Premise of research. A large number of floating aquatic aroid fossils have been recovered from pond sediments in the Hell Creek Formation (Upper Cretaceous) of South Dakota, providing valuable new data about aquatic vegetation of the uppermost Cretaceous, that are used to describe a new species of the genus Cobbania, and to evaluate associated reproductive structures and phylogenetic relationships among floating aquatic monocots.
Methodology. Fossils were uncovered as needed with fine needles to reveal surface features of the specimens. Images were captured with a digital scanning camera, and phylogenetic analyses were conducted with TNT implemented through WinClada.
Pivotal results. The new species, Cobbania hickeyi Stockey, Rothwell & Johnson, extends the range of the genus to the uppermost Cretaceous, supports the taxonomic integrity of the genus Cobbania, and increases our understanding of structural variation and species richness within the genus. Associated reproductive structures include an aroid spadix, strengthening the assignment of Cobbania to the Araceae. Phylogenetic analyses using “total-evidence” data help resolve conflicting results from either morphological or nucleotide sequence analyses of relationships among floating aquatic aroids, and the fossil taxon Aquaephyllum does not nest among the other floating aquatic species in any of our results.
Conclusions. Species of the genus Cobbania were an important component of aquatic vegetation across the Northern Hemisphere during the Late Cretaceous. In tests of competing hypotheses for relationships among Pistia stratiotes, Cobbania spp., and species of Araceae subfamily Lemnoideae, the results from a “total-evidence” analysis suggest that specializations for the floating aquatic life form may be overwhelming other characters in the results of morphological analyses alone.
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... Fossil Araceae recently have received increased scrutiny, because the pattern of structural evolution, the order of appearance of subfamilies, and extinct plants with well-documented ages are critical to our understanding of monocot evolution and biogeography. The characterization of new aroid leaf morphotypes (e.g., Wilde et al. 2005;Bogner et al. 2007; Kvaček and Smith 2015;Stockey et al. 2021), and increasing numbers of spadices from the Cretaceous Stockey 2006;Krassilov and Kodrul 2009;Stockey et al. 2016;Sender et al. 2019) and Paleogene (Crepet 1978;Stockey et al. 2021), has helped to de-ne patterns of aroid morphological evolution and phylogeny through time (Stockey et al. 1997(Stockey et al. , 2007(Stockey et al. , 2021Rothwell et al. 2004;Krassilov and Kodrul 2009;Sender et al. 2019). However, many more investigations of the fossil record will be required to rmly establish those patterns. ...
... Fossil Araceae recently have received increased scrutiny, because the pattern of structural evolution, the order of appearance of subfamilies, and extinct plants with well-documented ages are critical to our understanding of monocot evolution and biogeography. The characterization of new aroid leaf morphotypes (e.g., Wilde et al. 2005;Bogner et al. 2007; Kvaček and Smith 2015;Stockey et al. 2021), and increasing numbers of spadices from the Cretaceous Stockey 2006;Krassilov and Kodrul 2009;Stockey et al. 2016;Sender et al. 2019) and Paleogene (Crepet 1978;Stockey et al. 2021), has helped to de-ne patterns of aroid morphological evolution and phylogeny through time (Stockey et al. 1997(Stockey et al. , 2007(Stockey et al. , 2021Rothwell et al. 2004;Krassilov and Kodrul 2009;Sender et al. 2019). However, many more investigations of the fossil record will be required to rmly establish those patterns. ...
... A small stipitate spadix associated with the oating aquatic aroid, Cobbania hickeyi Stockey, Rothwell & Johnson (2016) has been described from the Late Cretaceous Hell Creek Formation of North Dakota. Like other compression specimens, this fossil spadix is difcult to compare to Appianospadix for want of anatomical detail. ...
