Paleobotanical studies inFagaceae of the European Tertiary

A systematic reassessment of megafossil records ofFagaceae in Central Europe has been undertaken on the basis of leaf cuticular characters. The oldest representatives date back to the Eocene:Quercus subhercynica spec. nova,Dryophyllum furcinerve (Rossm.)Schmalh.,Trigonobalanopsis rhamnoides (Rossm.) gen. & comb. nov. In the Oligocene other members of extant genera appear:Quercus rhenana (Weyl. & Kilpp.)Knobloch & Kvaek,Fagus attenuata Goepp.,Lithocarpus saxonicus spec. nova. In the Neogene these ancient taxa (except inFagus lineage), are gradually replaced by deciduous species ofQuercus andCastanea. Trigonobalanus andCastanopsis are recorded by fruits (or wood) only.     

Pollination disruption by European honeybees in the Australian bird-pollinated shrubGrevillea barklyana (Proteaceae)

European honeybees (Apis mellifera) were less efficient pollinators ofGrevillea barklyana than nectar-feeding birds. Nectar-collecting honeybees did not contact reproductive parts of flowers. Pollen-collecting honeybees preferentially visited malestage flowers but rarely visited female-stage flowers. Fruit set on caged inflorescences that allowed access to honeybees but excluded birds was reduced by more than 50% compared to inflorescences that were visited by both types of visitors. Further, fruit set on caged inflorescences was less than on bagged inflorescences that excluded both birds and honeybees, indicating that pollen removal by bees decreased opportunities for delayed autonomous selfing in the absence of birds. Although fruit set was not pollen-limited at the study site, pollen removal by honeybees would decrease fruit set in small populations where birds are scarce. In addition, pollen removal by honeybees would reduce opportunities for outcrossing and reproductive success through male function. Although honeybees have been in Australia for insufficient time to have exerted selection on floral traits, evolutionary shifts in response to these animals are likely to occur in the future.     

Evolution of the translator inPeriplocaceae andAsclepiadaceae

This paper deals with the problem of homology between the translators inPeriplocaceae andAsclepiadaceae. Since most differences between the flowers in both families are based on the functional differences in the pollination process, it seems that the question of common ancestry can best be solved by clarifying the problem of the evolution of the translator itself. Ontogenetic investigation has revealed that the central element of the periplocoid translator is the adhesive disc together with the base of the stipe. The translator inSecamoneae (the most primitive tribe inAsclepiadaceae) is homologous to this element, and inSecamone the adhesive disc is transformed into the corpusculum while the stipe is represented by the dorsal process to which the pollinia are attached. The translator in the genusFockea represents an intermediate stage in the further phylogenetic elaboration of the asclepiad translator. It corresponds toSecamone in the development of a dorsal process for the attachment of the pollinia and in the special mode by which the corpusculum is attached to the anther wings. On the other hand, the elongated shape and the formation of a floor in the corpusculum are derived traits pointing to the more highly evolvedAsclepiadaceae, such as theAsclepiadeae. The question of the derivation of the caudicles is discussed and a hypothesis concerning their development from pre-adaptive elements inFockea is put forward. General conclusions are 1. thatPeriplocaceae andAsclepiadaceae are sister groups and that the common ancestor possessed a primitive translator composed of at least the two elements adhesive disc and stipe; 2. that the morphological difference of the translators betweenPeriplocaceae andSecamone is smaller than betweenSecamone and the more advancedAsclepiadaceae.

