Abstract: Silicified layers of plant material from the Late Permian Blackwater Group of the Bowen Basin, Queensland, contain seed-bearing organs associated with Glossopteris leaves; comparison of these organs with attached fertile glossopterid structures previously described from compressions indicates the petrified organs are undoubtedly of Glossopteris. The fructification consists of an infolded megasporophyll with loosely overlapping lateral margins forming an envelope bearing sessile gymnospermous seeds on the inner surface. The seeds contain a megagametophyte with one archegonium. Previous interpretations of fertile glossopterid structures as cupular valves, fertiligers, and cones with a subtending bract, e.g. Dictyopteridium and Scutum, are now reinterpreted as having a similar arrangement of megasporophyll envelope (= subtending bract of ‘cone’) enclosing the seeds. Pollen-bearing organs in the deposit are of the Arberiella type and contain bisaccate pollen. Similar pollen grains are found in the micropyles ...

Abstract: For the period ca. 15 000-10 000 years ago, which spans the interval between the latest presence of lowland ice and the final disappearance of mountain glaciers from Britain, so many botanical data are now available that it is possible to analyse plant distributions and vegetation composition in detail not yet possible for earlier periods. Species lists, provided by identification of pollen and of macroscopic remains, show a combination of diverse phytogeographic elements into an assemblage characteristic of the period - an admixture of apparently thermophilous plants with those now found in northern and arctic situations, and of oceanic and steppe elements. Ordination of data on floras has revealed much similarity between the regions of Britain, but pollen analysis continues to emphasize how strong must have been the regional differentiation of vegetation. A comparison of pollen diagrams published since 1970, from sites lying on a broad north-south transect of western Britain, shows much variety in the pollen assemblage zones which have been distinguished, and in the vegetation interpreted from the pollen data by comparison with surface samples and modern vegetation. Sufficient $^{14}$ C dating is now available, however, to permit chronostratigraphic correlation of these pollen zones, and to show that there is consistent evidence for climatic amelioration at about 13 000 B.P., and rapid deterioration at about 11 000 B.P., leading to conditions of incomplete vegetation cover and universal soil disturbance which can be correlated with geomorphological evidence for the recrudescence of mountain glaciation in western Scotland, the Lake District, and North Wales, in the period called Younger Dryas on the continental mainland. Between 13 000 and 11 000 there is in western Britain evidence for a woodland biozone, or palaeobotanical interstadial, equivalent to Bolling plus Allerod of continental stratigraphers (Mangerud, Andersen, Berglund & Donner 1974), and divided by a very minor regression of vegetation during Older Dryas time (ca. 12 000-11 800). The now closely $^{14}$ C-dated site at Low Wray Bay, Windermere, is described in detail, and suggested as a reference site for this interstadial.

Abstract: Seven species of phytoseiid mites were collected from citrus trees in the Mediterranean region during a survey in 1971.Amblyseius stipulatusAthias-Henriot was the most abundant and widespread species in all countries surveyed (Turkey, Greece, Italy, Spain).A. californicus (McGregor) was collected only in Spain;A. potentillae (Garman) andPhytoseiulus persimilis. A.-H. only in Italy.Typhlodromus talbii A.-H. was collected in Greece and Spain,T. athiasaePorath & Swirski in Greece and Turkey, andIphiseius degenerans (Berl.) in Greece and Italy. Living material of all species exceptT. talbii was successfully shipped to California and insectary cultures established. Biologies were studied in the laboratory under 2 food regimes:Tetranychus pacificusMcGregor eggs and larvae, and pollen ofMalephora crocea (Jacq.). Pollen was not a satisfactory food forp. persimilis, A. californicus andT. athiasae. Pollen was slightly less satisfactory than tetranychid mites fora. potentillae, but was equally or more favorable than mites forA. stipulatus andI. degenerans. A. stipulatus has become established in southern California.

