Kathleen Pigg | Arizona State University (original) (raw)

Papers by Kathleen Pigg

Journal of the Botanical Research Institute of Texas

Donald J. Pinkava is best known for his application of cytogenetics in unraveling the complex int... more Donald J. Pinkava is best known for his application of cytogenetics in unraveling the complex interspecific hybridization in the prickly pear genus Opuntia Mill. in the southwestern United States extending down into northern and central Mexico. Using cytogenetics, Pinkava delimited species boundaries within Opuntia for taxonomic treatments. His work on Opuntia in the Chihuahuan Desert led to later comprehensive contributions in the Flora of North America and the Flora of Arizona that include opuntias not only in the Southwest but in every US state. Pinkava's systematic knowledge, as reflected in his taxonomic treatments provided the basic scientific framework needed for ongoing conservation of Cactaceae in the Southwest to the present day. Interestingly, the starting point for all of Pinkava's contributions in Cactaceae began with his initial studies of Asteraceae as a student of T. Richard Fisher at The Ohio State University (OSU), an institution with longstanding research ...

International Journal of Plant Sciences, 2020

In this conclusion to the volumes celebrating the contributions of Gar W. Rothwell, students refl... more In this conclusion to the volumes celebrating the contributions of Gar W. Rothwell, students reflect on his influence on their intellectual development; an interdisciplinary coauthor on working with him; and colleagues on his contributions to paleobotany, morphology, and the broader plant phylogenetic and scientific world.

International Journal of Plant Sciences, 2018

Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessil... more Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessile bulbils, both covered partially by a persistent spathe, are described from the latest early Eocene Republic flora of north-central Washington. They are associated with an individual specimen of a single bulb with attached roots, and two small flower buds that appear to represent the same plant. The morphology of these fossils closely resembles that of certain bulb-forming monocots, such as some species of the onion genus Allium and other members of Amaryllidaceae. Methodology. Compression-impression fossils preserved in a lacustrine shale were uncovered from the rock matrix to reveal morphological details and were photographed with LM. Specimens were compared morphologically with extant material of related plants, and resulting images were processed minimally with Adobe Photoshop. Pivotal results. Specimens demonstrate an organography that is quite similar to that of modern onions and related forms. To our knowledge, this is the first description of plants showing a combination of bulbils and florets (representing asexual and sexual reproduction) among Paleogene plants. It also represents one of few reports among the fossil record of monocot plants similar to members of Amaryllidaceae. Conclusions. Scapes bearing flowers and bulbils within a spathe similar to those of some modern Amaryllidaceae, associated flower buds, and a root-producing bulb indicate the presence of a distinctive monocot plant in the Republic flora of the latest early Eocene Okanogan Highlands, northeastern Washington. Along with other Republic plants with distinctive morphological features indicative of temperate floras (leaf dimorphism, possible hybridization), these fossils suggest that bulbil-and flower-bearing monocots with a combined asexual and sexual reproductive strategy were already well established among plants of Paleogene.

Review of Palaeobotany and Palynology, 1998

Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been ... more Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been recovered from the middle Eocene Princeton chert (Allenby Formation) of British Columbia, Canada. Specimens were studied using a modified cellulose acetate peel technique using hydrofluoric acid. Diplopanax eydei Stockey, LePage et Pigg sp. nov. has fruits with endocarps up to 11 mm long and 10 mm in diameter that have a smooth stone surface, a single locule that is U-shaped in cross section, and a germination valve that extends nearly the full length of the fruit. An epicarp (exocarp + mesocarp) composed of thin-walled parenchymatous cells, 1.2–1.5 mm thick, is preserved on one specimen. Remnants of an apical disc with possible perianth scars are seen in three specimens. The endocarp is composed of interlocking fibers with scattered resin ducts and vascular tissue that parallels the edges of the valve. Seed integuments consist of a single external layer of large cells with brown contents and an inner zone of two to four thin-walled cells of smaller diameter lacking contents. Numerous septate fungal hyphae are usually present in the integumentary layers. These fruits represent the first reported fossils of the genus Diplopanax Handel-Mazzetti, and the northernmost known mastixioids in North America. The fruits are compared to those of other living and fossil mastixioids including Mastixicarpum Chandler and add to our knowledge of the diversity and distribution of the North American mastixioids during the Tertiary.

Natural history collections provide a wealth of temporal and spatial data about biological organi... more Natural history collections provide a wealth of temporal and spatial data about biological organisms of the present and the past. These collections can be used in many novel waysto support hands-on experiences that illustrate fundamental core science concepts for undergraduate education. As part of NSF-RCN “AIM-UP!” (Advancing Integration of Museums into Undergraduate Programs, http://www.aim-up.org/) we are developing hands-on educational modules on plant paleobiodiversity using Pennsylvanian-aged calcium carbonate permineralizations, known as coal balls. Coal balls are found along the margins of coal seams and are known from numerous localities in the North American Appalachian, Illinois and Midcontinent Basins, as well as Carboniferous basins in England, Russia, the European continent and China. They have been studied extensively, both taxonomically and ecologically, by paleobotanists and provide rich anatomical details of the plants that inhabited the Carboniferous coal swamps. ...