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Zusammenfassung Ein wesentlicher Unterschied zwischen den beiden FamilienPeriplocaceae undAsclepiadaceae besteht in der Ausbildung der Translatoren, mit deren Hilfe der Pollen von Insekten übertragen wird. Bei denPeriplocaceae kleben die Pollentetraden an dem Translator, dieser selbst haftet mit einer basalen Klebscheibe am Kopf des Pollinators. DieAsclepiadaceae verzichten demgegenüber auf den Klebstoff, die Pollinien sind durch zwei Caudiculae mit einem Klemmkörper verbunden, der am Insekt klemmt. Im Zentrum dieser Arbeit steht die Frage, ob sich zwischen beiden Translatorformen Homologien finden lassen, die eine gemeinsame stammesgeschichtliche Herkunft begründen.Der Translator derPeriplocaceae besteht aus den drei Elementen Klebscheibe (adhesive disc), Stipes (stipe) und Pollenschaufel (spoon). Im typischen Fall sitzt der Stipes dorsal der Klebscheibe an, wodurch die Klebfläche selbst wie ein Stempel nach unten bzw. schräg nach außen gerichtet ist. Demgegenüber ist die geradlinige Anordnung von Stipes und Klebscheibe beiPeriploca graeca eine Ausnahme, die nicht als Basis für den Vergleich mit dem Asclepiadaceen-Translator dienen kann. In der Ontogenese wird der feste Teil der Klebscheibe, das Scutellum, zuerst angelegt und durch basale Sekretaddition als etwa rechtwinklig zur Griffelkopfoberfläche stehende Scheibe hinausgeschoben. Die Bildung des Scutellums erfolgt also von seiner Schmalseite aus. Im nächsten Schritt wird der Stipes-Ansatz am Scutellumrücken gebildet, auf diese Weise entsteht die gewinkelte Verbindung von Klebscheibe und Stipes. Der Anschluß der Pollenschaufel erfolgt etwas später ebenso wie die basale Verlängerung der Klebscheibe. Die Ontogenese zeigt, daß das primäre Element des Periplocaceen-Translators der obere Teil der Klebscheibe mit dem ihm dorsal ansitzenden basalen Stipesabschnitt ist.Innerhalb derAsclepiadaceae bilden die GattungenSecamone undFockea von den übrigen Gattungen abweichend gestaltete Translatoren aus, bei denen die Pollinien nicht an seitlichen Caudiculae, sondern an einer dorsalen Platte befestigt sind. Der morphologische Vergleich ergibt, daß die Translatoren beider Gattungen ausgeprägt plesiomorphe Züge tragen und als Zwischenformen zwischen dem Periplocaceen-Translator und dem elaborierten Asclepiadaceen-Translator angesehen werden können. Der Translator vonSecamone läßt sich mit dem primären Scutellum-Stipes-Komplex derPeriplocaceae homologisieren. Der Klemmkörper selbst entspricht einem nach vorn zusammengeschlagenen Scutellum, der die Pollinien tragende Dorsalfortsatz dem basalen Stipes.Für diese Homologisierung spricht nicht nur die relative Lage der Elemente der verglichenen Translatoren, sondern insbesondere ihre in den Grundzügen übereinstimmende Ontogenese. Von ausschlaggebender Bedeutung ist dabei die von der Schmalseite her erfolgende Bildung des Scutellums, die in der von der Basis aus fortschreitenden Anlegung desSecamone-Klemmkörpers ihre Entsprechung findet.Der Translator der GattungFockea stellt im Sinn des Stetigkeitskriteriums eine Zwischenform zwischen denSecamoneae und den elaboriertenAsclepiadaceae dar. Ohne diese Zwischenform wäre der morphologische Zusammenhang der Translatoren beider Taxa kaum zu belegen.Fockea stimmt mitSecamone in der Ausbildung des dorsalen Fortsatzes zur Pollinienanheftung wie auch in der Anheftung des adulten Translators an die Leitschiene mit Hilfe basaler Klebflächen überein. Eine Weiterentwicklung zeigtFockea in der Verlängerung des Translators parallel zur Griffelkopfoberfläche, die mit einer anfänglichen neuen Bodenbildung einhergeht. Diese neue Längsachse wie auch eine ausgeprägte Bodenstruktur sind charakteristisch für die Translatoren höher entwickelter Asclepiadaceen. Als auffälligstes Unterscheidungsmerkmal kommt bei ihnen die Befestigung der Pollinien mit Hilfe zweier Caudiculae hinzu. Aufgrund fehlender Zwischenstufen ist die phylogenetische Herkunft der Caudiculae bisher nur hypothetisch lösbar. Eine Ableitung von basalen Klebflächen wie etwa beiFockea wird für wahrscheinlich gehalten.Damit sind im elaborierten Asclepiadaceen-Translator nur noch Andeutungen von Elementen zu finden, die mit dem Translator vonSecamone homologisiert werden könnten. Nach den vorliegenden Untersuchungen erscheint der Entwicklungsschritt von der Periplocaceen-Stufe zum einfachsten Klemmkörper derAsclepiadaceae beiSecamone wesentlich geringer als die Evolution des Translators innerhalb derAsclepiadaceae selbst.