Abstract: We present evidence that birds pollinate many native plants. Honeyeaters persistently and often visit flowers and regularly cany pollen. When they probe another flower some pollen is deposited on the stigma, thus effecting pollination. Floral structure or the arrangement of inflorescences ensures that birds probing flowers will regularly brush the anthers and stigmas. The pollen is carried on the bdl or feathers and is well suited to its mode of transport. No specific relation between birds and flowers was found. Each species of bird visited many flowers and each species of plant was visited by many species of birds. The plants appear adapted to the Meliphagidae as a whole. However, insects also visited many plants. The importance of birds compared to insects as pollinators is discussed.

Abstract: When seed production following selfand cross-pollination is similar, a species is usually regarded as self-compatible. On this basis, Ray and Chisaki (1957a) reported that the distylous species of Amsinckia (Boraginaceae) are either fully or partly self-fertile. The combination of floral heteromorphism and self-compatibility is unusual, since most heteromorphic species that have been studied are selfincompatible (Vuilleumier, 1967). Recent pollen flow studies of Amsinckia grandiflora Kleeb. indicate that pollinations of this species include a large proportion of intramorph pollination (Ornduff, 1976). However, in two out of three years, samples in a population revealed that the two morphs occurred in equal numbers, which in a selfcompatible distylous species would suggest a high rate of outcrossing. These observations led us to investigate the possibility that this species possesses a cryptic incompatibility system. This possibility was investigated by studies of progeny resulting from natural and artificial pollinations, pollen competition studies, and pollen tube growth studies.

Abstract: Morphologic changes occurring during pollen grain activation and ultrastructural features of Lycopersicum peruvianum Mill. pollen tube during the first stages of growth in vitro have been studied. The more evident morphologic changes during activation, in comparison to those already described for mature inactive pollen, concern dictyosomes, rough endoplasmic reticulum (RER), and ribosomes. The dictyosomes are very abundant and produce “large” and “small” vesicles. Near the germinative pores both types of vesicles are present, while all along the remaining cell wall only the large type is observed. These latter react weakly to Thiery's test and probably contain a callose precursor necessary for the deposition of a callosic layer lining at first only the inner side of the functioning pore and occasionally the other two pores, and subsequently the entire inner surface of the cell wall. The small vesicles, highly positive to Thiery's test, are present only near the pores and could be involved in the formation of the pectocellulosic layer of the tube wall. The setting free of RER cisterns, which in the mature inactive pollen were aggregated in stacks, coinciding with polysome formation and resumption of protein synthesis, is in accord with the hypothesized role of RER cistern stacks as a reserve of synthesizing machinery. The pollen tube reaches a definitive spatial arrangement soon after the generative cell and vegetative nucleus have moved into it. At this stage four different zones that reflect a functional specialization are present. In the apical and subapical zone two types of dictysosome-originated vesicles, similar to those found in the activated pollen grain, are present. Their role in the formation of the callosic and pectocellulosic wall layers seems to be the same as in the activated pollen grain.