Review of Palaeobotany and Palynology, 1991

Inflorescences, flowers, and immature or abortive, mature and senescent fruits of Prmcetonia alle... more Inflorescences, flowers, and immature or abortive, mature and senescent fruits of Prmcetonia allenbyens& Stockey are described from the permineralized plants of the Princeton chert of southern British Columbia. Anatomical similarities of the reproductive structures, foral receptacles, fruiting axes and pollen morphology allow the identification of these varied reproductive organs in the same taxon. Inflorescences are racemes bearing at least thirteen attached, helically arranged flowers. Flowers are three-, four-and five-carpellate and syncarpous at the base. Bisexual flowers with two sepals, four or five petals and elongate, tetrathecal anthers contain psilate, pentacolpate pollen. Fruits are three-, four-or five-loculate capsules with complete septa, more than forty seeds per locule, and show loculicidal dehiscence. Seeds are anatropous, exarillate with abundant perisperm. The outer integument is represented by a palisade of elongate sclereids underlain by an inner integument of rectangular thin-walled cells. Seed anatomy resembles that in the Nymphaeaceae, but seed shape and lack of an operculum differ from nymphaeaceous taxa. This combination of reproductive characters is unknown among extant angiosperms, suggesting that these remains may represent an extinct family of aquatic Magnoliidae.

International Journal of Plant Sciences, 2006

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact

International Journal of Plant Sciences, 1994

Anatomical studies of several thousand specimens of Eorhiza arnoldii Robison and Person rhizomes ... more Anatomical studies of several thousand specimens of Eorhiza arnoldii Robison and Person rhizomes and their attached organs have added significantly to our knowledge of these Middle Eocene, semiaquatic dicotyledonous plants from the Princeton chert. Anatomical structure of Eorhiza was studied through serial sections on cellulose acetate peels. In order to establish the growth habit for these plants, individual axes were mapped as to their three-dimensional positions in the chert matrix. Plants grew from an extensive sympodial rhizome system similar to many living monocots and exhibited subopposite branching. Branches gave rise to rhizome sympodia or to branches bearing small scale-leaves. The architecture of Eorhiza conforms to the Tomlinson Model proposed by Halle, Oldeman, and Tomlinson. Leaves are ensiform, equitant, unifacial (isobilateral), and monocot-like with a large central lacuna. Rhizomes show typical dicot stelar anatomy. The presence of an aerenchymatous cortex and the plants' association with freshwater animal remains and representatives of known aquatic plant families, such as Nymphaeaceae, support an aquatic habitat for Eorhiza. The presence of rhizomes that produce roots bearing secondary and tertiary roots indicates in situ preservation of extensive rhizome systems at least 41 cm in length. A reconstruction of the vegetative body of Eorhiza is presented and a hypothesis offered concerning the attachment of reproductive structures to these plants.

