular tissues of the stem are represented by ectophloic dictyoxylic siphonostele; pith homogenous, comprising prosenchymatous cells only. Xylem of the leaf trace is endarch, with protoxylem strand, bifurcating when passes through the external part of an outer cortex. Leaf bases with stipular wings; their vascular bundles are horseshoe-shaped, with two sclerenchyma masses on the side of adaxial concavity. Sclerenchyma rings in the leaf bases are heterogeneous, thick-walled fibers form distinct abaxial arch and two lateral masses. The new species is provisionally assigned to the extant genus Osmundastrum C. Presl on the basis of the stem anatomical peculiarities.

(2683) Proposal to conserve the name Leptopteris C. Presl (Osmundaceae, Pteridophyta) against Leptopteris Brongn. (Fossil Plants)

Leptopteris C. Presl, Suppl. Tent. Pterid.: 70. 1845 (sero), nom. cons. prop. Typus: L. fraseri (Hook. & Grev.) C. Presl (Todea fraseri Hook. & Grev.). Leptopteris Brongn., Hist. Vég. Foss. 1: 149. 23 Nov 1829, nom. rej. prop. Typus: non designatus. Leptopteris Brongn. (Hist. Vég. Foss. 1: 149. 1829) non C. Presl (Suppl. Tent. Pterid.: 70. 1845) was recovered only recently when contributing to the International Fossil Plant Names Index (IFPNI; http://fossilplants.info/about), a recently initiated global registry of the scientific names of fossil plants, algae, fungi and prokaryotes traditionally covered by the International Code of Nomenclature for algae, fungi, and plants (Turland & al. in Regnum Veg. 159. 2018). As recorded in IFPNI, fossil Leptopteris Brongn. (non C. Presl) is based on foliage with no further description of fossil-species. Brongniart created the fossil-genus, providing a generic diagnosis in clavi in his sketch of the classification of fossil ferns and a single illustration (pl. 31, fig. 1), but evidently later abandoned it, since no fossil-species were described under this generic name. In his subsequent Histoire des végétaux fossiles (Part 4), published on 1 Feb 1830, nearly a year later, in a discussion of the fossil sphenopterid foliage, Brongniart admitted the resemblance between the fossil-species Sphenopteris nervosa Brongn. (Hist. Vég. Foss. 1: 174. 1830) and (sic!) “plusieurs espèces d’Adianthum (pl. XXXI, fig. 1); mais dans les Adianthum les folioles sont presque toujours pédicellées et plus espacées, et leur texture est plus mince qu'elle ne le paraît dans la plante fossile”. From this Brongniart's original comment we could conclude that it is possible that Leptopteris Brongn. with the adiantoid type of venation, demonstrated in the figure accompanying the original diagnosis, is no more than a fossil generic counterpart of extant Adiantum L. (Sp. Pl.: 1094. 1753): “distingue ces feuilles et permettraie d'en former un groupe distinct (Leptopteris), si on les retrouvait à l’état fossile” (Brongniart, l.c. 1830: 170). However, Leptopteris Brongn. became a “nomen oblitum & dubium” even in Brongniart's original monograph on fossil plants (though unfinished), with no further descriptions or illustrations. Unfortunately, no authentic originals have been found in Brongniart's collections (Muséum National d'Histoire Naturelle, Paris, France); judging from the single foliage illustration it could not be attributed with certainty to either the ferns or pteridosperms. In any case, the valid publication of Leptopteris cannot be questioned in terms of current nomenclatural rules, and this fossil-generic name is an obstacle to the continued use of its junior homonym, Leptopteris C. Presl (l.c.), for extant osmundaceous ferns. This nomenclatural situation, with Leptopteris validated on fossil material before publication of the widely known extant osmundaceous genus has been overlooked by all subsequent researchers on fern taxonomy (Bobrov in Bot. Zhurn. (Moscow & Leningrad) 52: 1609. 1962; Miller in Contr. Mus. Paleontol. Univ. Michigan 23: 105. 1971; Kramer in Kubitzki, Fam. Gen. Vasc. Pl. 1: 200. 1990; Yatabe in J. Pl. Res. 112: 397. 1999; Grimm & al. in Syst. Biol. 64: 396. 2014; Bomfleur & al. in PeerJ 5: e3433. 2017). The aim of the proposal is to fix the status quo, i.e., to legitimize the modern wide usage of the illegitimate later homonym Leptopteris C. Presl, with six extant recognized species aggregated in four series (Bobrov, l.c.), by conservation against its senior homonym, the fossil Leptopteris Brongn. Otherwise, a new name for the extant osmundaceous genus and their associated fossil forms based on foliage, cones and pollen would be required which would lead to destabilization of modern fern nomenclature by the necessary transfer of the species names of six extant and three fossil-species (two based on dispersed spores and one on fossil stems) into a new genus (no heterotypic generic synonyms are known). ABD, https://orcid.org/0000-0003-0089-5919 I thank John McNeill for suggestions on and corrections to the initial draft. It is a pleasure to thank Valentina Bublik (Fundamental Botanical Library of the National Institute of Carpology, Moscow) for bibliographic assistance. The research is a contribution to the Palaeoflora Europaea Project, Palaeoflora of Russia (Palaeoflora Rossica) Project (NOM-19-150) and The International Fossil Plant Names Index (IFPNI; http://fossilplants.info/).

