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The relict tree species Zelkova abelicea and Z. sicula (Ulmaceae) occur in Crete and Sicily, respectively. Zelkova abelicea grows in approximately 40 localities in the mountains of Crete, while Z. sicula has been found in only two stands in Sicily. We compared 25 morphological characters of the leaves of both species and used statistical methods (Tukey’stest, discrimination analysis, principal component analysis, agglomeration) to reveal the differences between these two species, their relation to Z. carpinifolia (the third Zelkova south-west Eurasian species), and between the leaves from different shoot types. Our study represents the first comparative biometric analysis of the three Zelkova species localized in the western edge of the current geographic range of the genus. We found that the species differed from each other both, in terms of leaf form characters and level of leaf variation. Zelkova carpinifolia was clearly different from Z. abelicea, while the two populations of Z. sicula, SIB and SIA, were more similar to Z. carpinifolia and Z. abelicea, respectively. The latter finding supports the results of recent molecular studies suggestingt he hybrid origin of Z. sicula. Zelkova abelicea, Z. sicula and Z. carpinifolia differ each other in the leaf characteristics and level of phenotypic variation.

Zelkova schneideriana Hand.-Mazz. of the Ulmaceae family is a Tertiary relict and economically deciduous tree species endemic to Central and Southern China. In this study, we performed a transcriptome sequencing of Z. schneideriana using high-throughput sequencing approach to detect polymorphic expressed sequence tag-simple sequence repeats (EST-SSR) markers. A total of 3,235 microsatellite loci were detected from 53,517 unigenes. A set of 30 microsatellite markers were randomly selected to validate in 41 individuals from three populations, of which 10 were polymorphic. The number of alleles per locus ranged from 3 to 11. The observed heterozygosity and expected heterozygosity ranged from 0.366 to 0.829 and 0.439 to 0.848, respectively. These polymorphic SSR primers showed good transferability across different Zelkova species, and are valuable for future studies on genetic diversity, conservation, phylogeography, and species delimitation in Z. schneideriana, as well as other Zelkova species. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02968-5.

1. We clarified the effects of early leaf abscission on the survivorship of the leaf‐mining beetle Trachys yanoi Y. Kurosawa (Coleoptera: Buprestidae) and the underlying mechanism in relation to weather conditions in Japan. Trachys yanoi is an insect pest of zelkova trees [Zelkova serrata (Thunb.) Makino (Rosales: Ulmaceae)]. Larvae burrow into zelkova leaves and feed on leaf tissue, causing early leaf abscission. 2. This study investigated the relationship between the beetle population and weather conditions over 10 years in a zelkova forest. The effects of moisture and temperature on adult emergence from early abscised leaves were examined in the laboratory and in the field. 3. The beetle population in the studied forest was negatively affected by high precipitation levels when the beetles still inhabited early abscised leaves. Fewer adults emerged from early abscised leaves under wet conditions than under dry conditions, in both laboratory and field tests. 4. These results demonstrate that early leaf abscission plays an important role in leaf‐mining beetle survivorship and population dynamics, and that the amount of precipitation when leaf‐mining beetles still inhabit early abscised leaves modulates this effect. 5. Because precipitation when leaf‐mining beetles still inhabit early abscised leaves was mainly driven by an East Asian rainy season front, the beetle population dynamics were affected by the activity of the front.

В Армении встречаются представители трех родов семейства Ulmaceae: род Ulmus L., представлен 4 видами, род Celtis L. – 3, а род Zelkova Spach – 1. В статье приводятся сведения об условиях произрастания и роспространении, а также ключи для определения видов данных родов., In Armenia are grown represent of three genera of family Ulmaceae: the genera Ulmus L. represented by 4 species, the genera Celtis L. – 3, and the genera Zelkova Spach – 1. Data on habitats and distribution, and keys for definition of species of these genera are given.