International Journal of Plant Sciences, 2011

Bulletin of Geosciences, 2010

floras. Krassilov et al. deal with Russian/North American floristic interchange, and Collinson et... more floras. Krassilov et al. deal with Russian/North American floristic interchange, and Collinson et al. focus on the significance of exceptional preservation. An additional paper by Kvaček & Wilde describes new representatives of the European Eocene Malvaceae. The Paleogene is a pivotal interval of time for both plant evolution and the development of plant communities. The plant fossil record of the Paleogene provides the evidence of vegetation responses in previous greenhouse worlds as well as recording the development of key taxa and vegetation types found in temperate regions today. Therefore, it seemed both timely and useful to have included a symposium entitled "Paleogene floras and global change events" in the 7 th European Palaeobotany-Palynology Congress in Prague during September 2006 (Kvaček & Sakala 2007). This collection of six papers represents expanded and updated treatments of seven of the eight papers presented in that symposium. Aspects of two presentations (on Messel Oil Shales and the Insect Limestone) have been combined in one paper. The eighth paper (on the Paleocene-Eocene thermal maximum at Cobham, UK) was already destined for publication elsewhere (Collinson et al. 2009). Using Dieter Mai's 'Florenkomplex' system as a framework, Zlatko Kvacek describes the stratigraphic and geographic distribution of European Paleogene floras. He then groups them by vegetation type and provides the first large scale, tentative, yet critically evaluated, map of European Paleogene vegetation. Mikhail Akhmetiev reviews the Paleogene floras of Russia and northern Kazakhstan, bringing together a valuable English language summary of the vegetation and its response to climate and seaway changes across latitudes ranging up to the Arctic circle. He provides palaeogeographic maps documenting localities and key indicator taxa for the fossil floras. Valentin Krassilov, Tatiana Kodrul & Natalia Maslova discuss floristic interchange and continuity between eastern Asia and western North America through the Beringia connection. They focus on selected taxa including conifers of the Cupressaceae (including a new species); extinct relatives of the Platanaceae (platanoids) and Trochodendron and Cercidiphyllum (trochodendrocarpoids); and on various aquatic plants. The major floras from North America are discussed by Melanie DeVore & Kathleen Pigg in two papers (Late Palaeocene to Early Eocene, and Middle and Late Eocene to Oligocene). They consider vegetation response to climate change and emphasise the importance of incorporating information from basinal and depositional settings into vegetation interpretation. The paper by Margaret Collinson, Steve Manchester, Volker Wilde and Peta Hayes emphasizes the unique contribution made by exceptional preservation to our understanding of Paleogene plants and plant-animal interactions. They focus on a comparative study of fruit and seed floras from two examples-the middle Eocene oil-shales of Messel, Germany and the latest Eocene Insect Limestone of the UK. This collection of papers on the Paleogene history of floras and vegetation will be of interest to those studying fossil faunas, modern floras and the systematics of extant plants, and the future response of plants to climate change. Palaeobiologists working with mammals, birds and insects will gain easily accessible reviews and summaries of the vegetational framework in which Paleogene animals lived. Systematists working with extant plant groups will gain a better understanding of the plant evolutionary and biogeographic events of the Paleogene and how they shaped the current plant groups under study today. The Paleogene provides climate researchers with analogues to how modern plants and plant communities may respond to elevated temperatures and carbon dioxide levels. Coupling what is known about when major global change events occurred during the Paleogene, with a better understanding of the evolutionary and community histories of plants, will lead to a clearer picture of how key plants that define communities, as well as the communities themselves, respond to global change.

Canadian Journal of Botany, 1993

Paleomyrtinaea princetonensis gen. et sp.nov. Pigg, Stockey & Maxwell is described from the Middl... more Paleomyrtinaea princetonensis gen. et sp.nov. Pigg, Stockey & Maxwell is described from the Middle Eocene Princeton Chert of British Columbia, Canada. Anatomically preserved fruits are berries up to 1.6 × 0.78 cm with a fleshy fruit wall that consists of a three-layered pericarp. The exocarp is composed of a uniseriate epidermis of tabular cells and an outer hypodermis of small cells and the mesocarp is aerenchymatous. Some seeds are invested in a pulpy endocarp. The seeds are campylotropous, 1.8 mm long and 1.6 mm wide, and contain a curved embryo cavity about 1.5 mm long and 0.64 mm wide. Four distinct integumentary zones can be recognized, an outermost zone two to three cells thick of tangentially elongate cells, a second zone, constituting the bulk of the integument, of small, isodiametric cells, a third zone of uniseriate, columnar cells that extends into the germination valve, and an innermost zone of five to six layers of tangentially elongate cells. The genus is also represe...

Annals of the Missouri Botanical Garden, 1992

The evolution of the isoetalean lycopsids spans much of the history of vascular plants, from Late... more The evolution of the isoetalean lycopsids spans much of the history of vascular plants, from Late, (or possibly Middle), Devonian to the current day genus Isoetes. The best known fossil members of this group are the arborescent lepidodendrids that dominated the Late Carboniferous coal swamps. Simpler unbranched isoetaleans with elongate stems also predated, coexisted with, and postdated the coal swamp trees, extending well into the Mesozoic. Whereas certain synapomorphies such as stigmarian rootlets, bipolar growth and secondary tissues unite the clade, other features characterize smaller subgroups of differing age, growth form and possibly, evolutionary lineage. Although some of these features are well known for plants of given time periods, particularly the Carboniferous, trends in character evolution have never been adequately documented for the group as a whole. A better understanding of such trends throughout the isoetalean fossil record could be valuable in distinguishing evolutionary lineages from convergence. It is interesting that several morphological characters of modern Isoetes are present as early as the Triassic: monolete microspores, sunken sporangia and elaborate ligules with glossopodia occur within elongatestemmed Triassic forms. The dominant plant habit of modern Isoetes, a reduced cormose form that lacks appreciable stem elongation, originated at least by the Jurassic and typifies late Mesozoic and Cenozoic isoetaleans.

