Carex yandangshanica sp. nov. (Cyperaceae; C. sect. Rhomboidales) from Zhejiang,China

Carex yandangshanica C. Z. Zheng & X. F. Jin, a new species of Carex sect. Rhomboidales Kükenth. from Zhejiang, China, is described and illustrated. The new species is similar to C. thibetica Franch. and C. brevicuspis C. B. Clarke, but differs from the former by having trabeculate leaves, pistillate spikes with 6–10 staminate flowers or without staminate flower at the apex, and achenes at apex contracted into a slightly curved beak, and from the latter by having lateral culms, trabeculate leaves, and elliptic, rubiginous and awned pistillate scales. SEM microphotographs of perigynia and achenes are provided for the new species and related taxa.     

Floral ontogeny of <Emphasis Type="Italic">Schisandra chinensis</Emphasis> (Schisandraceae): implications for androecial evolution within <Emphasis Type="Italic">Schisandra</Emphasis> and <Emphasis Type="Italic">Kadsura</Emphasis>

The organogenesis of staminate and carpellate flowers of Schisandra chinensis (Schisandraceae) was investigated with scanning electron microscopy, with observations on the development of tepals reported for the first time. The results showed that there is no interval between the initiation of the last tepal and that of the first stamen or carpel, and that the shapes of tepal, stamen, and carpel primordia are similar. The tepals and stamens of staminate flowers are initiated acropetally in a continuous spiral Fibonacci phyllotaxis, with no carpel structures observed; the filaments are not connate. The organogenesis of the carpellate flowers is similar to that of the staminate flowers, but with no evidence of stamen development. The carpels are ascidiate without postgenital fusion. Three androecial characters of Schisandra and Kadsura are discussed in a phylogenetic context. The subglobose or obovoid androecium of Schisandra propinqua and Schisandra plena may be homologous with that in sections Kadsura and Sarcocarpon. The plesiomorphic form of the androecium within the two genera is likely to be elongate with more than ten free stamens.     

Histological and Morphological Studies of Pollen Grains from Elongata, Reduced Elongata and Staminate Flowers in Carica papaya L.

The quality and quantity of pollen from three types of flowers; elongata, reduced elongata and staminate from the commercialized Thai papaya cultivar ‘Khak Nual’ were determined using pollen morphology, pollen physical characters and pollen development processes. Pollen development progressed at the same pace in the three types of pollen-producing flowers and was consistent with pollen development in many angiosperms. Pollen morphology showed that papaya pollen grains are tricolporate, with three apertures, and there is no significant difference in diameter (25.18–25.72 μm) and weight (11.76–15.45 ng) among pollen sources. The staminate flower shows the lowest amount of pollen, with 12,368 pollen per anther, but higher viability and germination rates of 95.53 % and 53.64 %, respectively. In contrast, the elongata type shows the highest amount of pollen grains with 14,884 pollen per anther and the lowest viability and germination rates, 93.06 % and 46.33 % respectively. The physical characteristics of pollen grains from reduced elongate and elongate flowers are similar. Reduced elongate flower type can donate pollen without self-pollinating.     

Monograph of Carex section Schiedeanae (Cyperaceae): Unexpected taxonomic and ecological diversity in a Mexican sedge clade

Carex section Schiedeanae (subg. Euthyceras) has long been thought to comprise at most five species of Mexican sedges. Our morphological studies in the field and herbarium, however, supported by more recent DNA sequencing work, demonstrate that the section is, in fact, three times as species-rich, making it one of the largest sections in Mexico. Its 15 species range from Chihuahua to Tamaulipas south to Veracruz and Oaxaca; a single species, Carex muriculata, extends into the United States. The section has unusual inflorescences with simple (except in Carex complexa), uniformly androgynous, sessile spikes, utriculiform cladoprophylls, and perigynia with a unique combination of pubescence types composed of papillae; unicellular, simple hairs; and (in many species) multicellular tubercles. We recognize five previously described species (C. muriculata,Carex perstricta,Carex schiedeana, Carex stellata, and Carex vizarronensis) and describe 10 additional species (Carex angustilepis, Carex cabralii, Carex complexa, Carex dentata, Carex gypsophila, Carex mesophila, Carex paneroi, Carex planilamina, Carex revoluta, and Carex tehuacana). We have expanded the morphological features used in the section to include particularly anther, staminate scale, and style features, and more detailed micromorphology of the perigynia, especially indumentum. In total, 13 of the 15 species recognized herein, with a total of 32 individuals, were examined for ETS and ITS for phylogenetic reconstruction. Phylogenetically, the xeric species (plus C. paneroi) form a grade leading to a clade of the more mesophytic species adapted to forest understories, plus the unique cliff dwelling C. complexa.     