Fossil flora of Middle Jurassic Grojec clays (southern Poland). Raciborski’s original material reinvestigated and supplemented. II. Pteridophyta. Osmundales

Abstract In the second part of the series dealing with the flora of the Grojec clays (Poland, Middle Jurassic), macroremains of Osmundales are introduced. The re-examined and supplemented material originates from three collections: specimens collected and described in Polish by Raciborski in 1894; specimens preliminarily described by Stur (1888), housed at the Geological Survey of Austria; and Raciborski’s still-unpublished material stored at the Institute of Botany of the Jagiellonian University. So far, 15 taxa of Cladophlebis have been described from the Osmundales of Grojec clays, and two species of Todites (Todea) and Osmundopsis (Osmunda) sturii. Detailed observations indicate that a large part of the material (12 taxa described by Raciborski) should be assigned to three widespread Jurassic species: Cladophlebis denticulata, C. haiburnensis, and C. roessertii. Cladophlebis aurita and C. bartonecii, created by Raciborski, should be retained. The occurrence of sterile and fertile fronds of Todites williamsonii (originally described as Todea williamsonis, Cladophlebis whitbiensis, and Cladophlebis solida) is confirmed for Grojec. Two species described by Raciborski (1894) required a change of generic names - Osmundopsis (Osmunda) sturii and Todites (Todea) princeps. This paper provides the taxonomical descriptions and considers the palaeoecology of 5 Cladophlebis species (C. aurita, C. denticulata, C. haiburnensis, C. roessertii, C. bartonecii) and other osmundaceous ferns such as Osmundopsis sturii, Todites williamsonii, and T. princeps.

Biotic interactions in an exceptionally well preserved osmundaceous fern rhizome from the Early Jurassic of Sweden

A remarkably well permineralized osmundaceous rhizome from the Early Jurassic of southern Sweden yields evidence of an array of interactions with other organisms in its immediate environment. These include epiphytism by a herbaceous heterosporous lycopsid; putative oribatid mite herbivory and detritivory (petiole and detritus borings and coprolites); potential pathogenic, saprotrophic or mycorrhizal interactions between fungi and the host plant and its epiphytes; parasitism or saprotrophy by putative peronosporomycetes; and opportunistic or passive mycophagy by oribatid mites evidenced by fungal spores in coprolites. A combination of abrupt burial by lahar deposits and exceedingly rapid permineralization by precipitation of calcite from hydrothermal brines facilitated the exquisite preservation of the rhizome and its component community of epiphytes, herbivores, saprotrophs and parasites. Ancient ferns with a rhizome cloaked by a thick mantle of persistent leaf bases and adventitious roots have a high potential for preserving macro-epiphytes and associated micro-organisms, and are especially promising targets for understanding the evolution of biotic interactions in forest understorey ecosystems.