American Journal of Botany, 2005

The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern No... more The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern North America, and one in western Asia. Mature infructescences are studied to provide anatomical, morphological, and micromorphological details, some of which are newly recognized. Homology is suggested between extrafloral spinose processes of L. formosana and L. acalycina, braid-like ornamentation of L. styraciflua, and broad intercarpellate areas of L. orientalis. Morphology, position, number, and the presence of similar structures in the closely related Hamamelidaceae s.s. support their derivation from sterile flowers. Morphological cladistic analysis using 43 characters supports the monophyly of Liquidambar with Altingia as its sister. The matK analysis contrastingly places Altingia sister to the L. acalycina-L. formosana clade, rendering Liquidambar paraphyletic. Discordance between morphological and matK data sets may result from both different rates of morphological evolution and convergence. Several similarities between Altingia and L. acalycina are symplesiomorphic in the morphological cladistic analysis. Microaltingia apocarpela, from the Cretaceous of eastern North America, documents the earliest known fossil divergence within Altingiaceae. The Miocene Liquidambar changii of western North America is sister to a clade of extant Liquidambar species. Consideration of this fossil evidence reveals complex intercontinental biogeographic disjunctions in Altingiaceae.

American Journal of Botany, 2008

American Journal of Botany, 1987

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact

American Journal of Botany, 2007

Botanical Gazette, 1986

The genus Microspermopteris is characterized as a small lyginopterid pteridosperm with a pentarch... more The genus Microspermopteris is characterized as a small lyginopterid pteridosperm with a pentarch protostele, irregular cortical ridges, and multicellular trichomes. We describe the frond architecture and vari ability among axillary branches previously unknown for the genus. Fronds are small and delicate, exhibiting three orders of branching. Clasping V-shaped petioles produce primary pinnae alternately to suboppositely from adaxial projections. Primary pinnae in turn produce secondaries that bear two-, three-, or four-lobed ultimate laminar pinnules. Pinnules reconstructed from serial sections are morphologically similar to Sphenopteris-\ike compressions; however, the overall frond is reduced in size and complexity. While some axillary branches produce secondary xylem, others are composed entirely of primary tissues. Some axillary branches produce scalelike leaves in a tight helix; distally, immature buds are surrounded by flattened bud scales. Although Microspermopteris shows similarities to Heterangium in stelar and cortical anatomy, the two taxa are distinct. Microspermopteris is interpreted as a delicate, scrambling vine, liana, or shrublike plant in contrast to the more robust lyginopterids Lvginopteris, Schopfiastrum, and Heterangium.

Review of Palaeobotany and Palynology, 1991

The Middle Eocene Princeton chert from southern British Columbia represents one of the richest kn... more The Middle Eocene Princeton chert from southern British Columbia represents one of the richest known assemblages of permineralized Tertiary plants. Affinities with modern aquatic angiosperms, anatomical modifications for the aquatic habit and associated fresh water faunal elements support the interpretation of some components of the Princeton chert as in situ aquatic plants. Among these are fossil plants with affinities to the extant Nymphaeaceae (Allenbya), Araceae (KeratospermaL Alismataceae (Heleophyton), Cyperaeeae/Juncaceae (Ethela) and Lythraceae (Decodon). Anatomical modifications include aerenchyma in vegetative tissues (Eorhiza, Dennstaedtiopsis, Heleophyton and Uhlia), the thin-walled tracheary elements without prominent secondary wall thickenings and the presence of protoxylem lacunae surrounded by a ring of cells with thickened inner walls (Heleophyton). Seeds that share morphological features with extant aquatics are characterized by a palisade layer, operculum, external mucilage, small amounts of endosperm and abundant perisperm. Associated faunal elements include turtle bones in the peat matrix and freshwater fish at the top of the section. In situ preservation of these aquatic forms is supported by the presence of rooted axes, the large number of plant organs of the same type and preservation of complete flowers, delicate tissues and organic connections allowing for whole plant reconstruction.

Journal of the Botanical Research Institute of Texas

We dedicate this volume to our friend, mentor, and colleague who gave us so generously of his tim... more We dedicate this volume to our friend, mentor, and colleague who gave us so generously of his time, encyclopedic knowledge, wisdom, good humor, and patience. Dr. Pinkava mentored 35 students as chair or co-chair, including seven Ph.D. students, many of whom have launched their own academic careers (see list of graduate students at the end). He published generously with his students on Cactaceae, the Flora of Arizona and documenting new chromosome counts for both (see bibliography below).

Journal of the Botanical Research Institute of Texas

Donald J. Pinkava is best known for his application of cytogenetics in unraveling the complex int... more Donald J. Pinkava is best known for his application of cytogenetics in unraveling the complex interspecific hybridization in the prickly pear genus Opuntia Mill. in the southwestern United States extending down into northern and central Mexico. Using cytogenetics, Pinkava delimited species boundaries within Opuntia for taxonomic treatments. His work on Opuntia in the Chihuahuan Desert led to later comprehensive contributions in the Flora of North America and the Flora of Arizona that include opuntias not only in the Southwest but in every US state. Pinkava's systematic knowledge, as reflected in his taxonomic treatments provided the basic scientific framework needed for ongoing conservation of Cactaceae in the Southwest to the present day. Interestingly, the starting point for all of Pinkava's contributions in Cactaceae began with his initial studies of Asteraceae as a student of T. Richard Fisher at The Ohio State University (OSU), an institution with longstanding research ...