... Although in situ aquatic plants are relatively uncommon in Cretaceous-Paleogene deposits, wetland assemblages have been identified with increasing frequency over the past several years (e.g., Upchurch et al., 1994;Stockey et al., , 2007Stockey et al., , 2016Kva cek, 1998Kva cek, , 2003Riley andStockey, 2000, 2004;Riley, 2003;Kva cek et al., 2004;Wilde et al., 2005;Quan and Sun, 2008;Bogner and Kva cek, 2009;Krassilov and Kodrul, 2009;Cuneo et al., 2014;Liang et al., 2021;Pott et al., 2021;Edmonds et al., 2022;Vera et al., 2022). These assemblages reveal that well-established wetland plant communities, generally similar to modern vegetation (e.g., Cook, 1996), were common throughout the Northern Hemisphere before the end of the Mesozoic (e.g., Hoffman, 2019;Pott et al., 2021). ...
... Other specimens show both fine venation in some areas (Fig. 3E) and the polygonal pattern in others (Fig. 3E, at arrow). From the size range and even distribution of the polygonal pattern ( Fig 3F), we interpret this to be sub-epidermal aerenchyma like that of other aquatics (e.g., Cobbania spp.; Stockey et al., 2016), with individual areas separated by what appear to be uni-or biseriate chains of mesophyll cells. By comparison to the leaves of living aquatics the aerenchyma of Z. crenulata is positioned to the abaxial side of the venation (Kaul, 1976). ...
... As compared to fossils from mesic habitats (e.g., Wing et al., 2012), a relatively smaller number of wetland angiosperms have been described from Cretaceous and Paleogene deposits. Most are monocots that bear simple leaves in a helical phyllotaxis, and are assignable to the families Araceae and Lemnaceae (Golovneva, 1994(Golovneva, , 2000Kva cek, 1995;Stockey et al., , 2007Stockey et al., , 2016Pott et al., 2021). However, eudicots, including those with both simple and compound leaves also are present in the Late Cretaceous assemblages (e.g., Golovneva, 1991;McIver and Basinger, 1993;. ...
Sixty-seven coalified compression specimens of leaves, one attached to a stem, have been found in the St. Mary River Formation (uppermost Campanian–lowermost Maastrichtian, Upper Cretaceous) near Cardston, Alberta, Canada. Leaves have long multi-veined petioles with clasping bases, and an ellipsoid to obovate lamina with a convex to almost flat apex, and a crenate margin with one order of convex-convex chloranthoid teeth with angular sinuses. Tooth apices often end in a small concavity interpreted as a hydathode. Several primary veins enter the lamina in a flabellate manner. The central primary vein branches pinnately while lateral primaries, dichotomize toward the margin producing a reticulodromous pattern of secondaries. Secondaries arising from the lateral primary veins are the result of consistent dichotomies and anastomoses with a concurrent loss of gauge. Tertiary veins are alternate percurrent, and quaternaries form an irregular reticulate fabric. Quinternary veins form polygonal areoles with freely ending veinlets. Some specimens show a polygonal pattern of sub-epidermal aerenchyma like that of many other aquatics. Plants are compared to other fossil aquatic taxa, including those from the St. Mary River Formation and extant members of Ranunculaceae, Menyanthaceae and Nymphaeaceae. The specimens are described as a new amphibious aquatic: Zlatkovia crenulata Rothwell & Stockey gen. et sp. nov., eudicot family incertae sedis. This assemblage meaningfully enriches our understanding of aquatic and adjacent wetland habitats near the close of the Cretaceous, and emphasizes that the structure of modern wetland communities was well established before the end of the Mesozoic.
... In this article we describe floating aquatic rosettes of a new plant from the St. Mary River Formation that, like Q. angulata, has both simple and compound leaves attached in rosettes with determinate growth. We distinguish these from Quereuxia and other fossil forms (e.g., Cobbania corrugata Stockey, Rothwell & Johnson 2007, Cobbania hickeyi Stockey, Rothwell & Johnson 2016, F. marsilioides (Bell) McIver & Basinger [1993], and Limnobiophyllum scutatum Krassilov emend. Kvaček 1995;, as well as from extant angiosperms that produce aquatic floating rosettes, including the eudicots Trapa natans L. (Lythraceae), Ludwigia sedioides (Humb. ...
... The North American monocot genus Cobbania Stockey, Rothwell & Johnson (2007) now includes at least two species-Cobbania corrugata (Lesquereux) Stockey, Rothwell & Johnson (2007) and Cobbania hickeyi Stockey, Rothwell & Johnson (2016)-and it also has been reported from several other localities, including some in Russia and China (Bogner 2009;Krassilov and Kodrul 2009). The floating aquatic rosettes of Cobbania spp. ...