PREMISE: Seed dispersal is extremely important for the recovery and restoration of forest communities. Relict tree genus Zelkova possesses a unique dispersal mechanism: mature fruits fall with the entire twig, and the dried leaves that are still attached function as a drag-enhancing appendage, carrying the fruits away from the parent tree. This singular adaptation has never been investigated in Z. abelicea. METHODS: Drop tests with dispersal units and individual fruits of Z. abelicea were performed in controlled conditions to measure their dispersal velocity and to define their flight mode.RESULTS: Zelkova abelicea utilizes both slowly falling dispersal units with chaotic motion, as well as fast falling individual fruits using the straight path. The falling velocity of Z. abelicea dispersal units is 1.53 m s-1, which is virtually identical to that of the East-Asiatic Z. serrata (1.51 m s-1). In contrast, the falling velocity of individual fruits was m s-1 (Z. serrata:5.36 m s-1).CONCLUSIONS: Members of the genus Zelkova, growing today in distant regions, show remarkable evolutionary conservation of the velocity and flight mechanics of their dispersal units. This is surprising since the Mediterranean and East Asiatic Zelkova species have been separated at least 15-20 Mya. Zelkova abelicea, although growing in the Mediterranean with completely different forest structure and composition, still uses the same dispersal mechanism. The dispersal capacity of the genus Zelkova is less efficient than that of other wind dispersed trees, and it presumably evolved for short-distance ecological spread and not for long-distance biogeographical dispersal.

The complete chloroplast genome sequence of the Tertiary relict tree Zelkova serrata was reported in this study. The chloroplast genome is 158,875 bp in length with a typical angiosperm quantitative structure consisting of a large single copy (87,412 bp) and a small single copy (18,683 bp) separated by a pair of inverted repeat (26,390 bp). Genome annotation revealed a total of 129 genes comprising 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenomic analysis based on the whole plastomes indicated that Z. serrata and Z. schneideriana formed a well-supported monophyletic clade sister to genus Ulmus in Ulmaceae.

Xylem and phloem sap flows in an intact, young Japanese zelkova tree (Zelkova serrata (Thunb.) Makino) growing outdoors were measured using magnetic resonance imaging (MRI). Two propagator-based sequences were developed for q-space imaging: pulse field gradient (PFG) with spin echo (PFG-SE) and stimulated echo (PFG-STE), which were used for xylem and phloem flow measurements, respectively. The data evaluation methods were improved to image fast xylem flow and slow phloem flow. Measurements were taken every 2–3 h for several consecutive days in August 2016, and diurnal changes in xylem and phloem sap flows in a cross-section of the trunk were quantified at a resolution of 1 mm2. During the day, apparent xylem flow volume exhibited a typical diurnal pattern following a vapor pressure deficit. The velocity mapping of xylem sap flow across the trunk cross section revealed that the greatest flow volume was found in current-year earlywood that had differentiated in April–May. The combined xylem flow in the 1- and 2-year-old annual rings also contributed to one-third of total sap flow. In the phloem, downward sap flow did not exhibit diurnal changes. This novel application of MRI in visualization of xylem and phloem sap flow by MRI is a promising tool for in vivo study of water transport in mature trees.

A new fossil species of Zelkova is described from the Oligocene Ningming Formation of Guangxi, South China. Zelkova ningmingensis sp. nov. is characterized by leaves with craspedodromous venation pattern and drupaceous fruit type. The new species possesses elliptical to ovate leaves, bearing 7–12 pairs of secondary and simple toothed margin, as well as epidermal cells with straight or rounded anticlinal walls. The species is compared with extant and other fossil species hitherto reported of the genus. It is most similar to the living Zelkova schneideriana in the leaf gross morphology and epidermal characters, which may be suggested to be the ancestral type of Zelkova schneideriana. The discovery of Zelkova ningmingensis sp. nov. in Guangxi indicates that Zelkova has already existed in southern China as early as the Oligocene. In combination with Zelkova material from the Oligocene of Europe, it can be inferred that Eurasian Zelkova had begun to diversify by at least the Oligocene. Because China is the bio...