International Journal of Plant Sciences, 2020

In this conclusion to the volumes celebrating the contributions of Gar W. Rothwell, students refl... more In this conclusion to the volumes celebrating the contributions of Gar W. Rothwell, students reflect on his influence on their intellectual development; an interdisciplinary coauthor on working with him; and colleagues on his contributions to paleobotany, morphology, and the broader plant phylogenetic and scientific world.

International Journal of Plant Sciences, 2018

Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessil... more Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessile bulbils, both covered partially by a persistent spathe, are described from the latest early Eocene Republic flora of north-central Washington. They are associated with an individual specimen of a single bulb with attached roots, and two small flower buds that appear to represent the same plant. The morphology of these fossils closely resembles that of certain bulb-forming monocots, such as some species of the onion genus Allium and other members of Amaryllidaceae. Methodology. Compression-impression fossils preserved in a lacustrine shale were uncovered from the rock matrix to reveal morphological details and were photographed with LM. Specimens were compared morphologically with extant material of related plants, and resulting images were processed minimally with Adobe Photoshop. Pivotal results. Specimens demonstrate an organography that is quite similar to that of modern onions and related forms. To our knowledge, this is the first description of plants showing a combination of bulbils and florets (representing asexual and sexual reproduction) among Paleogene plants. It also represents one of few reports among the fossil record of monocot plants similar to members of Amaryllidaceae. Conclusions. Scapes bearing flowers and bulbils within a spathe similar to those of some modern Amaryllidaceae, associated flower buds, and a root-producing bulb indicate the presence of a distinctive monocot plant in the Republic flora of the latest early Eocene Okanogan Highlands, northeastern Washington. Along with other Republic plants with distinctive morphological features indicative of temperate floras (leaf dimorphism, possible hybridization), these fossils suggest that bulbil-and flower-bearing monocots with a combined asexual and sexual reproductive strategy were already well established among plants of Paleogene.

Review of Palaeobotany and Palynology, 1998

Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been ... more Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been recovered from the middle Eocene Princeton chert (Allenby Formation) of British Columbia, Canada. Specimens were studied using a modified cellulose acetate peel technique using hydrofluoric acid. Diplopanax eydei Stockey, LePage et Pigg sp. nov. has fruits with endocarps up to 11 mm long and 10 mm in diameter that have a smooth stone surface, a single locule that is U-shaped in cross section, and a germination valve that extends nearly the full length of the fruit. An epicarp (exocarp + mesocarp) composed of thin-walled parenchymatous cells, 1.2–1.5 mm thick, is preserved on one specimen. Remnants of an apical disc with possible perianth scars are seen in three specimens. The endocarp is composed of interlocking fibers with scattered resin ducts and vascular tissue that parallels the edges of the valve. Seed integuments consist of a single external layer of large cells with brown contents and an inner zone of two to four thin-walled cells of smaller diameter lacking contents. Numerous septate fungal hyphae are usually present in the integumentary layers. These fruits represent the first reported fossils of the genus Diplopanax Handel-Mazzetti, and the northernmost known mastixioids in North America. The fruits are compared to those of other living and fossil mastixioids including Mastixicarpum Chandler and add to our knowledge of the diversity and distribution of the North American mastixioids during the Tertiary.

Natural history collections provide a wealth of temporal and spatial data about biological organi... more Natural history collections provide a wealth of temporal and spatial data about biological organisms of the present and the past. These collections can be used in many novel waysto support hands-on experiences that illustrate fundamental core science concepts for undergraduate education. As part of NSF-RCN “AIM-UP!” (Advancing Integration of Museums into Undergraduate Programs, http://www.aim-up.org/) we are developing hands-on educational modules on plant paleobiodiversity using Pennsylvanian-aged calcium carbonate permineralizations, known as coal balls. Coal balls are found along the margins of coal seams and are known from numerous localities in the North American Appalachian, Illinois and Midcontinent Basins, as well as Carboniferous basins in England, Russia, the European continent and China. They have been studied extensively, both taxonomically and ecologically, by paleobotanists and provide rich anatomical details of the plants that inhabited the Carboniferous coal swamps. ...