... The North American monocot genus Cobbania Stockey, Rothwell & Johnson (2007) now includes at least two species-Cobbania corrugata (Lesquereux) Stockey, Rothwell & Johnson (2007) and Cobbania hickeyi Stockey, Rothwell & Johnson (2016)-and it also has been reported from several other localities, including some in Russia and China (Bogner 2009;Krassilov and Kodrul 2009). The floating aquatic rosettes of Cobbania spp. ...
... Fossil Araceae have been receiving increased scrutiny in response to the growing realization that extinct plants with well-documented ages are critical to the understanding of monocot evolution and biogeography. Recent efforts have led to the characterization of new aroid leaf morphotypes (e.g., Wilde et al., 2005;Bogner et al., 2007;Kvaček and Smith, 2015) and to the description of increasing numbers of spadices from the Cretaceous Krassilov and Kodrul, 2009;Stockey et al., 2016;Sender et al., 2019) and Paleogene (Crepet, 1978;Stockey and Gemmell, 2008). These studies are helping to define patterns of aroid morphological evolution and phylogeny through time (Stockey et al., 1997(Stockey et al., , 2007(Stockey et al., , 2017Rothwell et al., 2004;Krassilov and Kodrul, 2009;Sender et al., 2019), but much more dense sampling of the fossil record will be required to firmly establish those patterns. ...
... At the time of that interpretation, the position of Acorus in monocot phylogeny was not known, and this fossil needs to be reexamined in light of recent phylogenetic studies in Alismatales. Stockey et al. (2016) described a stipitate spadix associated with the whole plants of Cobbania hickeyi Stockey, Rothwell & K.R. Johnson, a floating aquatic aroid from the Late Cretaceous (late Maastrichtian) Hell Creek Formation of North Dakota (Appendix S1, Table S2). This spadix has at least 60 helically arranged coalified structures that might be flowers on the exposed surface. ...
... mm in diameter, and show a dark central spot that could be the stigma. The uniform structure of the hexagonal compressions suggests that this spadix produced flowers of only one morphology, characteristic of aroid spadices with bisexual flowers, but no tepals could be distinguished on this specimen (Stockey et al., 2016). The spadix axis is 6 mm wide and at least 12 mm long, borne on a larger axis at least 33 mm long and 9 mm wide, which might also include the base of a broken spathe. ...
Premise:
Nearly 200 araceous leaves and two spadices have been identified among Paleocene fossils from the Blindman River locality near Blackfalds, Alberta, Canada. Although not found in attachment, these probably represent parts of the same extinct plant species.
Methods:
Specimens were studied using light microscopy. Phylogenetic analyses using a morphological matrix of living and fossil Araceae were performed using TNT version 1.5 to help establish relationships of the fossil leaves and spadices within Araceae and to each other.
Results:
Leaves are simple with a broad petiole, entire margin, and elliptic to ovate or oblong blade with an acute to slightly rounded apex. A multi-veined midrib extends into the basal region of the blade. Parallelodromous primary veins of two orders diverge at acute angles, converging with a submarginal vein or at the apex. Transverse veins are opposite percurrent, producing rectangular to polygonal areoles. Higher-order veins are mixed opposite/alternate. Spadices are cylindrical, with helically arranged, bisexual, perigoniate flowers, each with six free tepals and a protruding style. Fruits are trilocular, with axile placentation and one seed per locule.
Conclusions:
Leaves are assignable to the fossil genus Orontiophyllum J. Kvaček & S.Y. Sm. as O. grandifolium comb. nov. Spadices are described as Bognerospadix speirsiae gen. et sp. nov. Leaves and spadices each conform to an early-diverging lineage of Araceae, increasing the known diversity of Proto-Araceae (viz., subfamilies Gymnostachydoideae and Orontioideae). Together, they provide strong evidence for extinct Proto-Araceae with novel combinations of characters shortly after the Cretaceous-Paleogene floral transition.