Zelkova species, trees of the elm family (Ulmaceae), are part of the Cenozoic relict flora. In western Eurasia, the genus comprises three species that are restricted to disjunct areas (Z. sicula on Sicily, Z. abelicea on Crete and Z. carpinifolia in Transcaucasia). The situation is different in East Asia, where three species (Z. serrata, Z. schneideriana and Z. sinica) have at least partly overlapping distributions. The phylogenetic and phylogeographic status of these East Asian species is still not well understood, mainly since all previous studies used almost exclusively plant material collected in botanical gardens and were based on very small numbers of individuals. Our study is the first based on 33 natural populations covering all important areas with Zelkova species in the Sino-Japanese Floristic Region. Chloroplast and microsatellite markers were used, and Bayesian analyses were run for both types of markers. East Asian Zelkova species cluster into two groups that partially overlap when comparing the two types of markers. For chloroplast markers, the two groups coincide with all Japanese, some Korean and northern Chinese Z. serrata in one group and all other individuals in the other group, regardless of whether they are attributed to Z. serrata, Z. sinica or Z. schneideriana from Korea, mainland China and Taiwan. At the nuclear level, however, the clustering clearly groups all the Z. serrata individuals together, regardless of whether they are from Japan, Korea or China, and the two other species in a second group. This complex genetic pattern in East Asian Zelkova species is most likely due to a combination of ancient diversification and speciation events and more recent hybridization during the last glacial/interglacial retractions and recolonizations. One of the surprising results of our study concerns the populations from Taiwan, which are genetically similar to Z. schneideriana. Thus, their assignation to a separate taxon (Z. tarokoensis) or to a variety of Z. serrata (Z. serrata var. tarokoensis), as currently reported in all local and national floras, might be in need of revision. Furthermore, our results indicate that the East Asian species are more closely related to Z. carpinifolia than to any other Western European species. Haplotypes of Z. sicula and Z. abelicea (Mediterranean region) as well as those of Z. sinica and Z. schneideriana (East Asia) seem to have diversified more recently. The most ancient haplotypes are found among the western Eurasian Z. carpinifolia and the East Asian Z. serrata. This result is in agreement with the carpinifolia and serrata-like morphotypes commonly found in the fossil record.

We reported the complete chloroplast genome for Zelkova serrata, the first in the distinctive genus Zelkova to be sequenced in the family Ulmaceae. The plastome is totally 158,495 bp in length, containing a pair of inverted repeats (IRs), a large single-copy region (LSR) and a small single-copy region (SSR), which are 26,456 bp, 86,921 bp and 18,684 bp, respectively. A total of 103 unique genes were identified in Z. serrata chloroplast genome, of which 88 are single-copy genes, while15 are duplicated in IR regions. Further, maximum-likelihood phylogenetic analyses were conducted using eight complete plastomes of the Ulmaceae, which support close relationships between Z. serrata, Ulmus gaussenii, and U. chenmoui.

Botanic gardens and arboreta, particularly in regions where iconic relict trees naturally occur, play a vital role in the conservation of these species. Maintaining well- managed living ex situ collections of rare and threatened relict tree species provides an immediate insurance policy for the future species conservation. The aim of this research was to investigate the origin, representativeness and genetic diversity of relict trees kept in botanic gardens and arboreta. We used as a model two ecologically and biogeographically distinct members of the prominent relict genus Zelkova (Ulmaceae), which survived the last glaciation in disjunct and isolated refugial regions: Z. carpinifolia in Transcaucasia and Z. abelicea endemic to Crete (Greece) in the Mediterranean. Our study revealed substantial differences in the genetic diversity and the origin of living ex situ collections of the two

Aim To elucidate the phylogeographical patterns in three Cenozoic relict species: Zelkova sicula, Z. abelicea and Z. carpinifolia (Ulmaceae). Location Sicily, Crete and Transcaucasia. Methods Two chloroplast loci (trnH–psbA and trnL) and the nuclear ribosomal markers ITS1 and ITS2 were sequenced for 154 samples collected from 14 populations of Z. abelicea, 16 populations of Z. carpinifolia, and the two known populations of Z. sicula. We obtained georeferenced data, calculated median joining networks and carried out diversity analyses. A few ex situ samples collected from botanical gardens, of the East Asian species Zelkova serrata, Z. schneideriana and Z. sinica, were also analysed for comparative purposes. Results High levels of variability were found in the chloroplast markers within Z. carpinifolia (15 haplotypes) and Z. abelicea (33 haplotypes), in association with strong phylogeographical structure. Conversely, Z. sicula was characterized by low diversity, with each population exhibiting a single haplotype. Lower variability was found for ITS1 and ITS2 within Z. carpinifolia and Z. abelicea (13 and 7 ribotypes per species, respectively), with Z. carpinifolia showing a high proportion of populations with no intragenomic polymorphism. In the triploid and clonal Z. sicula, all individuals displayed intragenomic polymorphism and seven ribotypes were identified. Main conclusions The chloroplast diversity of Z. abelicea and Z. carpinifolia suggests a very ancient history of diversification and structuring, with footprints of past expansions and more recent bottlenecks. Zelkova sicula has had a history of severe isolation and is likely to be of hybrid origin.