Review of Palaeobotany and Palynology, 1991

Inflorescences, flowers, and immature or abortive, mature and senescent fruits of Prmcetonia alle... more Inflorescences, flowers, and immature or abortive, mature and senescent fruits of Prmcetonia allenbyens& Stockey are described from the permineralized plants of the Princeton chert of southern British Columbia. Anatomical similarities of the reproductive structures, foral receptacles, fruiting axes and pollen morphology allow the identification of these varied reproductive organs in the same taxon. Inflorescences are racemes bearing at least thirteen attached, helically arranged flowers. Flowers are three-, four-and five-carpellate and syncarpous at the base. Bisexual flowers with two sepals, four or five petals and elongate, tetrathecal anthers contain psilate, pentacolpate pollen. Fruits are three-, four-or five-loculate capsules with complete septa, more than forty seeds per locule, and show loculicidal dehiscence. Seeds are anatropous, exarillate with abundant perisperm. The outer integument is represented by a palisade of elongate sclereids underlain by an inner integument of rectangular thin-walled cells. Seed anatomy resembles that in the Nymphaeaceae, but seed shape and lack of an operculum differ from nymphaeaceous taxa. This combination of reproductive characters is unknown among extant angiosperms, suggesting that these remains may represent an extinct family of aquatic Magnoliidae.

International Journal of Plant Sciences, 2006

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact

International Journal of Plant Sciences, 1994

Anatomical studies of several thousand specimens of Eorhiza arnoldii Robison and Person rhizomes ... more Anatomical studies of several thousand specimens of Eorhiza arnoldii Robison and Person rhizomes and their attached organs have added significantly to our knowledge of these Middle Eocene, semiaquatic dicotyledonous plants from the Princeton chert. Anatomical structure of Eorhiza was studied through serial sections on cellulose acetate peels. In order to establish the growth habit for these plants, individual axes were mapped as to their three-dimensional positions in the chert matrix. Plants grew from an extensive sympodial rhizome system similar to many living monocots and exhibited subopposite branching. Branches gave rise to rhizome sympodia or to branches bearing small scale-leaves. The architecture of Eorhiza conforms to the Tomlinson Model proposed by Halle, Oldeman, and Tomlinson. Leaves are ensiform, equitant, unifacial (isobilateral), and monocot-like with a large central lacuna. Rhizomes show typical dicot stelar anatomy. The presence of an aerenchymatous cortex and the plants' association with freshwater animal remains and representatives of known aquatic plant families, such as Nymphaeaceae, support an aquatic habitat for Eorhiza. The presence of rhizomes that produce roots bearing secondary and tertiary roots indicates in situ preservation of extensive rhizome systems at least 41 cm in length. A reconstruction of the vegetative body of Eorhiza is presented and a hypothesis offered concerning the attachment of reproductive structures to these plants.

International Journal of Plant Sciences, 2011

Bulletin of Geosciences, 2010

floras. Krassilov et al. deal with Russian/North American floristic interchange, and Collinson et... more floras. Krassilov et al. deal with Russian/North American floristic interchange, and Collinson et al. focus on the significance of exceptional preservation. An additional paper by Kvaček & Wilde describes new representatives of the European Eocene Malvaceae. The Paleogene is a pivotal interval of time for both plant evolution and the development of plant communities. The plant fossil record of the Paleogene provides the evidence of vegetation responses in previous greenhouse worlds as well as recording the development of key taxa and vegetation types found in temperate regions today. Therefore, it seemed both timely and useful to have included a symposium entitled "Paleogene floras and global change events" in the 7 th European Palaeobotany-Palynology Congress in Prague during September 2006 (Kvaček & Sakala 2007). This collection of six papers represents expanded and updated treatments of seven of the eight papers presented in that symposium. Aspects of two presentations (on Messel Oil Shales and the Insect Limestone) have been combined in one paper. The eighth paper (on the Paleocene-Eocene thermal maximum at Cobham, UK) was already destined for publication elsewhere (Collinson et al. 2009). Using Dieter Mai's 'Florenkomplex' system as a framework, Zlatko Kvacek describes the stratigraphic and geographic distribution of European Paleogene floras. He then groups them by vegetation type and provides the first large scale, tentative, yet critically evaluated, map of European Paleogene vegetation. Mikhail Akhmetiev reviews the Paleogene floras of Russia and northern Kazakhstan, bringing together a valuable English language summary of the vegetation and its response to climate and seaway changes across latitudes ranging up to the Arctic circle. He provides palaeogeographic maps documenting localities and key indicator taxa for the fossil floras. Valentin Krassilov, Tatiana Kodrul & Natalia Maslova discuss floristic interchange and continuity between eastern Asia and western North America through the Beringia connection. They focus on selected taxa including conifers of the Cupressaceae (including a new species); extinct relatives of the Platanaceae (platanoids) and Trochodendron and Cercidiphyllum (trochodendrocarpoids); and on various aquatic plants. The major floras from North America are discussed by Melanie DeVore & Kathleen Pigg in two papers (Late Palaeocene to Early Eocene, and Middle and Late Eocene to Oligocene). They consider vegetation response to climate change and emphasise the importance of incorporating information from basinal and depositional settings into vegetation interpretation. The paper by Margaret Collinson, Steve Manchester, Volker Wilde and Peta Hayes emphasizes the unique contribution made by exceptional preservation to our understanding of Paleogene plants and plant-animal interactions. They focus on a comparative study of fruit and seed floras from two examples-the middle Eocene oil-shales of Messel, Germany and the latest Eocene Insect Limestone of the UK. This collection of papers on the Paleogene history of floras and vegetation will be of interest to those studying fossil faunas, modern floras and the systematics of extant plants, and the future response of plants to climate change. Palaeobiologists working with mammals, birds and insects will gain easily accessible reviews and summaries of the vegetational framework in which Paleogene animals lived. Systematists working with extant plant groups will gain a better understanding of the plant evolutionary and biogeographic events of the Paleogene and how they shaped the current plant groups under study today. The Paleogene provides climate researchers with analogues to how modern plants and plant communities may respond to elevated temperatures and carbon dioxide levels. Coupling what is known about when major global change events occurred during the Paleogene, with a better understanding of the evolutionary and community histories of plants, will lead to a clearer picture of how key plants that define communities, as well as the communities themselves, respond to global change.