     

A further note on the relationships of the EuropeanLinum hologynum and the Australian species ofLinum (Linaceae)

The diploid chromosome number for the EuropeanLinum hologynum and the haploid number for the AustralianL. monogynum is 42 and appears to establish a new and distinctive base number for sect.Linum. The possession by these two species and by the AustralianL. marginale of multiporate pollen and united styles, a unique combination of features in sect.Linum, may warrant the establishment of a new subsection in that section to accommodate the three species.     

Pollen evolution and systematics inAnnonaceae with special reference to the disulcate Australian endemic genera

All genera ofAnnonaceae endemic in Australia (Ancana, Fitzalania, Haplostichanthus) show almost exactly the same type of disulcate (disulculate) pollen with intact exine extending over the sulci. Tetrad stages inHaplostichanthus andAncana reveal a latudinal subequatiorial orientation of the two sulci at the proximal hemisphere. Sometimes they fuse into a ±zonosulcate aperture.Fissistigma pollen grains are ±globose and have a flattened pole with a central elevation and a concentric groove, covered by a somewhat reduced exine. This palynological characters give further support for separating the generaAncana andFissistigma. Germination was observed inHaplostichanthus where the pollen tube emerges at one of the two sulci and inFissistigma where the flattened part breaks up during germination. The aperture types described here are obviously transitional stages between aperturate and inaperturate pollen grains and are discussed in regard to pollen evolution.     

Some aspects of dioecy inOcotea (Lauraceae)

The evolution of dioecy inLauraceae cannot be attributed to selection for outbreeding but must have other reasons. Therefore it is interesting to note that inOcotea there seems to be a correlation between mode of reproduction and geographical distribution.     

Multivariate morphometric and allozymic analysis of theConospermum taxifolium (Proteaceae) species complex

A morphometric analysis of 18 attributes of 110 plants of theConospermum taxifolium complex suggests that it consists of three polythetically distinct taxa, corresponding to the traditional concepts ofC. taxifolium Smith s. str.,C. ericifolium Smith andC. ellipticum Smith. Discrimination is possible on the basis of leaf but not flower attributes. Analysis of allozymic variation indicates that the taxa are also genotypically differentiated.C. ericifolium andC. ellipticum are geographically isolated from each other but not fromC. taxifolium, andC. taxifolium is usually ecologically segregated from the other two taxa. Where this ecological segregation breaks down, morphological intermediates sometimes occur as the result of hybridization.     

Chromosome numbers of Western Australian species ofVillarsia (Menyanthaceae)

Chromosome numbers are reported for eight of the nine Western AustralianVillarsia species.Villarsia albiflora, V. calthifolia, V. capitata, V. congestiflora, V. lasiosperma, V. latifolia, andV. violifolia are diploid with n=9. Five populations ofV. parnassiifolia are diploid and three are tetraploid (n=18). The morphological, ecological, and breeding-system diversity of the Western Australian species is largely not associated with the tetraploidy or hexaploidy that characterizes otherVillarsia species in eastern Australia and South Africa. The majority of Western AustralianVillarsia species are restricted to the high rainfall zone of southwestern Western Australia, where favorable climatic and edaphic conditions may have existed since mid-late Tertiary times.     

Ecogeographical differentiation of the Submediterranean deciduous forest flora

The deciduous wood flora of southern Europe is characterized as a special nemoral-Submediterranean element. The distribution patterns of some representatives (total ranges and local areas in Roumania) are described and explained by recent climatic conditions. The northern limits of Submediterranean and Submediterranean-middle European deciduous forest taxa exhibit a continuous gradation, but only a few species with a wide ecological amplitude extend into the temperate zone.     

Early history of theJuglandaceae

The major radiation of theJuglandaceae occurred during the early Tertiary as recorded by the proliferation of juglandaceous pollen and the appearance of fruits representing extinct and extant genera of the family. Juglandaceous pollen types of the Paleocene were predominantly triporate and exhibited a greater diversity in patterns of exinous thinning than occurs in the family today. Analyses of in situ pollen from early Tertiary juglandaceous inflorescences confirms the taxonomic value of certain patterns of exinous thinning. Data from co-occurring fruits and pollen indicate that relatively unspecialized, isopolar triporate pollen of the type presently confined to the tribeEngelhardieae also occurred in other tribes of the family during the Paleocene. Pollination has been mostly anemophilous throughout the Tertiary. Both wind and animal fruit-dispersal syndromes were established early in the radiation of the family but a greater diversity of wind-dispersed genera has prevailed.     

