Simulations of the Ontogeny of Spongiophyton, a Devonian Plant

Mathematical representations of the cellular organization anddimensions of Spongiophyton Krusel, a Middle Devonian thallophytewere projected by means of a computer to simulate patterns ofdevelopment and organization. Extrapolation of the cellularpatterns observed on the surface of the fossil may be comparedwith those derived from living plants of which the ontogenycan be directly observed. Spongiophyton is compared in thisrespect with the growth of Protosalvinia (an Upper Devonianplant of enigmatic affinity), Pellia (a thallose liverwort)and Cutleria (a brown alga). The growth pattern of Spongiophytondeveloped by computer shows a closer similarity to that of thepseudoparenchymatous alga Cutleria than to the truly parenchymatousPellia or the fossil Protosalvinia. Computer simulations ofthe growth process throw light on the affinity of Spongiophytonwhich cannot be derived from direct observation of the fossil.Broader applications of computer simulations of tissue organizationand gross morphology are suggested with regard to the studyof living and fossil plants.     

The Ultrastructure of the Spores of the Devonian Plant Parka decipiens

The ultrastructure of the spores of Parka decipiens Flemingwas investigated by SEM and TEM. The spores are shown to havea structured wall consisting of two distinct layers, one ofwhich exhibits a lamellate organization. The deposition of thespore wall by a tapetum is suggested to account for these lamellae.Comparison is made between the spore ultrastructure of Parkaand that of algae and bryophytes. It is suggested that the sporewall of Parka bears some similarities with the lamellate exinefound in the Hepaticae. Parka decipiens, Devonian, fossil, spore wall, ultrastructure, lamellae, tapetum     

Parka decipiens and land plant spore evolution

The morphology and ultrastructure of the spores of the enigmatic Lower Devonian plant Parka decipiens are briefly described and previous interpretations of the plant are discussed. It is suggested that the alete spores of Parka could have been haploid or diploid. The possibility that some early plant spores were diploid may be viewed as supporting the interpolation theory for the origin of alternation of generations in land plants. The spores of Parka may lie (in morphological and developmental terms) somewhere between the oospores produced by algae and the triradiate haploid spores of the bryophytes.     

Roles of the Af and Tl Genes in Pea Leaf Morphogenesis: Shoot Ontogeny and Leaf Development in the Heterozygotes

The wildtype leaf blade of Pisum sativum possesses proximalleaflets and distal tendrils, which may be altered by two recessivemutations that affect pinna morphology, afila (afaf) and tendrilless(tltl). Using morphological observations and SEM, the variationin leaf forms along the plant axis and leaf development werecharacterized for plants heterozygous at the Af and/or Tl loci.The Af and Tl genes interacted to affect many characteristicsof shoot ontogeny, including rate changes in leaf blade lengthand complexity increases, as well as time to flowering. TheAf gene retarded early vegetative development and acceleratedthe time to flowering. The leaf phenotypes of these heterozygousgenotypes were specified mainly by changes in the timing ofmajor developmental events. The data support the hypothesesthat both genes are heterochronic in nature and that the pealeaf blade consists of three genetically- and developmentally-determined regions: proximal, distal and terminal. Copyright2000 Annals of Botany Company Heterochrony, leaf development, shoot ontogeny, Pisum sativum L., garden pea, afila,tendrilless .     

Epidermal Structure and Stomatal Ontogeny in Some Eusporangiate Ferns

Cuticles, mature epidermis, and stomatal ontogeny in some speciesof the three genera of Ophioglossaceae and in Angiopteris evectawere studied. Development of stomata is perigenous in all Ophioglossaceaebut it is mesoperigenous (Piper type) in A. evecta.     

Taxonomic revision of the genus Cutleria proposing a new genus Mutimo to accommodate M. cylindricus (Cutleriaceae,Phaeophyceae)

Molecular phylogenetic analyses of representative Cutleria species using mitochondrial cox3, chloroplast psaA, psbA and rbcL gene sequences showed that C. cylindrica Okamura was not included in the clade composed of other Cutleria species including the generitype C. multifida (Turner) Greville and the related taxon Zanardinia typus (Nardo) P.C. Silva. Instead, C. cylindrica was sister to the clade composed of the two genera excluding C. cylindrica. Cutleria spp. have heteromophic life histories and their gametophytes are rather diverse in gross morphology, from compressed or cylindrical‐branched to fan‐shaped, whereas the sporophytes are rather similar. In contrast, the monotypic species Z. typus has an isomorphic life history and resembles fan‐shaped Cutleria in morphology. Morphological comparisons of these taxa revealed that C. cylindrica is morphologically distinct from other Cutleria spp. and Z. typus in having cylindrical gametophytes with multiseriate trichothallic filaments instead of uniseriate filaments (hairs) characteristic of Cutleriales (or Cutleriaceae, Tilopteridales), and in lacking rhizoidal filaments in the crustose sporophytes. Therefore, based on the molecular and morphological data, the establishment of a new genus Mutimo to accommodate C. cylindrica, and the new combination of M. cylindricus, is proposed.     