Lymantria (Lymantria) lucescens (Butler) collections and observations were made at Toyota and Azumino, Honshu, Japan. Larvae are now recorded to feed on Fagaceae (Quercus, four species); Ulmaceae (Ulmus and Zelkova) and Moraceae (Morus). During the moth flight (July in Toyota), both sexes (but only 15% females) were attracted to commercial lighting and settled on lit surfaces such as storefronts. Females (wingspan av. 72 mm) carried on average 758 eggs each. Periodicity of male moths responding to either synthetic sex pheromone or to visible lights showed that flight activity peaked between 2000 and 2100 h. Three different larval parasitoids from L. lucescens were recovered. L. lucescens is discussed in light of attributes favoring its potential invasiveness.

Maintaining living ex situ collections is one of the key conservation methods in botanic gardens worldwide. Despite of the existence of many other conservation approaches used nowadays, it offers for many endangered plants an important insurance policy for the future, especially for rare and threatened relict trees. The aim of this research was to investigate the global extent of living ex situ collections, to assess and discuss their viability and inform the development of conservation approaches that respond to latest global conservation challenges. We used as a model taxon the tree genus Zelkova (Ulmaceae). The genus includes six prominent Tertiary relict trees which survived the last glaciation in disjunct and isolated refugial regions. Our comprehensive worldwide survey shows that the majority of botanic institutions with Zelkova collections are in countries with a strong horticultural tradition and not in locations of their origin. More importantly, the acutely threatened Zelkova species are not the most represented in collections, and thus safeguarded through ex situ conservation. Less than 20% of the ex situ collections surveyed contain plant material of known wild provenance while the majority (90%) of collections are generally very small (1–10 trees). Botanic gardens and arboreta particularly in regions where iconic relict trees naturally occur should play a vital role in the conservation of these species. The coordination of conservation efforts between gardens has to be enhanced to prioritise action for the most threatened relict trees. Large scale genetic studies should be undertaken, ideally at genus level, in order to verify or clarify the provenance of ex situ collections of relict trees in cultivation. For the most threatened relict tree genera, well-coordinated specialist groups should be created.

To address the evolution and geographical diversification of the genus Zelkova (Ulmaceae) a phylogenetic analysis of morphological data and the sequences of the internal transcribed spacers (ITS1 and ITS2) of nuclear ribosomal DNA were used. Cladistic analyses suggested that the Chinese species Z. schneideriana and Z. sinica are basal within Zelkova. The western Asian Z. carpinifolia either appears nested between the East Asian Z. schneideriana and Z. sinica and a clade formed by the Japanese Z. serrata and two Mediterranean species, Z. abelicea and Z. sicula (ITS), or forms a clade with Z. serrata that is sister to a clade Z. abelicea plus Z. sicula (morphology). Nucleotide data suggested that gene flow occurred between Z. schneideriana and Z. serrata, and Z. carpinifolia and a lineage ancestral to Z. abelicea/sicula. Character evolution in Zelkova appears to have gone from long leaves with numerous secondary veins, coarse to shallow teeth with blunt or slightly pointed apex and small stomata, to leaves that are either long or short with numerous or few secondary veins, coarse teeth with cuspidate or obtuse apex or conspicuously shallow teeth, and dimorphic stomata displaying ‘giant stomata’ surrounded by a ring of small stomata or uniform large stomata. These results are in agreement with fossil data. Early Cainozoic fossils attributed to Zelkova from North America and Central Asia closely resemble the modern Z. schneideriana and Z. carpinifolia. The genus could have originated in the northern Pacific area and migrated to Europe after the Turgai Strait was closed during the Late Oligocene. Geographical differentiation may have started with the isolation of Chinese populations (leading to modern Z. schneideriana and Z. sinica) from high-latitude Eurasian (North American) populations. This widespread Early Cainozoic type may have diversified into the western Asian Z. carpinifolia and the more derived Japanese and Mediterranean species during the latest Cainozoic. The modern Japanese and European/western Asian species would have differentiated relatively late, while two locally endemic Mediterranean species are the result of the cooling and development of a Mediterranean climate belt in Europe during the Pleistocene. Fossils from the Miocene and Pliocene of Europe resemble modern Z. carpinifolia and Z. serrata. Differentiation of the two Mediterranean species Z. abelicea and Z. sicula in the Late Cainozoic cannot be traced by leaf morphology. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 147, 129‐157. ADDITIONAL KEYWORDS: character evolution ‐ ITS1 ‐ ITS2 ‐ molecular evolution ‐ pattern evolution ‐ speciation.