Canadian Journal of Botany, 1993

Paleomyrtinaea princetonensis gen. et sp.nov. Pigg, Stockey & Maxwell is described from the Middl... more Paleomyrtinaea princetonensis gen. et sp.nov. Pigg, Stockey & Maxwell is described from the Middle Eocene Princeton Chert of British Columbia, Canada. Anatomically preserved fruits are berries up to 1.6 × 0.78 cm with a fleshy fruit wall that consists of a three-layered pericarp. The exocarp is composed of a uniseriate epidermis of tabular cells and an outer hypodermis of small cells and the mesocarp is aerenchymatous. Some seeds are invested in a pulpy endocarp. The seeds are campylotropous, 1.8 mm long and 1.6 mm wide, and contain a curved embryo cavity about 1.5 mm long and 0.64 mm wide. Four distinct integumentary zones can be recognized, an outermost zone two to three cells thick of tangentially elongate cells, a second zone, constituting the bulk of the integument, of small, isodiametric cells, a third zone of uniseriate, columnar cells that extends into the germination valve, and an innermost zone of five to six layers of tangentially elongate cells. The genus is also represe...

Annals of the Missouri Botanical Garden, 1992

The evolution of the isoetalean lycopsids spans much of the history of vascular plants, from Late... more The evolution of the isoetalean lycopsids spans much of the history of vascular plants, from Late, (or possibly Middle), Devonian to the current day genus Isoetes. The best known fossil members of this group are the arborescent lepidodendrids that dominated the Late Carboniferous coal swamps. Simpler unbranched isoetaleans with elongate stems also predated, coexisted with, and postdated the coal swamp trees, extending well into the Mesozoic. Whereas certain synapomorphies such as stigmarian rootlets, bipolar growth and secondary tissues unite the clade, other features characterize smaller subgroups of differing age, growth form and possibly, evolutionary lineage. Although some of these features are well known for plants of given time periods, particularly the Carboniferous, trends in character evolution have never been adequately documented for the group as a whole. A better understanding of such trends throughout the isoetalean fossil record could be valuable in distinguishing evolutionary lineages from convergence. It is interesting that several morphological characters of modern Isoetes are present as early as the Triassic: monolete microspores, sunken sporangia and elaborate ligules with glossopodia occur within elongatestemmed Triassic forms. The dominant plant habit of modern Isoetes, a reduced cormose form that lacks appreciable stem elongation, originated at least by the Jurassic and typifies late Mesozoic and Cenozoic isoetaleans.

American Journal of Botany, 2005

The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern No... more The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern North America, and one in western Asia. Mature infructescences are studied to provide anatomical, morphological, and micromorphological details, some of which are newly recognized. Homology is suggested between extrafloral spinose processes of L. formosana and L. acalycina, braid-like ornamentation of L. styraciflua, and broad intercarpellate areas of L. orientalis. Morphology, position, number, and the presence of similar structures in the closely related Hamamelidaceae s.s. support their derivation from sterile flowers. Morphological cladistic analysis using 43 characters supports the monophyly of Liquidambar with Altingia as its sister. The matK analysis contrastingly places Altingia sister to the L. acalycina-L. formosana clade, rendering Liquidambar paraphyletic. Discordance between morphological and matK data sets may result from both different rates of morphological evolution and convergence. Several similarities between Altingia and L. acalycina are symplesiomorphic in the morphological cladistic analysis. Microaltingia apocarpela, from the Cretaceous of eastern North America, documents the earliest known fossil divergence within Altingiaceae. The Miocene Liquidambar changii of western North America is sister to a clade of extant Liquidambar species. Consideration of this fossil evidence reveals complex intercontinental biogeographic disjunctions in Altingiaceae.

