Lauraceae macrofossils and dispersed cuticle from the Miocene of southern New Zealand

Twenty-five species of Lauraceae cuticle are described from 120 fossil-bearing samples from two Early Miocene basins in southern New Zealand; the St Bathans Paleovalley of the Manuherikia Group, and the Gore Lignite Measures of the East Southland Group. The genera Endiandra and Cryptocarya are identified, which are no longer in the extant flora of New Zealand, and Beilschmiedia and Litsea which are in the extant flora. In the St Bathans Paleovalley it is likely that at least 22 species were growing as part of a single broader community. The presence of Lauraceae at this latitude in New Zealand and their high diversity clearly implies warmer temperatures than currently exist at lowland locations at that latitude today, which lie to the south of the existing limit of the family. Copyright: Paleontological Society April 2007

Gymnostoma tasmanianum sp nov., a fossil Casuarinaceae from the Early Oligocene of Little Rapid River, Tasmania, Australia

Int. J Plant Sci. 164(4):629–634. 2003. © 2003 by The University of ChicagoMacrofossils of Casuarinaceae from Early Oligocene sediments at Little Rapid River, Tasmania, are assigned to a new species, Gymnostoma tasmanianum. This is only the second species of fossil Gymnostoma to be formally described and the first species of Gymnostoma to be described from Tasmania. The species is known from both vegetative and reproductive organs. The new taxon is distinguished from other known species by its small stomata, short article length and tooth width, small length:width ratio of articles, glabrous articles, stomata in two to five rows, and teeth elongate with acute apices and sinuses. The fossil record shows that Gymnostoma once had a much wider distribution in Australia than its current occurrence in far north Queensland.Greg Guerin and Robert S. Hil

Permian ginkgophyte fossils from the Dolomites resemble extant O-ha-tsuki aberrant leaf-like fructifications of Ginkgo biloba L

<p>Abstract</p> <p>Background</p> <p>Structural elucidation and analysis of fructifications of plants is fundamental for understanding their evolution. In case of <it>Ginkgo biloba</it>, attention was drawn by Fujii in 1896 to aberrant fructifications of <it>Ginkgo biloba </it>whose seeds are attached to leaves, called <it>O-ha-tsuki </it>in Japan. This well-known phenomenon was now interpreted by Fujii as being homologous to ancestral sporophylls. The common fructification of <it>Ginkgo biloba </it>consists of 1-2 (rarely more) ovules on a dichotomously divided stalk, the ovules on top of short stalklets, with collars supporting the ovules. There is essentially no disagreement that either the whole stalk with its stalklets, collars and ovules is homologous to a sporophyll, or, alternatively, just one stalklet, collar and ovule each correspond to a sporophyll. For the transition of an ancestral sporophyll resembling extant <it>O-ha-tsuki </it>aberrant leaves into the common fructification with stalklet/collar/ovule, evolutionary reduction of the leaf lamina of such ancestral sporophylls has to be assumed. Furthermore, such ancestral sporophylls would be expected in the fossil record of ginkgophytes.</p> <p>Results</p> <p>From the Upper Permian of the Bletterbach gorge (Dolomites, South Tyrol, Italy) ginkgophyte leaves of the genus <it>Sphenobaiera </it>were discovered. Among several specimens, one shows putatively attached seeds, while other specimens, depending on their state of preservation, show seeds in positions strongly suggesting such attachment. Morphology and results of a cuticular analysis are in agreement with an affiliation of the fossil to the ginkgophytes and the cuticle of the seed is comparable to that of Triassic and Jurassic ones and to those of extant <it>Ginkgo biloba</it>. The <it>Sphenobaiera </it>leaves with putatively attached seeds closely resemble seed-bearing <it>O-ha-tsuki </it>leaves of extant <it>Ginkgo biloba</it>. This leads to the hypothesis that, at least for some groups of ginkgophytes represented by extant <it>Ginkgo biloba</it>, such sporophylls represent the ancestral state of fructifications.</p> <p>Conclusions</p> <p>Some evidence is provided for the existence of ancestral laminar ginkgophyte sporophylls. Homology of the newly found fossil ginkgophyte fructifications with the aberrant <it>O-ha-tsuki </it>fructifications of <it>Ginkgo biloba </it>is proposed. This would support the interpretation of the apical part of the common <it>Ginkgo biloba </it>fructification (stalklet/collar/ovule) as a sporophyll with reduced leaf lamina.</p

Taxonomic differences between Pinus sylvestris and P. uncinata revealed in the stomata and cuticle characters for use in the study of fossil material

Taxonomic differences in the needle epidermis characteristics of Pinus sylvestris L. and Pinus uncinata Ramond ex DC. from two Iberian populations were sought; such information could help identify these species when pollen analysis and the inspection of wood anatomy fails. The features of the cuticle are commonly well preserved in the fossil record. Although the epidermal patterns of the examined taxa were similar, qualitative differences were seen in the subsidiary and guard cells. P. sylvestris showed small subsidiary cells homogenously arranged around the opening of the epistomatal chamber, while P. uncinata showed small, lateral subsidiary cells and non-differentiated subsidiary cells in the polar position. The aperture of the epistomatic chamber of P. uncinata was also larger in diameter (15.1 ± 1.8 µm P. sylvestris; 21.1 ± 2.8 µm P. uncinata). Principal components analysis and discriminant analysis was performed on the features of the guard cells characterising the size and shape of the cuticular thickenings — all the variables analysed can be measured in disperse stomata in microscope preparations for pollen analysis. Significant differences were found in the upper woody lamellae width and the coefficient associated with the shape of the medial lamellae borders (discriminant analysis weighting 0.739 and 0.826 respectively). Other significant parameters included the coefficient associated with the relative size of the medial lamellae border width of the guard cells with respect to the distance between the external limits of the medial lamellae borders, and the length of the upper woody lamella. Different light regimens appeared not to significantly affect the variability of the studied features

Eobowenia gen. nov. from the early Cretaceous of Patagonia: indication for an early divergence of Bowenia?