Abstract: New discoveries of fossil pollen of Pelliceria in Tertiary deposits of the Caribbean extend both the stratigraphic and geographic range of the genus in the Antilles and Central America. The new records include specimens from the Eocene of Jamaica, Eocene of Panama, and Oligo-Miocene of Panama. Factors suggested for explaining the range restriction of Pelliceria, from once widespread throughout the Caribbean, to presently from Pacific Costa Rica to northwestern Colombia, include sea-level fluctuations, climatic trends toward cooler conditions, and competition from extensive communities of Rhizophora which first developed in the Caribbean region during the Oligocene. THE GENUS Pelliceria' is a monotypic member of the Theaceae (Pelliceriaceae fide Airy Shaw 1966) presently restricted to lowland coastal areas from Puntarenas in Costa Rica, through Panama and northwestern Colombia, to the Esmeraldas Province of Ecuador (Holdridge, pers. comm. 1976). The single species, P. rhizophorae Planchon and Triana (the 'palo de sal' in Panama), is a mangrove but lacks the characteristic prop-roots (cf. Kobuski, 1951: 258). It frequently occupies sites where rivers empty into the Pacific (Genuty, pers. comm. 1976), or slightly brackish water zones behind the mesoto euryhaline strand of Rhizophora-Laguncularia-Avicennia. In the mangrove region of the Osa Peninsula of Costa Rica, however, it is associated with Rhizophora in areas of highest salinity. At Main Beach and Playa Grande, Panama, "It develops best along the main drainage channels of the swamp in constantly wet soils that are very shallowly inundated at high tide, usually in company with Rhizophora and Laguncularia" (Johnston 1949: 207). Pelliceria is a small tree, usually between 5-10 m in height but occasionally reaching 20 m. In the Golfo Duke region it has . . . "a very straight, unbranched trunk and narrow crown. The trees have a very strongly developed, deeply fluted pyramidal buttress at the base, even in young specimens, and are unique in this character in the mangrove association" (Allen 1956: 287). Kobuski (1951) and Cuatrecasas (1958) provide further taxonomic and ecological information on the genus. In 1964 van der Hammen and Wijmstra described a fossil pollen type, Psilatricolporites crassus, from the Tertiary of the Guiana Basin. Subsequently Langenheim et al (1967) reported "Pelliciera-type pollen" from the Oligo-Miocene Simojovel Group of Chiapas, Mexico (plate XLII: 315). Wijmstra (1968) recognized the Chiapas specimens as similar to Psilatricolporites, and the biological affinities of the latter were established. Later pollen of Pelliceria was also described from the Oligocene of Puerto Rico (Graham and Jarzen 1969, figs 66-68). Germeraad et al. ( 1968) summarize its stratigraphic range in the Caribbean as basal Eocene to Recent. Thus with the recognition of fossil pollen of P. ctasus as belonging to Pelliceria, the latter, presently restricted to Pacific Central and northern South America, is revealed as a once widely distributed mangrove extending from northern South America to south-central Mexico and the Antilles (fig. 1). Recently, new occurrences of Pelliceria have been discovered in the Caribbean Tertiary establishing the genus as even more abundant and widespread. The pollen of Pelliceria is variable both in size and ornamentation. Some specimens have conspicuous mound-like scabrae with a fine sub-reticulum evident at lower focal levels (fig. 2A insert, fig. 2B). In others the scabrae are less conspicuous, and the grains are distinctly reticulate (e.g., figs. 2G, H). Size ranges from ca. 40,u to 90u in modern pollen, with moderate percentages of smaller abortative grains present in some preparations. Germeraad et al. (1968) noted these variations and suggested they may represent various states of preservation (viz., erosion of the scabrae). However, comparable range in size and ornamentation is also evident on modern reference slides prepared from a single flower. The pollen of Pelliceria is distinct, and similar ranges in size and ornamentation are present in both modern pollen and fossil specimens from the Caribbean.

Abstract: SUMMARY The number of cross-pollen tubes in the styles of self-incompatible kale plants was reduced by 46–94% when self-pollen was applied to the stigma immediately before the cross-pollen. Similar reductions were found when the cross-pollen was applied at time intervals of 2–16 h after the self-pollen, but little or no reduction occurred when the time interval was 24 h or 32 h. No reductions were found when cross-pollen was applied before self-pollen nor when dead cross-pollen was applied before the live cross-pollen. Application of onion pollen before cross-pollen gave a mean reduction of 69%. The results are discussed in the context of current views on the mechanism of self-incompatibility in Brassica, and their practical implications for the breeding of F1 hybrid brassicas.

Abstract: Flower buds, anthers, and/or pollen grains collected at the time of first haploid mitosis and 1-2 d before or after this division were submitted to different treatments before culturing anthers or isolated pollen grains. In the case of anther culture, the percentages of androgenic anthers were noted at the end of 2, 3, 4, and 5 weeks of culture. Statistical studies of the results thus obtained showed that some factors were highly effective in favouring androgenesis. The best results were obtained 1-2 d after the first haploid mitosis with anthers centrifuged at 40 g for 5 min after cold treatment of the flower buds (48 h at 3 °C) ; these treatments increased the percentage of androgenic pollen grains 12-fold. In case of isolated pollen grains, a system of culture particularly favourable for induction and development of androgenic embryos was found. This system included a cold treatment of the flower buds (48 h at 3 °C), the centrifuga tion of the isolated pollen grains (120 g for 15 min), and culturing them for 20 d in the dark and then in continuous light.