Mesozoic Diversity of Osmundaceae: Osmundacaulis whittlesii sp. nov. in the Early Cretaceous of Western Canada

Premise of research. A distinctive new species of osmundaceous fern, based on a permineralized trunk from Lower Cretaceous deposits of Haida Gwaii (formerly the Queen Charlotte Islands) off the west coast of mainland Canada, provides additional data for addressing the Mesozoic diversity and the overall pattern of phylogeny for osmundaceous filicalean ferns.Methodology. The specimen was cut into segments and studied from both external morphology and anatomical sections prepared by the cellulose acetate peel technique. Microscope slides of sections were examined, and images were captured under transmitted light.Pivotal results. The fossil represents a new species of Osmundacaulis, which is only the third Northern Hemisphere representative of this predominantly Southern Hemisphere genus.Conclusions. Osmundacaulis whittlesii sp. nov. increases the Northern Hemisphere diversity of Cretaceous Osmundaceae, thus providing new data about Mesozoic diversity of the clade, potential sister-group relationships of crown-group Osmundaceae, and the overall pattern of phylogeny for Osmundaceae.

A specialized new species of Ashicaulis (Osmundaceae, Filicales) from the Jurassic of Liaoning, NE China

A new species of structurally preserved fern rhizome, Ashicaulis plumites (Osmundaceae, Filicales), is described from the Middle Jurassic Tiaojishan Formation in western Liaoning Province, NE China. The new species is characterized by a peculiar sclerenchyma mass in the petiolar vascular bundle concavity. This sclerenchyma mass varies from a linear-shape to a mushroom-like shape with a remarkable outward protuberance, which distinguishes the present new species from other Ashicaulis species. Such a protuberance is very rare among osmundaceous ferns, and should represent a unique type for sclerenchymatous tissue in the osmundaceous vascular bundle concavity. Recognition of the peculiar structure of this new fossil species enriches anatomical diversity of permineralized osmundaceous ferns, indicating that the family Osmundaceae might have experienced a remarkable diversification during the Middle Jurassic in NE China. The new species show anatomical similarities to Osmunda pluma Miller from the Palaeocene of North America. The occurrence of A. plumites in the Middle Jurassic of China provides a new clue for understanding the evolution of some members of the living subgenus Osmunda.

High-precision U–Pb geochronology and a new chronostratigraphy for the Cañadón Asfalto Basin, Chubut, central Patagonia: Implications for terrestrial faunal and floral evolution in Jurassic

The fluvial, lacustrine and tuffaceous sedimentary succession of the Cañadón Asfalto continental basin exposed in the Argentinean Chubut Province of central Patagonia preserves an extraordinary record of Jurassic fauna and flora that marks key events in the evolution of Dinosauria, early mammals and major South American plant groups. However, basin-wide correlation of the fossiliferous units is complicated by fault displacements, unconformities and repetitive lithofacies. New U–Pb analyses of zircon (CA-TIMS method) from five primary tuff beds interstratified with the lacustrine strata establish a new chronostratigraphic framework for the sedimentary and volcanic units of Cañadón Asfalto Basin, constraining ca. 33m.y. of depositional history and biotic evolution that spans nearly all three epochs of the Jurassic. Five major vertebrate- and plant-rich stratigraphic intervals have been identified, and are being actively investigated, that range in age from Pliensbachian to Kimmeridgian (or younger). Our combined biostratigraphic and high-precision geochronologic results indicate that the major faunal turnover of the sauropodomorph dinosaurs which led to the rise of the eusauropods took place in the Early Jurassic, earlier than previously recognized. Similarly, the first successful radiation of the ornithischian dinosaurs (heterodontosaurids), as well as the evolutionary diversifications of the araucarian conifers and the osmundaceous ferns, all occurred before the end of the Early Jurassic. The diverse palynofloral assemblage of the Cañadón Calcáreo Formation that was once considered to be early Cretaceous in age, is now entirely constrained to the Late Jurassic.