American Journal of Botany, 2008

American Journal of Botany, 1987

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact

American Journal of Botany, 2007

Botanical Gazette, 1986

The genus Microspermopteris is characterized as a small lyginopterid pteridosperm with a pentarch... more The genus Microspermopteris is characterized as a small lyginopterid pteridosperm with a pentarch protostele, irregular cortical ridges, and multicellular trichomes. We describe the frond architecture and vari ability among axillary branches previously unknown for the genus. Fronds are small and delicate, exhibiting three orders of branching. Clasping V-shaped petioles produce primary pinnae alternately to suboppositely from adaxial projections. Primary pinnae in turn produce secondaries that bear two-, three-, or four-lobed ultimate laminar pinnules. Pinnules reconstructed from serial sections are morphologically similar to Sphenopteris-\ike compressions; however, the overall frond is reduced in size and complexity. While some axillary branches produce secondary xylem, others are composed entirely of primary tissues. Some axillary branches produce scalelike leaves in a tight helix; distally, immature buds are surrounded by flattened bud scales. Although Microspermopteris shows similarities to Heterangium in stelar and cortical anatomy, the two taxa are distinct. Microspermopteris is interpreted as a delicate, scrambling vine, liana, or shrublike plant in contrast to the more robust lyginopterids Lvginopteris, Schopfiastrum, and Heterangium.

Review of Palaeobotany and Palynology, 1991

The Middle Eocene Princeton chert from southern British Columbia represents one of the richest kn... more The Middle Eocene Princeton chert from southern British Columbia represents one of the richest known assemblages of permineralized Tertiary plants. Affinities with modern aquatic angiosperms, anatomical modifications for the aquatic habit and associated fresh water faunal elements support the interpretation of some components of the Princeton chert as in situ aquatic plants. Among these are fossil plants with affinities to the extant Nymphaeaceae (Allenbya), Araceae (KeratospermaL Alismataceae (Heleophyton), Cyperaeeae/Juncaceae (Ethela) and Lythraceae (Decodon). Anatomical modifications include aerenchyma in vegetative tissues (Eorhiza, Dennstaedtiopsis, Heleophyton and Uhlia), the thin-walled tracheary elements without prominent secondary wall thickenings and the presence of protoxylem lacunae surrounded by a ring of cells with thickened inner walls (Heleophyton). Seeds that share morphological features with extant aquatics are characterized by a palisade layer, operculum, external mucilage, small amounts of endosperm and abundant perisperm. Associated faunal elements include turtle bones in the peat matrix and freshwater fish at the top of the section. In situ preservation of these aquatic forms is supported by the presence of rooted axes, the large number of plant organs of the same type and preservation of complete flowers, delicate tissues and organic connections allowing for whole plant reconstruction.

Journal of the Botanical Research Institute of Texas

We dedicate this volume to our friend, mentor, and colleague who gave us so generously of his tim... more We dedicate this volume to our friend, mentor, and colleague who gave us so generously of his time, encyclopedic knowledge, wisdom, good humor, and patience. Dr. Pinkava mentored 35 students as chair or co-chair, including seven Ph.D. students, many of whom have launched their own academic careers (see list of graduate students at the end). He published generously with his students on Cactaceae, the Flora of Arizona and documenting new chromosome counts for both (see bibliography below).

American Journal of Botany, Jan 1, 2004

American Journal of Botany, Jan 1, 2005

The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern No... more The sweet gum genus Liquidambar (Altingiaceae) has two species in eastern Asia, one in eastern North America, and one in western Asia. Mature infructescences are studied to provide anatomical, morphological, and micromorphological details, some of which are newly recognized. Homology is suggested between extrafloral spinose processes of L. formosana and L. acalycina, braid-like ornamentation of L. styraciflua, and broad intercarpellate areas of L. orientalis. Morphology, position, number, and the presence of similar structures in the closely related Hamamelidaceae s.s. support their derivation from sterile flowers. Morphological cladistic analysis using 43 characters supports the monophyly of Liquidambar with Altingia as its sister. The matK analysis contrastingly places Altingia sister to the L. acalycina-L. formosana clade, rendering Liquidambar paraphyletic. Discordance between morphological and matK data sets may result from both different rates of morphological evolution and convergence. Several similarities between Altingia and L. acalycina are symplesiomorphic in the morphological cladistic analysis. Microaltingia apocarpela, from the Cretaceous of eastern North America, documents the earliest known fossil divergence within Altingiaceae. The Miocene Liquidambar changii of western North America is sister to a clade of extant Liquidambar species. Consideration of this fossil evidence reveals complex intercontinental biogeographic disjunctions in Altingiaceae.