Abstract: The vegetation of the area east of the Klutlan Glacier in the St. Elias Mountains is described with the methods of European phytosociology. Four major vegetation types are recognized: Picea glauca forests, Populus balsamifera forests, Betula glandulosa shrub–tundra, and Dryas integrifolia tundra.The modern pollen assemblages deposited in these vegetation types are determined by pollen analysis of surface moss polsters, lake muds, and moss samples from sedge swamps. Numerical analyses of the surface spectra indicate that spectra from the Dryas tundra and from the Populus forests are distinctive in their pollen composition. The variation in the percentage pollen content of samples from the Picea forests and the shrub–tundra is so great, even when spectra from a single sample type are considered, that no reliable distinctions can be made in modern pollen spectra from these two community types.

Abstract: A B S T R A C T External pollen morphology of 39 species of West Indian Vernonias was examined by light and scanning electron microscopy in conjunction with a systematic revision of these species. There were three distinct types of pollen: Type A: subechinolophate, tricolporate grains with prominent spines; Type B: echinolophate, tricolporate with expanded germinal furrows and coincident polar muri; Type C: echinolophate, tricolporate grains with prominent polar lacunae. Pollen grains intermediate between the major types were found in several species. These same species had very distinct and atypical megamorphologies. In general, pollen types were found to correlate well with classification based on megamorphological characters, particularly at the infrageneric level, and to provide confirmation of subsectional assignments in the genus. VERNONIA (Compositae) is a large and predominately tropical genus with over 500 species in the New World, 40 of which occur in the West Indies. The West Indian Vernonias have similarly appearing flower heads and inflorescences, but show great diversity in vegetative features such as leaf shape, pubescence, and growth habit. These floral and vegetative characters which have formed the basis for taxonomic boundaries among species show much intraspecific variability. This variability has led to disagreement in previous taxonomic treatments which have conflicted at the specific and infrageneric levels (Gleason, 1906, 1922; Ekman, 1914). Species relationships have consequently become obscured, making it difficult to construct a workable taxonomy and to arrange phylogenetic groupings. In light of this confusion additional previously unexamined characters are needed. The work of Wodehouse (1928), Erdtman (1966), and others indicated that pollen morphology can provide useful taxonomic characters if the surface morphology is sufficiently dis

Abstract: The seed set of eight bog plants in the Ericaceae family was reduced by excluding insect flower visitors even though hand-pollination tests showed that all eight species were self-compatible. Floral morphology evidently minimizes the possibility that pollen will be transferred from anther to stigma in the absence of insect visitation. Bees were the most important flower visitors, collecting nectar and (or) pollen. The attractiveness (nectar and (or) pollen extractable per minute) of the ericad flowers varied considerably. This variability would promote forager specialization and flowering-timing diversification if the ratio of insect visitors to flowers was low.

Abstract: The role of hawkmoths as pollen dispersers is poorly understood; a recent review by Levin and Kerster (1974) does not cite a single study of dispersal by these pollinators. This report deals with a brief study of pollen dispersal in the tropical shrub Lindenia rivalis Benth. (Rubiaceae) which usually grows in scattered linear populations along streams. The work was done on 18-20 June 1973 in the Columbia Forest (Toledo District), Belize.