An osmundaceous rhizome with sterile and fertile fronds and in situ spores from the Jurassic of western Liaoning

A well-preserved permineralized osmundaceous fern was discovered from the Middle Jurassic Tiaojishan Formation of Beipiao, Liaoning Province, China. The rhizome is about 50 cm high and 35–41 cm in diameter and can be attributed to the genus Ashicaulis on the basis of its anatomy. The sterile pinnae are referable to Cladophlebis, the fertile pinnules are of the Todites type with in situ spores of the Osmundacidites type. Osmundaceous rhizomes have been found all over the world including the Jurassic strata of western Liaoning, China. Until now, however, no rhizomes have been reported to be organically connected with leafy organs. Although impressions and compressions of isolated osmundaceous sterile and fertile fronds are common, they were described under separate organ- or morpho-generic names, such as Todites and Cladophlebis. The new discovery provides an opportunity to study an osmundaceous fern in ‘whole plant concept’ to learn more about its morphology and structure, and the paleoclimatic and paleoenvironmental requrirements of this group.

A new species of osmundaceous fern rhizome, Ashicaulis macromedullosus sp. nov., from the Middle Jurassic, northern China

Ashicaulis macromedullosus sp. nov. (Osmundaceae) is described on the basis of one silicified rhizome, collected from the Middle Jurassic Tiaojishan Formation in Hebei, China. This specimen consists of a small, upright stem surrounded by frond bases, and adventitious roots. The stem consists of pith, xylem cylinder, a two-layered cortex and petiole bases. In cross section, the stem has a dictyoxylic xylem cylinder composed of 24–32 xylem strands separated by many leaf gaps with some incomplete leaf gaps. This species is characterized by continuous cylindrical phloem, absence of medullary traces in the pith, no sclerenchyma in leaf trace concavity, homogeneous cortical sclerenchyma, and one mass of sclerenchyma in each stipular wing. This is the third structurally preserved rhizome of Ashicaulis from the Mesozoic in northern China and adds to the knowledge of fern diversity in China. Northern Hemisphere species from the Jurassic have a tendency to larger stele diameter than comparable Mesozoic species in the Southern Hemisphere.

Identifying fern gametophytes using DNA sequences

AbstractIdentification of fern gametophytes is generally hampered by low morphological complexity. Here we explore an alternative: DNA‐based identification. We obtained a plastid rbcL sequence from a sterile gametophyte of unknown origin (cultivated for more than 30 years) and employed blast to determine its affinities. Using this approach, we identified the gametophyte as Osmunda regalis. To evaluate the robustness of this determination, and the usefulness of rbcL in differentiating among species, we conducted a phylogenetic analysis of osmundaceous fern sequences. Based on our results, it is evident that DNA‐based identification has considerable potential in exploring the ecology of fern gametophytes.

Ashicaulis woolfei n. sp.: additional evidence for the antiquity of osmundaceous ferns from the Triassic of Antarctica

Numerous small fern trunks and dispersed osmundaceous frond fragments occur within a Middle Triassic silicified peat near Fremouw Peak in the Transantarctic Mountains of Antarctica. These specimens form the basis of a new species of osmundaceous ferns that further helps to characterize the early Mesozoic vegetation of high latitude Gondwana. Ashicaulis woolfei n. sp. consists of small, upright trunks with a persistent armor of frond bases, adventitious roots, and vegetative frond parts. In cross section the trunks are ∼2.5 cm in diameter and include up to 45 frond bases. Stems range from 5 to 8 mm in diameter with a xylem cylinder of 8-9 xylem segments separated by leaf gaps. Phyllotaxy is variable, approaching 2/5 or 3/8, with 10-12 frond traces in the cortex. Stipes have parenchymatous, stipular wings that are usually devoid of sclerenchyma; fronds are pinnate with alternate-subopposite pinnatifid pinnules. Although the absence of fertile pinnules and sporangia precludes assigning the fossils to a living genus, this species demonstrates that ferns with stelar architecture and histology similar to Osmunda subgenus Osmundastrum (Osmundaceae) were present in the Southern Hemisphere by the mid-Triassic.