Two European species belong to the genus Zelkova: Z. abelicea Boisser, endemic to the island of Crete, and Z. sicula Di Pasquale, Garfi and Quezel, endemic to Sicily. Nuclear DNA markers (ISSR and AFLP) were analysed in the two species. Results showed genetic variation within the Z. abelicea population but not within the Z. sicula population. This species, existing as a unique population, revealed to be represented by a unique genotype, which is not present in the Z. abelicea sampling, thus indicating that an extreme reduction of genetic variability characterises Z. sicula. Based on this result, we can assume that agamic propagation is the reproductive strategy of this species in its present environment, unfavourable to the development of regular and functional flowering structures. The priorities for conservation programs are discussed in the light of the different genetic resources represented by the two taxa.

Summary • The distribution of intervascular pit membranes with a torus was investigated in juvenile wood samples of 19 species of Ulmus and seven related genera. •A staining solution of safranin and alcian blue (35 : 65) was recommended to distinguish torus-bearing pit membranes using light microscopy. • Intervascular pit membranes connecting relatively wide vessel elements resembled those of most angiosperms, as they were of uniform thickness. By contrast, bordered pit pairs with round to oval pit apertures and indistinct pit canals that connected narrow (incomplete) vessel elements or vascular tracheids with distinct helical thickenings were frequently characterized by a torus in ring-porous wood samples of Ulmus and Zelkova . Tori were lacking in diffuse-porous species of Ampelocera , Aphananthe , Gironniera , Holoptelea , Phyllostylon , Trema and Ulmus . • Our observations suggest that tori are more common in cold temperate climates than in warm (sub)tropical environments. This may indicate that narrow tracheary elements with torus-bearing pit membranes provide an auxiliary conducting system which is of low conductivity, but offers greater resistance to freezing-induced cavitation.

Chloroplast (trnL) and ribosomal (ITS2)sequences and chloroplast DNA (PCR-RFLP andSSR) markers were analysed in two relicUlmaceae tree species: Zelkova abelicea,from Crete, and Z. sicula, from Sicily.The analysis of the plastidial trnLintron and of ITS2 ribosomal sequences revealedtheir divergence from the related speciesZ. carpinifolia, widespread in the Caucasianregion; one base substitution in the trnLintron was detected between the twoMediterranean species, thus suggesting theirrecent separation. Molecular markers(plastidial PCR-RFLP and SSR) showed an evidentgenetic differentiation between Z. siculaand Z. abelicea, the two species beingcharacterised by different haplotypes. Nowithin population variation was detected usingdifferent chloroplast markers inZ. abelicea and Z. sicula. Paleobotanicaldata proved that the genus Zelkova wasabundant and widespread in central Italy untilit became extinct in the continental part ofEurope during last glaciation events andsurvived only in two Mediterranean islands. Thesegregation of the two Mediterranean relicspecies might have occurred as a consequence ofthe strong reduction of their distribution andthe following geographic isolation. Geneticdrift may have determined the drastic reductionof within stand diversity as observed in othersmall, peripheral and geographically isolatedplant populations. The priorities forconservation programs are discussed in thelight of the different genetic resourcesrepresented by the two taxa.

Zelkova , with six extant species in Eurasia – three in East Asia ( Z. schneideriana , Z. serrata , Z. sinica ), one in south-western Asia ( Z. carpinifolia ) and two in southern Europe ( Z. abelicea , Z. sicula ) – was investigated with respect to leaf architecture and epidermal characters by LM and SEM. The leaf venation of Zelkova is relatively uniform, while leaf size and shape are highly variable. Characters such as teeth and epidermal cells, trichomes and stomata provide useful specific distinctions. Beginning in the Miocene, increasing aridity in Central Asia would appear to have been responsible for isolating the eastern Asiatic species from their European/western Asiatic counterparts. The European range underwent further changes in response to Quaternary climatic oscillations.