Background: Even if they are considered the quintessential "living fossils", the fossil record of the extant genera of the Cycadales is quite poor, and only extends as far back as the Cenozoic. This lack of data represents a huge hindrance for the reconstruction of the recent history of this important group. Among extant genera, Bowenia (or cuticles resembling those of extant Bowenia) has been recorded in sediments from the Late Cretaceous and the Eocene of Australia, but its phylogenetic placement and the inference from molecular dating still imply a long ghost lineage for this genus.Results: We re-examine the fossil foliage Almargemia incrassata from the Lower Cretaceous Anfiteatro de Ticó Formation in Patagonia, Argentina, in the light of a comparative cuticular analysis of extant Zamiaceae. We identify important differences with the other member of the genus, viz. A. dentata, and bring to light some interesting characters shared exclusively between A. incrassata and extant Bowenia. We interpret our results to necessitate the erection of the new genus Eobowenia to accommodate the fossil leaf earlier assigned as Almargemia incrassata. We then perfom phylogenetic analyses, including the first combined morphological and molecular analysis of the Cycadales, that indicate that the newly erected genus could be related to extant Bowenia.Conclusion: Eobowenia incrassata could represent an important clue for the understanding of evolution and biogeography of the extant genus Bowenia, as the presence of Eobowenia in Patagonia is yet another piece of the biogeographic puzzle that links southern South America with Australasia

Speedy grass stomata: emerging molecular and evolutionary features

No abstract available

A new species of Solanum L.(Solanaceae) from Baghdad city Iraq

Solanum americanum is a new annual shrubby plant seen recently in fields and gardens of Baghdad city. A new species is described and illustrated, inhabit wet or semi dry places and have consequently a mesophytic habit. A detailed morphological study of the stems, leaves, Inflorescence, flower, male and female reproductive organs and fruits has been done, revealed several interesting taxonomic characteristics, which have not previously been studied in Iraq. Also, anatomical studies reveals constant taxonomical characteristics such as the presence of anthocayanine in outer row of epidermis, distinct chlorenchyma in whole cortex, the wide pith of stems, and presence of distinct mesophyll that differentiated into palisade layer and spongy layer in leaves, amphistomatic bearing anomocytic stomatal complexes that are significant and constant characteristics in species studied

Leaf Micromorphology Aids Taxonomic Delineation within the Hypervariable Genus Metrosideros (Myrtaceae) on O\u27ahu

Variation in leaf micromorphology can aid delimitation of taxonomically difficult groups. The woody genus Metrosideros (Myrtaceae) dominates Hawai\u27i\u27s native forests and comprises striking, predominantly infraspecific, macromorphological variation, including many forms unrecognized in current taxonomic treatments. On taxonomically rich O\u27ahu, 10 taxa (varieties or unnamed morphotypes of M. polymorpha and other species) occur in a predictable sequence with overlapping ranges from low to high elevation along the numerous leeward ridges of the Ko\u27olau Range. We used scanning electron and light microscopy to examine mature, nonsenescing sun leaves from each of these 10 taxa. Parametric and nonparametric tests were used to compare stomatal complex (SC) traits and those of a newly described secretory structure (SS) across taxa. Correlations among traits and discriminant analyses were also done. Density and length of SCs were inversely related overall, and both measures varied significantly across taxa. Although abaxial SSs were consistently present only in the two highest-elevation glabrous taxa, adaxial SSs were present in all 10 taxa. Length and density of adaxial SSs and density of abaxial SSs varied across taxa, and densities of both SCs and SSs were greatest at high elevation. Combined, the SC and SS traits differentiated 100% of four glabrous varieties and two of three pubescent varieties of M. polymorpha. Variation in leaf micromorphology, including presence and density of a newly described SS, aids delimitation of closely related Hawaiian Metrosideros taxa and may refilect differential local adaptation across a heterogeneous landscape

A putative approach for influencing stomatal density by over-expressing NADP-dependent malic enzyme in arabidopsis

Stomata are leaf structures critical for plant survival because they modulate the rate of transpiration. This study will examine a possible mode for regulating stomatal density by over-expressing NADP-dependent malic enzyme (NADP-ME), which is thought to deplete the counter-anion pool in Arabidopsis thaliana guard cells. It was hypothesized that over-expressing NADP-ME in Arabidopsis will elevate stomatal density. Scanning electron microscopy was employed to determine if any differences exist in numbers of stomatal complexes among transgenic lines and wild-type Arabidopsis. The results indicated a significant increase in stomatal numbers among some transgenic plant lines relative to the wild-type. Second, a series of molecular tests were utilized to provide NADP-ME activity and transgene expression evidence. These included western blots, tissue assay blots, enzyme activity assays, and RT-PCR reactions. Altering NADP-ME expression levels may present a putative approach for influencing stomatal development

Fluctuating auxin response gradients determine pavement cell-shape acquisition

Puzzle-shaped pavement cells provide a powerful model system to investigate the cellular and subcellular processes underlying complex cell-shape determination in plants. To better understand pavement cell-shape acquisition and the role of auxin in this process, we focused on the spirals of young stomatal lineage ground cells of Arabidopsis leaf epidermis. The predictability of lobe formation in these cells allowed us to demonstrate that the auxin response gradient forms within the cells of the spiral and fluctuates based on the particular stage of lobe development. We revealed that specific localization of auxin transporters at the different membranes of these young cells changes during the course of lobe formation, suggesting that these fluctuating auxin response gradients are orchestrated via auxin transport to control lobe formation and determine pavement cell shape