Starch Grain Casts and Moulds in Eocene (Tertiary) Fossil Mangrove Hypocotyls

Further examples of the recently reported fossil starch graincasts and moulds in the fossil mangrove Ceriops cantiensis Chandlerfrom the London Clay (Eocene) of the Isle-of-Sheppey, Kent,England have now been discovered. In addition, similar structureshave been found in the fossil hypocotyls of Palaeobruguieraelongata Chandler from Herne Bay, Kent and also in four recentlycollected hypocotyls of a new species of fossil mangrove fromSheppey. Starch grains from herbarium material of the extantmangrove genera, Bruguiera and Ceriops, have been examined forcomparison with the fossil forms. starch grain casts, fossil, mangrove, hypocotyls, palaeobotany, Eocene, framboids, Rhizophoraceae, Bruguiera sexangula, Ceriops cantiensis, Palaeobruguiera elongata     

Recent and Tertiary Seeds of the Nymphaeaceae sensu lato with a Revision of Brasenia ovula (Brong.) Reid and Chandler

The nine extant genera within the Nymphaeaceae s l (Water Lilies)are shown to be separable from one another on the basis of seedmorphology In particular, epidermal detail, vertical sectionof the testa and relative position of the micropyle and hilumare diagnostic for each genus These features are consideredin connection with current systematic treatments of this familyFossil seeds are reviewed at the generic level and many of theseeds previously assigned to Brasenia ovula (Brong ) Reid andChandler are shown to belong to an extinct genus of Nymphaeaceaeintermediate between the currently accepted families Cabombacaceaeand Nymphaeaceae s s They are redescribed as Sabrenia chandleraegen et sp nov. The British Tertiary fossils Brasenia spinosaChandler, Palaeonymphaea eocenica Chandler emend and ?Nymphaealiminis sp nov are described Fossil material of Carpolithesovulum Brongniart 1822a, Brasenia victoria (Casp ) Weberbauer1893, B teumeri Kirchheimer 1935, B tenuicostata Nikitin 1965and Nymphaea arethusae Grambast 1962 has been studied for comparativepurposes The use of ‘?’ before the extant genericname is advocated when all features of a fossil indicate thatit may be placed in a living genus but when certain additional,critical features of the living genus are lacking on the fossil. Nymphaeaceae, water lilies, seeds, palaeobotany, Tertiary, Sabrenia chandlerae gen et sp nov Nymphaea liminis sp nov, Brasenia ovula     

Developmental Genetics and Morphological Evolution of Flowering Plants, Especially Bladderworts (Utricularia): Fuzzy Arberian Morphology Complements Classical Morphology

This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (1879–1960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (‘FAMmers’)treat structural categories (e.g. ‘roots’, ‘shoots’,‘stems’, ‘leaves’, ‘stipules’)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (‘ClaMmers’) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the ‘leaf’, the FAM Approach is identical toArber's ‘partial-shoot theory of the leaf’ and Sinha's‘leaf shoot continuum model’. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants     

Dessication-induced Changes in the Protein Complement of Soluble Extracts from Leaves of Resurrection Plants and Related Desiccation-sensitive Species

Polyacrylamide gel electrophoresis studies were conducted onthe soluble proteins of angiosperm plants whose leaf protoplasmcan revive from complete dehydration (Xerophyta viscosa, Talbotiaelegans, Sporobolus stapfianus, Myrothamnus flabellifolia, Boryanitida) and of desiccation sensitive plants (Sporobolus pyramidalis,Eragrostis tenuifolia, Selaginella kraussiana). Changes in thesoluble protein composition were found in all species afterdehydration, and were extensive in most species, both resurrectionand non-resurrection. Both groups showed loss of protein bands,but there was no consistent pattern of compositional changewithin either type of plant. Net hydrolysis of high molecularweight protein could be deduced, and the possibility of disulphide-mediatedaggregation arose in some species. Induction of tolerance todesiccation in Borya nitida appeared to be associated with retentionor restoration of the control pattern of protein bands in contrastto loss of very low and very high mol. wt protein (loss wasextreme in desiccation-killed leaves). There was evidence of a disproportionately great synthesis ofvery low mol. wt protein during the midphase of rehydrationin X. viscosa. These results point to the possibility of an important roleof protein synthesis for survival of dehydration. Resurrection plants, desiccation-sensitive plants, protein complement, polyacrylamide gel electrophoresis     

EOCENE ALGAE AND PLANT HAIRS FROM THE GREEN RIVER FORMATION OF WYOMING

Four new species of algae and two kinds of fossil plant hairs are described from a rich oil shale bed of the mid-Eocene Green River Formation of Wyoming. Two of the algae belong to the Cyanophyceae and two to the Chlorophyceae. On the basis of their morphology alone, they are assigned to four new species among four genera, as follows: Symploca hedraia, sp. n.; Stigonema anchistina, sp. n.; Schizochlamys haywellensis, sp. n.; and Spirogyra wyomingia, sp. n. One kind of fossil plant hair is similar to those observed in organic sediments of an existing lake and identified with trichomes on the under surface of live oak leaves (Quercus virginiana). Assignment of the fossil trichomes to a taxon is not warranted at present.     