... The fossil record of Araceae has increased in the last two decades, which has been important to enhance the knowledge of the evolution and their phylogenetic relationships (e.g. Stockey et al. , 2007Stockey et al. , 2016Bogner et al. 2005Bogner et al. , 2007Nauheimer et al. 2012;Gallego et al. 2014;Coiffard and Mohr 2016). During the Cretaceous, this family was geographically widespread (Stockey et al. , 2007(Stockey et al. , 2016Friis et al. 2004Friis et al. , 2010Bogner et al. 2007;Herrera et al. 2008;Gallego et al. 2014). ...
... Stockey et al. , 2007Stockey et al. , 2016Bogner et al. 2005Bogner et al. , 2007Nauheimer et al. 2012;Gallego et al. 2014;Coiffard and Mohr 2016). During the Cretaceous, this family was geographically widespread (Stockey et al. , 2007(Stockey et al. , 2016Friis et al. 2004Friis et al. , 2010Bogner et al. 2007;Herrera et al. 2008;Gallego et al. 2014). The earliest fossils of Araceae have been recorded since late Aptian-early Albian of the Figueira da Foz Formation, Portugal (Friis et al. 2004(Friis et al. , 2010, late Aptian in the Crato Formation, Brazil (Coiffard et al. 2013) and late Albian, Spain (Sender et al. 2018). ...
... In the Late Cretaceous, floating aquatic plants, including mono and dicotyledonous, were widespread and diverse Stockey et al. , 2007Stockey et al. , 2016Martin-Closas 2003;Bogner et al. 2005Bogner et al. , 2007Quan and Sun 2008;Gallego et al. 2014). The fossil record indicates that Laurasia was the region where the Araceae probably originated (late Aptian to early Albian, Portugal) (Friis et al. 2010); however, they were also found in western Gondwana at the same time (late Aptian, Brazil) (Nauheimer et al. 2012). ...
In this work, a new genus and species, Natantisphyllum crenae from the Late Cretaceous, central-western Argentina, assigned to the family Araceae was described based on fossil vegetative remains. The morphology of the leaves, especially the venation pattern of several vein orders, were compared with leaves of fossil and extant floating aquatic aroids. We performed a phylogenetic analysis to test the position of the new fossil in a phylogenetic tree and its relationship with other living and fossil representatives of Araceae. Natantisphyllum crenae possesses an unique combination of characters, then it cannot be placed within any other fossil or extant recognised aroid taxa and constitutes the southernmost record of a floating aquatic aroid. The phylogenetic relationships of the new fossil with other members of Araceae suggest that N. crenae is closely related to the fossil Aquaephyllum auriculatum. Both fossils from South America appear related to the modern aquatic Pistia and Lemnoideae and the fossil taxa from North America (Lymnobiophyllum and Cobbania) sharing a common ancestor.
... For example, Taylor et al. (2008) showed that members of the Cabombaceae were present as aquatic plants in the Cretaceous, and Friis et al. (2010, page 373) stated that "Nymphaeales were clearly present at an early stage in angiosperm evolution." The fossil record shows that, not only basal angiosperms, but also plants at the base of the eudicot line (Taylor et al. 2008;Friis et al. 2010Friis et al. , 2018, basal core eudicots Bacon et al. 2018), and monocots, although having a sparse early fossil history (Stockey 2006;Stockey et al. 2016; see also Boyce and Leslie, 2012;Magallón et al., 2015), were present early in angiosperm evolution. Gomez et al. (2015) showed that the aquatic fossil Montsechia was closely related to Ceratophyllum, sister to the eudicots, as opposed to monocots (see questions raised by Soltis et al., 2018, and others). ...
... It would be rewarding to have anatomically preserved stems of Archefructus and fossil water lilies. More anatomical details are also needed about early fossils of the monocots and the Acoraceae, specifically (see Stockey 2006;Stockey et al., 2016), in order to find stem specimens that might reveal anatomical details. After all, the Nymphaeales have been present for a very long time as early Cretaceous fossils with Archefructus as the prime example (Sun et al., 1998(Sun et al., , 2002Wang and Dilcher 2006;Taylor et al. 2008;Friis et al., 2010). ...