Osmunda cinnamomea (Osmundaceae) in the Upper Cretaceous of Western North America: Additional Evidence for Exceptional Species Longevity among Filicalean Ferns

The discovery of numerous anatomically preserved fossils in Upper Cretaceous sediments reveals that essentially modern osmundaceous ferns have inhabited southern Alberta, Canada, since the end of the Mesozoic. The Cretaceous fossils consist of small stems that are surrounded by leaf bases and adventitious roots. All of the features of the fossils fall within the ranges of variation for characters of living Osmunda cinnamomea L., and the fossils display all of the specifically diagnostic anatomical characters for this species. These include an ectophloic, dictyoxylic solenostele that lacks leaf gaps in the phloem, C‐shaped frond traces, frond bases with lateral stipular expansions, features of the endodermis, and disposition of sclerenchyma tissues in the stem and frond bases. A reexamination of extant specimens and of previously described fossils from Neogene and Paleocene deposits clarifies the range of variation for specifically diagnostic characters and reveals the more or less continuous presence of O. cinnamomea L. in western North America for at least 70 million years. This article provides an additional example of a well‐characterized fossil filicalean fern that can be confidently assigned to a species with living representatives. It is becoming increasingly clear that species longevity for homosporous pteridophytes can be far greater, and species turnover may be far lower, than expected from evolutionary models developed for flowering plants.

Structure of a near-polar latitude forest from the New Zealand Jurassic

A tidal platform at Curio Bay near the southernmost point of the South Island, New Zealand, preserves the petrified remains of an in situ Middle Jurassic forest. The forest grew close to the palaeo-polar circle, but data are not precise enough to tell on which side it lay. A mapped portion of the forest floor provides data on tree density and population structure, allowing comparison with recent forests and with records of other fossil forests. The forest has tree densities similar to many forests growing in low to mid-latitudes today; it appears to have had emergents projecting through a low canopy, and a well-developed undergrowth of smaller gymnosperms and osmundaceous ferns. No aspect of the forest structure uniquely distinguishes it from that of non-polar latitude forests. An extended discussion is given on reconstructing tree height from stump diameter. On the basis of this, a reinterpretation of the structure of an Early Cretaceous fossil forest from Alexander Island, Antarctica, is offered.

Millerocaulis richmondii sp. nov., an osmundaceous fern from Mesozoic strata near Little Swanport, Tasmania, Australia

A permineralised rhizome from Mesozoic strata south of Little Swanport, Tasmania, represents a new species of Millerocaulis (M. richmondii).Its stem is 6 x 7 mm across and is surrounded by adhering leaf bases with each having a stipular expansion typical of the Osmundaceae. The xylem of the ectophloic siphonostele comprising this stem is dissected by leaf gaps and consists of 14 xylem strands in its cylinder.Twenty leaf traces occur in a transverse section of its cortices. The xylem of its leaf traces and petiolar vascular strands is generally curved adaxially with a single protoxylem cluster being median on the trace. This proroxylem cluster bifurcates into two protoxylem groups immediately after leaving the stem and upon entering the petiole. The sclerotic ring of the petiole base is uniform in width and cell-wall thickness. A mass of sclerenchyma present in the adaxial concavity of the petiolar vascular strand expands at higher levels of the petiole until it fills the concavity of the strand and becomes immediately adjacent to the sclerotic ring. A large, round cellular mass of sclerenchyma occurs in the stipular expansions midway between their sclerotic rings and their tips. Millerocaulis richmondii is an additional species in the family Osmundaceae which was very abundant in Tasmania during mid-Mesozoic time.