Abstract: Rice (Oryza sativa L, 2n=24) anthers containing microspores in the early-uninucleate to first-mitosis stages were induced successfully to develop into plants in vitro through an intermediary step of callus formation Callus initiation occurred with highest frequency in anthers containing mid-uninucleate imcrospores The callus derived from different stages of microspore development differed in the potential to differentiate into plants The plants regenerated from pollen callus were predominantly haploid or diploid; polyploid and aneuploid plants were relatively infrequent The first division of the uninucleate microspores was asymmetrical, resulting in the formation of large vegetative and small generative nuclei The vegetative nucleus divided repeatedly and assumed the major role in the formation of callus, whereas the generative nucleus degenerated rapidly Simultaneous division of the two nuclei was observed in a few pollen grains Nuclear fusion during the very initial stages of pollen development was postulated to account for the occurrence of the diploid and polyploid plants

Abstract: The volume of hydrated pollen grains of Petunia hybrida L during swelling in germination medium increased three times The volume of desiccated pollen grains increased only two times after transfer to the same medium This difference in swelling ability is attributed to different rigidities of the pollen grain wall,ccaused by the different hydration states The relationship between pollen grain swelling and germination metabolism with regard to relative humidity is discussed

Abstract: SUMMARY Populations of Pontederia rotundifolia in the Lower Amazon and Costa Rica are tristylous. A strong pollen trimorphism is associated with differences in stamen and style length in the three floral forms. The results of a controlled pollination programme with thirty individual plants of P. rotundifolia demonstrate that floral trimorphism is accompanied by a physiological self-incompatibility system typical of many heterostylous plants. Legitimate pollinations are considerably more productive of seed than illegitimate pollinations. Individual plants exhibit differences in the strength of self-incompatibility, but in general, short-styled plants possess the strongest self-incompatibility, long-styled plants are intermediate and mid-styled plants have the weakest self-incompatibility. Large differences in the strength of self-incompatibility are expressed in self-pollinations with pollen from the two anther levels of each style form. Natural populations of P. rotundifolia often contain only a single style form or contain unequal proportions of style forms. Seed set, resulting from moderate self-compatibility, occurred in a Cosra Rican population that contained only short-styled plants. Two populations associated with rice cultivation in the Lower Amazon contained equal proportions of the three style forms. The seed set of the three forms within these populations was similar. The floral trimorphism and breeding system of P. rotundifolia are compared with those of the related P. cordata and Eichhornia crassipes.

Abstract: For the establishment of floristic sequences, pollen and spore fioras from the Late Cretaceous sediments ranging from Cenomanian to Maestrichtian of northern Japan are studied. Four areas where the Late Cretaceous sediments are typically weli developed are selected: the Ishilcari coal field (the Campanian-Maestrichtian Hakobuchi Group), Saku area (the Cenomanian-Campanian Middle and Upper Yezo Groups), the Kuji goal field (the early Senonian Kuji Group) and the 3oban coal field (the early Senonian Futaba Group). Nine pollen and spore fioras two of which had been studied by previous investigators, are discussed. Based on fioristic composition and components, the four floras of CenomanianTuronian, Early Senonian, Campanian and Maestrichtian ages are distinguishable. The oldest fiora is characterized by diverse pteridophytes, particularly Schizaeaceous spores, and by less diversified angiosperms containing few porate pollen. The second has still the relic of Mesophytic appearance: pteridophytes are more or less superior to angiosperms in taxonomic diversity, containing commonly Schizaeaceou's and Gleicheniaceous spores. Of gymnosperm pollen Cycadopites, Monosulcites, Araucariacites, Rugubivesiculites and Classopollis are common. Angiosperm are composed predominantly of tricolpate pollen, but are represented by few porate pollen. The third is characterized by the predomint angiosperms and also by diverse species of Aquilapollenites. Pteridophytes are sparsely represented in Schizaeaceous spores. The youngest flora is composed of a predominant porate pollen, which occupies a majority of angiosperm pollen. This flora is characterized also by diverse pollen of uncertain taxonomic position such as Aquilapollenites, "iodehouseia and Ocellipollis. These fioristic sequences in northern Japan shows thqt pteridophytes and gymnosperms forming the major constituents during Cenomanian-Turonian times were gradually replaced by angiosperms towards Maestrichtian time. Late Cretaceeus floristic changes of northern Japan are very similar to those of Eastern Siberia, especialiy of the Zeya-Bureya basin.