A sampling of angiosperms across a broad spectrum of families and generas was done to determine if angiosperms from the ANA grade basal angiosperms to the Zingiberales of the monocots and Apiales of the eudicots had an endodermis with demonstrable Casparian bands in shoots because the literature has a paucity of demonstrable images, especially for key basal plants. In the Amborellales, Amborella had no stem endodermis, but the aquatic Trithuria of the Nymphaeales had a monostele in which a layer endodermis enclosed its stem axial vascular tissues. Cabomba, Brasenia, and Nuphar of the Nymphaeales had polysteles in which an endodermis of distinct Casparian bands encircled each axial vascular bundle; Nymphaea had either an atactostele or a reduced polystele with only a few axial vascular bundles surrounded by endodermis. Among the magnoliids, Saururus and Houttuynia had monosteles with distinct endodermis Casparian bands. In many monocots, from Acorus, Acorales, to Thalia, Zingiberales, there was a monostele with an endodermis of Casparian bands surrounding a central cylinder of scattered axial vascular bundles. At the base of the eudicots, Ceratophyllum had a vascular core without endodermis. Some members of the Ranunuculales had stem endodermis in a polystelic arrangement. Nelumbo, Proteales, had a monostele of Casparian bands only in stolons. Unusual endodermal and vascular patterns, siphonosteles, were found in Gunnera, Gunnerales. Most eudicots with stem endodermis usually had a monostele or one endodermal layer of Casparian bands only surrounding one ring of vascular bundles, e. g., Myriophyllum, Drosera, Hippuris, Alternanthera, Lysimachia, and Hydrocotyle, but a polystele was present in Justicia. Some leaf petioles and lamina, e. g., Gunnera, Myriophyllum, Hippuris, and Hydrocotyle, had endodermis around their individual vascular bundles. While a stem endodermis was a distinct feature of aquatic or wetland plants, derived from terrestrial ancestors, the presence of stem endodermis by plants at the bases of some major angiosperm lines suggests that it may have been present early in angiosperm evolution.
... Because of their extreme morphological reduction, duckweeds traditionally were difficult to place among other angiosperms. Fossils of apparent duckweed relatives have supported a link with the large family Araceae (Kvaček 1995;Stockey et al. 1997Stockey et al. , 2007Stockey et al. , 2016Coiffard and Mohr 2018), and various morphological data also support the current understanding of Lemnaceae as closely related to Araceae (summarized by Les et al. 2002). Ongoing molecular phylogenetic studies (Cabrera et al. 2008;Cusimano et al. 2011;Henriquez et al. 2014) have begun to portray a consistent phylogenetic position for Lemnaceae, albeit based solely on plastid DNA data. ...
... They reconstructed the common ancestor of all Araceae to be North American, whereas the sibling lineage of duckweeds was reconstructed to have a Eurasian ancestor. Fossil duckweed relatives recovered from late Cretaceous formations in North America (Kvaček 1995;Stockey et al. 1997Stockey et al. , 2007Stockey et al. , 2016 may represent extinct lineages that predated the clade of extant duckweeds, and it is noteworthy that contemporary fossils putatively related to duckweeds also have been recovered from Africa (Coiffard and Mohr 2018). ...
Duckweeds (family Lemnaceae) comprise 37 angiosperm species, which are distributed among five genera. Although these tiny specimens represent the smallest flowering plants on earth, the group is practically ubiquitous in water bodies worldwide. The paucity of morphological features in duckweeds has made it difficult to elucidate their evolutionary history, or to present a compelling classification of the group, but more recent molecular evidence has facilitated an improved systematic evaluation of these unique plants. The duckweeds are closely related to aroids (family Araceae), with which they share several morphological features. Within Lemnaceae, the two species of Spirodela and the monotypic genus Landoltia are more distantly related to other duckweeds than are the larger genera Lemna, Wolffia, and Wolffiella to one another. A substantial amount of plastid DNA sequence data has upheld a phylogeny for the family that is mostly consistent, and many of those relationships have been corroborated by the recent addition of nuclear DNA data. Morphologically, the genera lacking roots (Wolffia and Wolffiella) comprise a single lineage, as do the three largest genera (Lemna, Wolffia, and Wolffiella) that are more reduced in comparison with Landoltia and Spirodela. The biogeography of Lemnaceae indicates that numerous dispersal events have occurred in relatively recent evolutionary time, and that several species essentially are cosmopolitan. Although not particularly speciose, duckweeds comprise a surprisingly diverse group with much potential for exploring various genetic, biochemical, and metabolic phenomena.