Ontogeny of the Behavior of Strombus maculatus (Gastropoda: Strombidae)

The ontogeny of strombid behavior was studied by observing thebehavior of Strombus maculatus veligers collected from the planktonand reared past metamorphosis to adults, and by observing juvenilestrombids collected in the field. Complete adult modal actionpatterns (MAP's) associated with locomotion, feeding, and rightingof overturned shells are performed by S. maculatus juvenilesimmediately after metamorphosis. There are changes in the frequencyof the use of certain MAP's which are associated with variationsin shell shape and size. The unique strombid escape response to molluscivorous gastropods(Conns spp.) is not released until juvenile S. maculatus arethree weeks past metamorphosis and two millimeters in shelllength. At that stage, the complete response is released uponthe first encounter with a predator. Experience with a predatordoes not seem to lower the age or size criteria. During ontogeny there is a trend toward an increasing complexityof behavior which is paralleled by an increasing complexityof neural structure and general morphology. There are majorsteps in the ontogeny of strombid behavior which probably coincidewith neural and morphological stages.     

Structure and Development of Stomata on the Vegetative and Floral Organs of Some Amaryllidaceae

The structure and development of stomata in 10 Amaryllidaceousmembers are described. The study is made on the leaves and floralorgans of Amaryllis belladona, Crinum asiaticum, C. bulbispermum,C. latifolium, C. pratense, Pancratium sp., Polianthes tuberosa,and Zephyranthes atamsco, and on leaves of Agave sp. and Curculigoorchioides. In most of the organs of the different plants studiedmore than one type of stoma occur, even on the same surface.However, the stomata are largely anomocytic in Amaryllis, Crinum,Pancratium, Polianthes, and Zephyranthes, but they are tetracyticin Agave and Curculigo. An increase in the number of subsidiarycells in teracytic, tricytic, paracytic, and stomata with onesubsidiary cell has been noted. It may be due to wall formationin the subsidiary cells or by the neighbouring perigenes assumingtheir form. The range of variation in different types of stomatain each organ has been studied. Abnormal features such as juxtaposedor superimposed contiguous stomata, connections between guardcells of nearby stomata, transformation of meristemoids intoepidermal cells are observed. The development of different typesof stomata in different organs of the same plant is perigenous.The systematic position of different genera is discussed inlight of the present findings. A method of preparing epidermalimprints by the use of Depex, a mounting medium, and white ofan egg is also described.     

The Fossil Record of the Epacridaceae

Fossil pollen and macrofossils of Epacridaceae are uncommonand are mainly known from Tasmania and other parts of south-easternAustralia. Most epacrids have generalized ericalean pollen althoughthe pollen of some genera is distinctive. Ericalean pollen isknown from the late Cretaceous. The first occurrence ofParipollisorchesis pollen, which is consistent with some extantEpacrisspecies,probably means that Epacridaceae, and possibly the tribe Epacrideae,had differentiated by the Middle Eocene. The fossil record at present provides minimum ages of the firstoccurrences of major subfamilial taxa. Macrofossils of subfamilyRicheoideae and of several morphotypes of the tribe Epacrideaeare known from the Early Oligocene. Tribe Cosmelieae pollenand macrofossils are known from the Early Pleistocene, and areprobablySprengelia. The oldest Australasian fossils of tribeStyphelieae are leaves in latest Oligocene–Early Mioceneparts of the Latrobe Valley coal. Endocarps identified as Epacridaceaefrom the Eocene of England need further investigation. PollenofMonotoca, or a close relative, is known from the mid-Miocene.PossibleTrochocarpaleaves occur in Late Oligocene/Early Miocenesediments, and fossil leaves indistinguishable from the extantTasmanian rainforest species,T. gunniiandT. cunninghamii, areknown from the Early Pleistocene in Tasmania. Epacridaceae; macrofossils; microfossils; Cretaceous; Cainozoic     

ANGIOSPERM PALEOBIOCHEMISTRY OF THE SUCCOR CREEK FLORA (MIOCENE) OREGON,USA

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.     