Pollen morphological characteristics of Zelkova sicula Di Pasquale, Garfi et Quezel and Z. carpinifolia (Pallas) Koch (Ulmaceae) are described. Z. sicula is a shrub species which was recently discovered on southeastern Sicily. Z. carpinifolia is the Zelkova species to which some European Tertiary to Quaternary leaf fossils have been attributed in recent studies. The new results were compared with the pollen morphological characteristics of some other Ulmaceae species such as Z. abelicea (Lamark) Boissier, Z. serrata (Thunberg) Makino, Ulmus glabra Hudson, U. laevis Pallas, U. minor Miller, and U. procera Salisbury. It was observed that Z. sicula usually possesses 5 to 6 pores, whereas the other Zelkova species normally have fewer than 5 pores. Higher frequencies of tetrads, a Y-mark on the proximal face, and a smoother exine sculpture (compared with other Zelkova species) were noted for pollen of Z. sicula. The equatorial diameter of Z. sicula was larger than every other Ulmaceae species, with a smaller P E ratio. Some of these differences can be explained by the triploid nature of Z. sicula, which is quite exceptional for Ulmaceae. Given these remarkable characteristics, it should be possible to recognise Z. sicula pollen grains in fossil pollen assemblages. It is thus anticipated that a more comprehensive pollen analytical study will lead to a revision of the Mediterranean phytogeographical history of the genus Zelkova.

In a number of plants, mostly woody, the components of the buds are arranged so that the laminae of the young leaves all face towards the same (upper) side of the bud, rather than towards the bud apex; in axillary buds they usually face towards the parent axis. This situation has been known for many years. For convenience, the general case is here called the rotated-lamina syndrome. There have been very few developmental investigations of how the laminae attain their unusual orientation, and these have come to different conclusions about cases in the Ulmaceae. This paper reports a detailed investigation of the syndrome in Ulmus glabra and Zelkova serrata, with comparative observations on other Ulmaceae, including cases in Celtis that do not exhibit the syndrome. The syndrome arises by different means in Ulmus and Zelkova. In Ulmus the leaf primordium is asymmetrical from the outset, the leaf blade region is obliquely dorsiventral from an early stage, and further asymmetrical growth of the leaf buttress rotates the whole leaf blade region into its final orientation as it develops. Individual shoots show heteroblastic development in progressing from bud scale to foliage leaf initiation, in increasing accentuation of the rotated-lamina syndrome, and in an increasing degree of dorsiventrality. In Zelkova, as previously described, the leaf blade region appears first as a radially symmetrical upgrowth, and it acquires dorsiventral symmetry directly in the rotated position. In Celtis spp. the lamina arises in a quite normal orientation, but reorients as it emerges from the bud. The leaf primordia of all species studied show asymmetry in other aspects, particularly in respect of stipule development, and these seem to be general features of the organisation of dorsiventral shoots. Key words: Ulmus, Zelkova, Celtis, leaf, development, dorsiventrality, lamina rotation.

Five types of Late Eocene woods from western Nebraska are described. Three of the woods have an anatomy comparable to extant genera: Robinia (Leguminosae), Zelkova (Ulmaceae), and Prunus s.l. (Rosaceae). The Robinia wood is the earliest wood record for the genus. One wood has a suite of features most similar to that found in the Juglandaceae, but its combination of characters is not diagnostic to tribe. This material indicates that unique character combinations occurred within the Juglandaceae during the Late Eocene. One wood is likely a legume, but it has a combination of features that occur today in at least four other families, and so it is not assigned to a family. As a group these woods indicate that climate in the Late Eocene of Nebraska was seasonal—the Robinia and Zelkova woods are markedly ring porous, the Juglandaceae-like wood is semi-ring porous, the two diffuse porous woods have small diameter vessels and a high vessel density.