... Reproductive structures with cluster of seeds and dispersed seeds associated with these leaf rosettes are assigned to Cobbanicarpites amurensis Krassilov et Kodrul. Cobbania corrugata is now considered as belonging to the family Araceae (Stockey et al., 2007(Stockey et al., , 2016. Quereuxia angulata is represented by floating rosettes and dissected submerged leaves, attached to stems. ...
A general characterization of the Late Cretaceous floras of the Zeya-Bureya Basin is provided based on floristic assemblages from Russia (Amur Region) and China (Heilongjiang Province). Four phases of floral evolution were revealed: the Turo-nian-Coniacian (the Sutara flora), the Santonian (the Yong'ancun and Middle Kundur floras), the Campa-nian (the Taipinglinchang and Late Kundur floras) and the late Maastrichtian (Bureya flora). This long paleofloral succession provides possibility for investigation of different trends in the evolution of the Late Cretaceous taxa, flora, and climate.
The lower Campanian members 2 and 3 of the Nenjiang Formation host a diverse array of cupressoid conifers (Glyptostrobus, Sequoiadendron, Cupressinocladus, Mesocyparis; commonly shoots and a few cones), a few unassigned conifers and putative ginkgophytes. True aquatics (Cobbania, Quereuxia) and water-bound plants (Nelumbites and Sparganiophyllum) have been recorded, as well as foliage and putative flowers of the deciduous angiosperm tree Trochodendroides. The floral composition is very similar to assemblages from the adjacent Zeya-Bureya Basin (Far East Russia), and it contains elements of contemporaneous floras from further away regions (Sakhalin, Honshu, Chukotka, Kamchatka), indicating an affiliation of the Nenjiang Flora to the Santonian–Campanian floras of north-east Asia, and corroborating a Campanian age for the examined strata of the Nenjiang Formation. Ecological assessments indicate a flora that thrived in and along the shores of a comparatively large lake that supported populations of three to four different species of free- or partly floating aquatics.
The free-floating aquatic duckweeds consist of the five genera, Spirodela, Landoltia, Lemna, Wolffiella and Wolffia, comprising 36 species within the monocot order of Alismatales. They are strongly adaptable to various environments and are widely distributed in a variety of climates all over the world except that Wolffiella species are restricted to the Americas and Africa. Among them, Spirodela species have large a flattened frond with 5-11 rhizoids while the rootless Wolffia species form an oval-shaped frond and are the smallest flowering plants. Duckweeds seldom flower and their rapid asexual propagation allows them to accumulate biomass quickly. They usually bud new generations (daughter fronds) from their reproductive pouches at the base of the mother fronds and the frond number almost doubles within 24 hunder good growth conditions yielding the fastest-growing flowering plants. They tend to be associated with nutrient-rich or eutrophic freshwater environments with slow-moving flow such as ponds, lakes, ditches, and paddy fields. While duckweeds become more reduced from Spirodela to Wolffia, their genome size varies 13-fold, ranging from 150 Mb in Spirodela polyrhiza to 1881 Mb in Wolffia arrhiza. With the development of long-read sequencing technology, the genomes of common duckweed species including S. polyrhiza, Lemna minor, Lemna gibba and Wolffia australiana have been sequenced and assembled. The underlying molecular mechanisms and regulatory networks in duckweeds under different treatments such as starvation, salt stress, heavy metal and radiation have also been revealed by transcriptome, proteome and metabolome analyses for the genera Spirodela, Landoltia, and Lemna enhancing their potential applications in the fields of phytoremediation and bioenergy. Furthermore, genetic transformation systems for some common duckweeds such as L. minor, Lemna aequinoctialis, S. polyrhiza and Wolffia globosa have been established, and especially the frond transformation systems have significantly improved transformation efficiencies (more than 90%). These characteristics have made duckweeds model systems for several decades for the study of plant physiology, biochemistry, ecotoxicology, and have contributed to knowledge of auxin biosynthesis, plant flowering and the circadian system. Duckweeds have also been widely used for the treatment of agricultural, municipal, and even industrial wastewater because they can uptake nitrogen and phosphorus as well as quickly accumulate heavy metals and organic pollutants. Besides, their accumulated biomass is rich in starch and protein and therefore can be used for feed applications and biofuels. In this review, we introduce the origin, classification and evolution of duckweeds, as well as research in morphology and anatomy, physiology, genetic transformation and omics studies. We further discuss the application of duckweeds in food, feed, bioenergy, and bioremediation. Finally, we highlight the challenges and future directions of duckweed research, providing a reference for basic biological research and resource utilization.