A reappraisal ofPhyllopteroidesMedwell (Osmundaceae) and its stratigraphic significance in the Lower Cretaceous of eastern Australia

Four species of Phyllopteroides are present in the Lower Cretaceous of eastern Australia: P. laevis sp. nov., P. serrata sp. nov., P. dentata Medwell 1954a and P. lanceolata (Walkom) Medwell 1954b. The first three of these species occur in successive stratigraphic horizons in the Victorian Lower Cretaceous; they form a probable evolutionary lineage showing progressive changes in leaf morphology, particularly shape and dentation. Well-preserved osmundaceous fructifications (Cacumen expansa gen. et sp. nov.) occur closely associated with P. dentata leaves, strongly suggesting that Phyllopteroides is an osmundaceous fern. The Lower Cretaceous megafloral zonation of Douglas (1969) is revised by defining the zone boundaries as the first occurrence of the nominate Phyllopteroides species for each zone. This modified zonation can be correlated with the Lower Cretaceous microfloral zonation, and is applicable to Lower Cretaceous floras throughout eastern Australia.

The Root-Hairs, Cap, and Sheath of Azolla

Previous articleNext article FreeThe Root-Hairs, Cap, and Sheath of AzollaR. G. LeavittR. G. Leavitt Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 34, Number 6Dec., 1902 Article DOIhttps://doi.org/10.1086/328304 Views: 70Total views on this site Citations: 10Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:Hideo Yamasaki, Masahiro P. Ogura, Katsumi A. Kingjoe, Michael F. Cohen d-Cysteine-Induced Rapid Root Abscission in the Water Fern Azolla Pinnata: Implications for the Linkage between d-Amino Acid and Reactive Sulfur Species (RSS) in Plant Environmental Responses, Antioxidants 8, no.99 (Sep 2019): 411.https://doi.org/10.3390/antiox8090411Stephen McLoughlin, Benjamin Bomfleur Biotic interactions in an exceptionally well preserved osmundaceous fern rhizome from the Early Jurassic of Sweden, Palaeogeography, Palaeoclimatology, Palaeoecology 464 (Dec 2016): 86–96.https://doi.org/10.1016/j.palaeo.2016.01.044Peter W. Barlow The Root Cap: Cell Dynamics, Cell Differentiation and Cap Function, Journal of Plant Growth Regulation 21, no.44 (Apr 2003): 261–286.https://doi.org/10.1007/s00344-002-0034-z Ann Eastman , and R. L. Peterson Root Apex Structure in Regnellidium diphyllum (Marsileaceae), Botanical Gazette 146, no.11 (Oct 2015): 44–55.https://doi.org/10.1086/337499Thomas A. Lumpkin, Donald L. Plucknett Azolla: Botany, physiology, and use as a green manure, Economic Botany 34, no.22 (Apr 1980): 111–153.https://doi.org/10.1007/BF02858627B. E. S. Gunning, J. E. Hughes, A. R. Hardham Formative and proliferative cell divisions, cell differentiation, and developmental changes in the meristem of Azolla roots, Planta 143, no.22 (Jan 1978): 121–144.https://doi.org/10.1007/BF00387786R. Bloch Histological foundations of differentiation and development in plants, (Jan 1965): 146–188.https://doi.org/10.1007/978-3-642-50088-6_6R. Bloch Histological foundations of differentiation and development in plants, (Jan 1965): 146–188.https://doi.org/10.1007/978-3-662-36273-0_6 Laetitia Morris Snow The Development of Root Hairs, Botanical Gazette 40, no.11 (Oct 2015): 12–48.https://doi.org/10.1086/328644 Notes for Students, Botanical Gazette 38, no.33 (Sep 2015): 222–238.https://doi.org/10.1086/328546