In two associated families, Celtidaceae and Ulmaceae, vernation pattern (represented by spatial relationships between leaf lamina and stipules, the presence or absence of stipular fusion, lamina orientation, and lamina folding pattern) is consistent within a genus but shows a significant diversity within a family. Six vernation types are distinguishable and tentatively named: 1) Celtis type (Aphananthe, Celtis, Lozanella, Parasponia, Pteroceltis, Trema), 2) Chaetachme type (Chaetachme), 3) Gironniera type (Gironniera), 4) Holoptelea type (Ampelocera, Holoptelea, Phyllostylon), 5) Zelkova type (Hemiptelea, Planera, Zelkova), and 6) Ulmus type (Ulmus). The former three types (found in most of celtidaceous genera) possess free or fused stipules inside of the lamina; in contrast, the latter three types (found in all six ulmaceous genera andAmpelocera) are characterized by having the free stipules outside of the lamina. Within Celtidaceae, Celtis type is probably primitive in having free stipules and an ordinarily oriented lamina; Chaetachme type (with fused, convolute stipules and obliquely oriented laminas) and Gironniera type (with laterally oriented laminas) are the derived. Likewise, within Ulmaceae, both Zelkova and Ulmus types (with laterally oriented laminas) are the derived, while Holoptelea type (with ordinarily oriented laminas) is primitive. Comparisons in vernation pattern suggest the distinctness of Celtidaceae from Ulmaceae and the isolated position ofAmpelocera.

The micromorphology of pits in tracheary elements was examined in 35 species representing 29 genera of Rosaceae and related families to evaluate the assumption that angiosperm pits are largely invariant. In most Rosaceae, pit membranes between fibers and tracheids frequently appear to have amorphous thickenings with an irregular distribution. Although these structures are torus-like under the light microscope, observations by electron microscopy illustrate that they represent "pseudotori" or plasmodesmata-associated thickenings. These thickenings frequently extend from the periphery of the pit membrane and form a cap-like, hollow structure. Pseudotori are occasionally found in few Elaeagnaceae and Rhamnaceae and appear to be related to species with fiber-tracheids and/or tracheids. True tori are strongly associated with round to oval pit apertures and are consistently present in narrow tracheary elements of Cercocarpus (Rosaceae), Planera (Ulmaceae), and ring-porous species of Ulmus and Zelkova (Ulmaceae). Vestured pits with homogenous pit membranes are reported for Hemiptelea (Ulmaceae). The homoplastic nature of pit membrane characteristics may be related to functional adaptations in terms of safety and efficiency of water transport or may reflect different developmental processes of xylem elements. These observations illustrate that there is more variation in angiosperm pits than previously thought.

The organic chemical profiles of fossil Acer and Quercus leaf tissues are presented and correlated with those of previously described fossil Celtis, Ulmus and Zelkova and interpreted in conjunction with referable extant genera. Intrageneric comparisons among fossil and extant taxa indicate that relatively minor phytochemical differences exist suggesting that little flavonoid and steroid evolution since post-Miocene times has occurred. Biosystematic relationships between living North American and Asian genera indicate that in some cases (Quercus, Zelkova) a greater affinity exists between living Asiatic species and elements of the Succor Creek Flora. The chemical data are proposed as an independent parameter in assessing angiosperm biogeography and proposed migration patterns of the Fagaceae and Ulmaceae. The high chemical fidelity seen between some living and fossil genera preserved in ash-fall deposits is ascribed to the reaction of membrane bound lipids with various organic acids and to subsequent rapid dehydration. THE chemical profiles of plant and animal fossils and of organic-rich sediments are affected by various physical and chemical factors that collectively alter their original biochemistry (Jones and Vallentyne, 1960; Kvenvolden, 1966; Brooks, 1971). While chemical data may provide some basis for deducing a fossil's original biochemistry, and thereby provide broad taxonomic inferences (Niklas, 1976; Niklas and Gensel, 1977), diagenesis generally prevents direct comparisons between extant and fossil taxa thought to be related on the basis of morphology or anatomy. The degree of diagenesis may to some extent be determined by the presence of various organic constituents known to be labile, unstable, or thermometric. This is particularly true if the fossil taxon has a putative extant representative. In this paper we present the organic chemical profiles of five angiosperm genera representative of the Succor Creek Flora of Miocene age (Graham, 1963, 1965; Taggart and Cross, 1975). Previous reports have shown that leaf tissues isolated from volcanic ash-fall lenses show only

Organic solvent extractions of Zelkova oregoniana, a Miocene angiosperm compression fossil, indicate the chemical preservation of kaempferol, dihydrokaempferol, an n-alkane chain length range of 10 to 32 carbons, hydroxy acids, steranes, triterpenoids, and methyl pheophorbide a. This appears to be the oldest occurrence of flavonoids in fossil sediments reported.