Some of the most conspicuous fruit and seed remains from the Middle Eocene Princeton chert locality (Allenby Formation) are assignable to the Araceae. Several thousand campylotropous, reniform, spiny seeds 2.5–3.2 mm long x 1.8–2.3 mm wide have been found dispersed in the chert. Two fruits, each with a single locule and at least eight ovules, show three distinct wall layers and appear to have been fleshy. The two layers of seed integument have pitted isodiametric sclereids aligned in radial rows, the outermost being thinner walled. Spines are borne in three rows on the dorsal seed surface while the ventral side is flattened. Idioblasts that probably contained raphides are present in the outer integument. Nucellar tissue is attached to the integument for most of its length and is well-preserved in some seeds near the chalaza and in the large conical shaped area beneath the micropyle. Endosperm cells with dark contents and curved, linear, monocotyledonous embryos are present in some seeds. Sections of seeds of living araceous taxa of the subfamilies Monsteroideae (Epipremnum, Rhodospatha) and Lasioideae (Urospatha, Cyrtosperma) were made for comparison. The fossil seeds represent a new taxon most closely related to Cyrtosperma, Keratosperma allenbyensis Cevallos-Ferriz et Stockey gen. et sp. nov., Family: Araceae, Subfamily: Lasioideae, Tribe: Lasieae. The Princeton remains are the oldest described seeds of this tribe known to date and add to our knowledge of the subtropical elements of the Princeton flora.
Various stages of ecosystem development within the Early Miocene Most Formation, the coal-bearing fill of the Most Basin in northern Bohemia, are reviewed on the basis of recent sedimentological and palaeontological studies. Several types of environment with specific plant and animal assemblages have been recognized and evaluated -low moor coal-forming mire with low nutrient supply and the ground water level near or reaching the earth surface rarely reaching a raised bog regime, shallow ox-bow lakes with various water quality, mineral back swamp along streams and in deltas on clayey and silty fat soils with an irregular supply of nutrients and a high groundwater level, flooded delta plains, riverbanks and levees with light, well aerated sand- and clay-dominated substrate well supplied by nutrients and moisture, drier habitats beyond the influence of flooding, and a deeper lake surrounded by a drier sloping upland with acid soils. Fossil records of plants, insects and lower vertebrates have been treated in more detail with special reference to palaeoenvironmental properties. Characteristics of the following newly established taxa are included - Pisces: Umbra longidorsalis Böhme, sp. nov., Plantae: Biliniasporites multilamellatus Konzalová, gen. et sp. nov., Nyssa bilinica (Unger) Z. Kvaček, comb. nov., Nyssa bilinica forma haidingeri Z. Kvaček, f. nov., Pseudotrapa buzekii Z. Kvaček, gen. et sp. nov. and Smilacinites ungeri Z. Kvaček, gen. et sp. nov.
Limnobium spongia produces upright vegetative axes and prostrate stolons. The upright axes bear new stolons, whereas the stolons bear new upright axes and fertile and sterile branching systems. Upright axes and fertile and sterile branching systems are all interpreted to have sympodial growth. However, it was not determined whether growth of stolons is monopodial or sympodial. Both stolons and upright axes branch in alternate plastochrons, and branching is achieved solely by the bifurcation of apical meristems. Each meristematic bifurcation is interpreted to represent the formation of a precocious lateral bud. The upright axes develop from presumed precocious lateral buds on stolons, whereas such buds on upright axes produce renewal shoots. Limnobium spongia exhibits a marked degree of mirror-image symmetry.