Evolution of the tetraploidCapsella bursa-pastoris (Brassicaceae): Isoelectric focusing analysis of Rubisco

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) and its subunits (large subunits = LSU, small subunits = SSU) were isolated from threeCapsella spp. by gel electrophoresis and polypeptide composition was analyzed by isoelectric focusing (IEF) in the presence of 8M urea. The described techniques are recommended for large scale systematic studies. Multiple IEF banding patterns of the SSU are probably the outcome of a heterogenous multigene family. The two diploid speciesC. rubella andC. grandiflora show an identical IEF pattern and could be differentiated from the putative allotetraploidC. bursa-pastoris only by the SSU banding pattern. Uniqueness of some SSU bands in the tetraploid and in the two diploid species, respectively, may indicate an ancient alloploid origin of tetraploidC. bursa-pastoris followed by events leading to divergences in the genomes of the allotetraploid and its presumed diploid progenitors after the hybridization event (SSU gene elimination, acquisition of new SSU genes).     

A brief review of the fossil history of the family Rosaceae with a focus on the Eocene Okanogan Highlands of eastern Washington State, USA, and British Columbia, Canada

Many of the oldest definitive members of the Rosaceae are present in the Eocene upland floras of the Okanogan Highlands of northeastern Washington State and British Columbia, Canada. Over a dozen rosaceous taxa representing extant and extinct genera of all four traditionally recognized subfamilies are known from flowers, fruits, wood, pollen, and especially leaves. The complexity seen in Eocene Rosaceae suggests that hybridization and polyploidy may have played a pivotal role in the early evolution of the family. Increased species diversity and the first appearance of additional modern taxa occur during the Late Paleogene in North America and Europe. The Rosaceae become increasingly important components of fossil floras during the Neogene, with taxa adapted to many habitats.     

Evolution of the secondary haustoria to a primary haustorium in the parasiticScrophulariaceae/Orobanchaceae

In the parasiticScrophulariaceae andOrobanchaceae, two types of contact organs exist: secondary and primary haustoria. Secondary haustoria are lateral organs, developing in large numbers and only when the seedling is fully established. In contrast, a primary haustorium represents the first developmental stage of the seedling itself. In the root system of the parasiticLesquereuxia syriaca (=Siphonostegia syriaca) there are only secondary haustoria, but a few of them apparently develop in a terminal position. This is achieved by transferring the haustorial initiation region closer to the root apex. One can interpret this as a transformation of the apical meristem into a meristematic haustorial tissue. On the condition that an extreme shortening (abbrevation) of the primary root could happen, we discuss the transformation of the terminal secondary into a primary haustorium.     

Characterization of the bacterial flora of mass cultivated Brachionus plicatilis

Bacterial density and composition in association of mass cultivated rotifers (Brachionus plicatilis, SINTEF-strain) was investigated, during experimental conditions identical to the procedures used for preparing rotifers as live food for marine cold water fish larvae. These procedures include cultivation, enrichment with squid meal and acclimation to low temperature by storage of the rotifer culture at 6 °C. Large variations were observed in the number of rotifer associated (1.8–7.6 · 10³ colony forming units per rotifer^–1) and free-living (0.6–25 10⁷ cells·ml^–1) bacteria. An increase of 50–150% in the bacterial number was normally observed after feeding the rotifer with squid meal, but after three days of acclimation at 6 °C, the bacterial numbers decreased to the initial level.After enrichment of the cultures with squid meal, the similarity in the composition of the bacterial flora between the rotifers and water was reduced. However, acclimation of the culture at 6 °C resulted in better agreement of the rotifer associated flora and that in water. Enrichment of the cultures induced a shift in the bacterial composition from Cytophaga/Flavobacterium dominance to Pseudomonas/Alcaligenes dominance. The bacterial flora of the rotifer cultures are dominated by presumably opportunistic species after enrichment, which may have detrimental effects when rotifers are fed as live food to marine fish larvae.     

Evolution of erect growth forms in domesticated wheats: possible effects of grazing

Summary Wild wheats tend to have a prostrate growthform during the early part of their vegetative growth phase. However, at a later stage the leaves and spike-bearing stalks change the pattern of growth and develop in an erect position. Domesticated wheats develop differently, with an erect growth form dominating the entire growth phase.It is suggested that heavy grazing, especially during early winter months might have played a role in the eradication of spontaneously appearing erect mutants of wild wheat. Such mutants increased in frequency only under domestication.     