Earliest ontogeny of Early Palaeozoic Craniiformea: implications for brachiopod phylogeny

Popov, L.E., Bassett, M.G., Holmer, L.E., Skovsted, C.B. & Zuykov, M.A. 2010: Earliest ontogeny of Early Palaeozoic Craniiformea: implications for brachiopod phylogeny. Lethaia, Vol. 43, pp. 323–333. Well preserved specimens of the Early Palaeozoic craniiform brachiopods Orthisocrania and Craniops retain clear evidence of a lecithotrophic larval stage, indicating the loss of planktotrophy early in their phylogeny. The size of the earliest mineralized dorsal shell was <100 μm across, and the well preserved shell structure in these fossil craniiforms allows their earliest ontogeny to be compared directly with that of living Novocrania, in which the first mineralized dorsal shell (metamorphic shell) is secreted only after settlement of the lecithotrophic larvae. Immediately outside this earliest shell (early post‐metamorphic or brephic shell) and in the rest of the dorsal valve the primary layer in both fossil and living craniiforms has characteristic radially arranged laths, which are invariably lacking in the earliest dorsal shell. The ventral valve of the fossil specimens commonly preserves traces of an early attachment scar (cicatrix), which is equal in size to the dorsal metamorphic shell, and the brephic post‐metamorphic ventral valve also has a primary shell with radially arranged laths. However, a primary shell with radial laths is completely lacking in the ventral valve of living Novocrania, indicating that heterochrony may have been involved in the origin of the encrusting mode of life in living craniids; the entire ventral valve of Recent craniids (with the possible exception of Neoancistrocrania) may correspond to the earliest attachment scar of some fossil taxa such as Orthisocrania. It is also probable that the unique absence of an inner mantle lobe as well as the absence of lobate cells in Novocrania could be the result of heterochronic changes. The dorsal valve of both fossil and living craniiforms has a marked outer growth ring, around 500 μm across, marking the transition to the adult, and a significant change in regime of shell secretion. The earliest craniiform attachment is considered to be homologous to the unique attachment structures described recently in polytoechioids (e.g. Antigonambonites) and other members of the strophomenate clade. However, unlike the craniiforms, polytoechioids and strophomenates all have planktotrophic larvae, and planktotrophy is most probably a plesiomorphic character for all Brachiopoda. □Brachiopoda, Craniiformea, Early Palaeozoic, ontogeny, phylogeny.     

Arrangement of Stomata on the Leaves of Pelargonium zonale and Sedum stahlii

Stomata of Pelargonium zonale are orderly arranged on the surfaceof the lower epidermis. Inter-stomatal and Inter-trichome distancesas well as the number of sides of stomata, epidermal cells adjacentto stomata, and regular cells of the epidermis have characteristicprobability distributions. A model of epidermal developmentis constructed based upon the quantitative features of eachtype of cell. The primary restriction of the model is that stomainitials inhibit adjacent cells from becoming stoma initials. A second type of stomatal arrangement occurs in Sedum stahliiand an appropriate model for the ontogeny of epidermal cellsin this plant can also be constructed that has similar quantitativecharacteristics to those of real fields of cells. The applicationof modelling in plant morphology is discussed with respect tounderstanding ontogeny and phylogenic relationships.     

Labyrinth morphology and the evolution of low-frequency phonoreception in elasmobranchs

Labyrinth morphology in extant elasmobranchs (neoselachians: sharks, skates and rays) and several extinct chondrichthyans ranging in age from Pliocene to Devonian is investigated using high-resolution computed tomography (CT scanning) and digital reconstitution techniques. The elasmobranch labyrinth is highly specialized toward low-frequency semi-directional sound detection (LFSDP), optimally around 100 Hz. Several features associated with LFSDP in neoselachians also occur in Mesozoic hybodonts (e.g., Egertonodus, Tribodus) and in some incertae sedis extinct sharks (Acronemus, Tristychius), but are absent in osteichthyans, extant and fossil holocephalans, and certain Paleozoic chondrichthyans (ctenacanths, symmoriiforms, Pucapampella). Thus, LFSDP is regarded as an evolutionary novelty of elasmobranchs that arose some time after their divergence from chimaeroids. The suite of characters associated with LFSDP was probably acquired progressively, some characters being more widely distributed among fossil chondrichthyans than others. LFSDP evolved only within chondrichthyans whose otico-occipital fissure became secondarily closed during ontogeny.     

The Pattern of Respiration Rate in the Vegetative Barley Plant

In two experiments with young barley plants, respiration rate,carbohydrate content and growth rate of the whole plant weremeasured. When 18-day-old plants were darkened the rate of respirationand the levels of soluble carbohydrate fell in parallel overthe following 30 h. When the dark respiration rate of plantswas followed from 7 to 24 days respiration rate and solublecarbohydrate levels did not change together, nor did the respirationrate (R) follow the empirical relationship with photosynthesis(P) and d. wt (W) R = aW + bP, suggested by McCree. Hordeum distichum L. (Lam), barley, respiration, carbohydrate content