The new edition of Seeds contains new information on many topics discussed in the first edition, such as fruit/seed heteromorphism, breaking of physical dormancy and effects of inbreeding depression on germination. New topics have been added to each chapter, including dichotomous keys to types of seeds and kinds of dormancy; a hierarchical dormancy classification system; role of seed banks in restoration of plant communities; and seed germination in relation to parental effects, pollen competition, local adaption, climate change and karrikinolide in smoke from burning plants. The database for the world biogeography of seed dormancy has been expanded from 3,580 to about 13,600 species. New insights are presented on seed dormancy and germination ecology of species with specialized life cycles or habitat requirements such as orchids, parasitic, aquatics and halophytes. Information from various fields of science has been combined with seed dormancy data to increase our understanding of the evolutionary/phylogenetic origins and relationships of the various kinds of seed dormancy (and nondormancy) and the conditions under which each may have evolved. This comprehensive synthesis of information on the ecology, biogeography and evolution of seeds provides a thorough overview of whole-seed biology that will facilitate and help focus research efforts.
Tracing the evolution of one of the most ancient major branches of flowering plants, this is a wide-ranging survey of state-of-the-art research on the early clades of the monocot phylogenetic tree. It explores a series of broad but linked themes, providing for the first time a detailed and coherent view of the taxa of the early monocot lineages, how they diversified and their importance in monocots as a whole. Featuring contributions from leaders in the field, the chapters trace the evolution of the monocots from largely aquatic ancestors. Topics covered include the rapidly advancing field of monocot fossils, aquatic adaptations in pollen and anther structure and pollination strategies and floral developmental morphology. The book also presents a new plastid sequence analysis of early monocots and a review of monocot phylogeny as a whole, placing in an evolutionary context a plant group of major ecological, economic and horticultural importance.
Past phylogenetic studies of the monocot order Alismatales left several higher-order relationships unresolved. We addressed these uncertainties using a nearly complete genus-level sampling of whole plastid genomes (gene sets representing 83 protein-coding and ribosomal genes) from members of the core alismatid families, Tofieldiaceae and additional taxa (Araceae and other angiosperms). Parsimony and likelihood analyses inferred generally highly congruent phylogenetic relationships within the order, and several alternative likelihood partitioning schemes had little impact on patterns of clade support. All families with multiple genera were resolved as monophyletic, and we inferred strong bootstrap support for most inter- and intrafamilial relationships. The precise placement of Tofieldiaceae in the order was not well supported. Although most analyses inferred Tofieldiaceae to be the sister-group of the rest of the order, one likelihood analysis indicated a contrasting Araceae-sister arrangement. Acorus (Acorales) was not supported as a member of the order. We also investigated the molecular evolution of plastid NADH dehydrogenase, a large enzymatic complex that may play a role in photooxidative stress responses. Ancestral-state reconstructions support four convergent losses of a functional NADH dehydrogenase complex in Alismatales, including a single loss in Tofieldiaceae.
The nine extant genera within the Nymphaeaceae s l (Water Lilies) are shown to be separable from one another on the basis of seed morphology In particular, epidermal detail, vertical section of the testa and relative position of the micropyle and hilum are diagnostic for each genus These features are considered in connection with current systematic treatments of this family Fossil seeds are reviewed at the generic level and many of the seeds previously assigned to Brasenia ovula (Brong ) Reid and Chandler are shown to belong to an extinct genus of Nymphaeaceae intermediate between the currently accepted families Cabombacaceae and Nymphaeaceae s s They are redescribed as Sabrenia chandlerae gen et sp nov. The British Tertiary fossils Brasenia spinosa Chandler, Palaeonymphaea eocenica Chandler emend and ?Nymphaea liminis sp nov are described Fossil material of Carpolithes ovulum Brongniart 1822a, Brasenia victoria (Casp ) Weberbauer 1893, B teumeri Kirchheimer 1935, B tenuicostata Nikitin 1965 and Nymphaea arethusae Grambast 1962 has been studied for comparative purposes The use of '?' before the extant generic name is advocated when all features of a fossil indicate that it may be placed in a living genus but when certain additional, critical features of the living genus are lacking on the fossil.