Systematic analysis of Dendrobium Swartz section Dendrocoryne in the Australian region

Dendrobium sect. Dendrocoryne is a difficult taxonomic group of allied species and species complexes, occurring on the eastern Australian coastline, Lord Howe Island and New Caledonia. Significant morphological characters were assessed from all key areas of the distribution range. Patterns of variation between species, varieties and hybrids were investigated by principal coordinate analysis. The analyses affirm 12 species in the sect. Dendrocoryne described by Schlechter (1912, 1982) and Dockrill (1969, 1992), including a cluster of small statured D. gracilicaule, D. adae, D. fleckeri, and D. finniganense, and three variable species complexes – D. speciosum, D. kingianum and D. tetragonum. Recently described D. finniganense and D. callitrophilum are interpreted as members of the section. Phylogenetic relationships are presented based on parsimony analysis of 31 morphological characters. Analyses do not support proposals to recognize new genera for D. tetragonum, D. callitrophilum and D. aemulum, or to create new species within D. tetragonum, D. jonesii, D. speciosum and D. kingianum. The phylogeny indicates that rainforest taxa are earlier lineages and xerophytic taxa are more derived.     

Evolution ofPeperomia (Piperaceae) in the Juan Fernandez Islands,Chile

Four species ofPeperomia (Piperaceae) occur in the Juan Fernandez Islands, Chile:P. berteroana, P. margaritifera, P. skottsbergii, andP. fernandeziana. The last species is found also in continental Chile, whereas the other three are endemic to the archipelago.Peperomia margaritifera is found only on the older island of Masatierra, whereasP. skottsbergii is confined to the younger island of Masafuera, andP. berteroana occurs on both islands. Phenetic analyses of mainland taxa suggest thatP. fernandeziana belongs to subg.Sphaerocarpidium whereas the endemic taxa form their own subg.Tildenidium connecting to subg.Tildenia. Cladistic analyses indicate thatP. margaritifera is the most primitive species in the archipelago and thatP. berteroana is the most derived, especially patristically. Chromosomally, the four species are all n = 22, which may be tetraploid on a base of x = 11. Sulfated flavones occur only inP. berteroana andP. skottsbergii, which are otherwise unknown for the family. Dispersal of propagules to the islands from the continent and between islands is believed to have been accomplished by birds.     

Evolution,pollination, and systematics of the tribeNeottieae (Orchidaceae)

The various classifications of the orchid tribeNeottieae are reviewed and a new classification is proposed that divides the tribe into three subtribes,Neottiinae, Limodorinae, andCephalantherinae, based primarily on characters of the column (gynostemium). A cladistic analysis illustrates that these three subtribes are more closely related to one another than either is to any other group in subfam.Neottioideae, although there are very few apomorphic characters for the tribe. Pollination biology is also discussed showing links between breeding systems and distribution. There is also a possible role between column and labellum morphology and the emergence of a deceptive pollination syndrome from one of reward.     

Evolution alpiner Populationen vonEuphrasia (Scrophulariaceae): Die tetraploideE. minima

A systematic analysis of the variable and probably allotetraploidE. minima is presented, its infraspecific taxonomy is discussed.E. tatrae is provisionally included intoE. minima although some differences may exist;E. mendonçae may be a relic of a formerly wider distribution ofE. minima; E. willkommii seems to be closer toE. stricta s. lat. than toE. minima. 4x-E. minima is supposed to be derived from phylogenetic lines close to extant dwarf alpine forms of 2x-E. alpina (including its yellow flowering subsp.christii;Vitek 1985b) and 2x-E. hirtella (vgl.Vitek 1985a). Some characteristics (e.g., its small flowers) could have been introduced through hybrid introgression from other 2x-species, particularlyE. inopinata and/orE. sinuata (vgl.Ehrendorfer & Vitek 1984).     

The tubular exine ofLauraceae andHernandiaceae,a novel type of exine structure in seed plants

The pollen grains ofLauraceae andHernandiaceae are characteristic in having a tubular exine of ± microfibrillar structure. This is coated with a layer of medium electron-dense globules and very peculiar spines, made up of a substance differing from that of the exine. Such a pollen wall structure is otherwise unknown in seed plants and thus adds to the list of odd features erratically present in various taxa of the Ranalean complex.