Observations of inflorescence patterns and flower sex in a population of Sagittaria papillosa Buch. (Alismataceae)

Sagittaria papillosa Buch. is monoecious with unisexual flowers, pistillate below, staminate above, typically with an unbranched scape. A large population with unusual numbers of staminate and bisexual flowers on the lowest whorl of the inflorescence and many particles was quantitatively evaluated. First-formed inflorescences had more staminate and bisexual flowers than those produced later. Branched scapes were predominantly found to be the second inflorescence produced by a given plant. Genetic crosses between flowers on recemes and panicles produced no branched inflorescences. When grown under greenhouse conditions all tested plants had racemes with pistillate flowers in the lower whorls and staminate ones above. Data from soil parameters, daylengths and air temperatures are compared to reported information on modification of flower sexuality by these factors.     

INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: A CATKIN WITH JUGLANDACEOUS AFFINITIES

Three specimens of one type of fossil catkin from the Middle Eocene of Tennessee are excellently preserved and have been investigated morphologically. The flowers on these catkins are subtended by elongate, three-lobed bracts, are exclusively staminate, and have three conspicuous, obovate, perianth parts that bear large peltate scales. The stamens are well preserved and contain triporate pollen grains that are equivalent to the dispersed pollen genus Momipites. Floral morphology, cuticular features, and pollen indicate close affinities with the extant genera Engelhardia, Oreomunnea, and Alfaroa of the Juglandaceae; but because the fossil catkins are distinct and are a dispersed plant organ, they are placed in a new form genus: Eokachyra. These fossil flowers represent a rare opportunity to correlate the micro- and macrofossil record and to compare the relative rates of evolution of these features. The fossil catkins also demonstrate that much structural information may be gained from the study of fossil angiosperm flowers. The similarities between the staminate flowers of the fossil catkins and the staminate flowers of Engelhardia, Oreomunnea, and Alfaroa confirm the idea that this complex has had a long evolutionary history and suggest that the pollination system of certain extant genera was well developed during Middle Eocene times.     

A new species of <Emphasis Type="Italic">Dioscorea</Emphasis> (Dioscoreaceae) from Central Cuba

Dioscorea pseudocleistogama from the Guamuhaya Massif in central Cuba is described and illustrated. The species is assigned to Dioscorea section Rajania. It can be distinguished from other species of section Rajania by its staminate inflorescences possessing racemes of sessile to subsessile cymes bearing narrowly-tubular staminate flowers with strongly imbricate ligulate tepals, and pollen with the exine rugulate.     

Effects of permanent flooding on Carex-Equisetum wetlands in Northern Sweden

The effect of flooding sites of former, periodically flooded water-meadows in northern Sweden was studied in two areas for two and three years, respectively. The vegetation consisted m mainly of Equisetum fluviatile L., Carex rostrata Stokes, Carex aquatilis Wahlenb., Comarum palustre L., and Lysimachia thyrsiflora L. Increase in water depth caused a significant decrease in the species number. Carex rostrata, C. aquatilis and Lysimachia thyrsiflora were almost eliminated (although Carex aquatilis seemed to be somewhat more tolerant to the increased water depth). Equisetum fluviatile was unaffected, except for increase in shoot length, while the effect of flooding on Comarum palustre was intermediate.The practical application of flooding is discussed with regard to habitat management for waterfowl.     

Variability of perigynium morphology of Central European members of Carex sect. Phaestoglochin (Cyperaceae) from variable plant communities

The number and range of taxa belonging to the Central European section Phaestoglochin (Carex L.) differ significantly among systematic classifications. Our study revealed that all of the quantitative morphological features of perigynia of Carex spicata Huds., Carex muricata subsp. muricata L., Carex muricata subsp. lamprocarpa ?elak., Carex divulsa subsp. divulsa Stokes, and Carex divulsa subsp. leersii Koch., had statistically significant differences among taxa. However, this differentiation did not reflect the known taxonomic divisions of the group and therefore, it did not represent a determining criterion for distinguishing the particular taxa. It also did not confirm the close and significant connections between subspecies within the species studied. Based on morphological features of perigynia, we showed that C. divulsa is a well-distinguished taxon, while the other taxa form a complex group. Analysis of the differentiation of perigynium features among the taxa studied against the background of the plant communities where the plants were grown indicated a distinct effect of the habitat conditions on the morphological features of perigynia.     

Pollination ecology of Magnolia ovata may explain the overall large flower size of the genus

Flowering and fruiting biology of Magnolia ovata was studied in Atlantic forests in the interior of São Paulo State, Brazil. The large, bisexual flowers are protogynous, nocturnal, thermogenic and emit a strong scent in two consecutive evenings. In the first night of anthesis, the flowers are in the pistillate stage and thermogenesis starts at about sunset and lasts about 3 h. In the second night, the flowers enter the staminate stage and produce heat for 4 h. Heat is generated by the petals, gynoecium and anthers. Temperatures measured inside the petals reach 26.7 °C and 31.9 °C in the pistillate and staminate stages, 6.0 and 10.6 °C above ambient air, respectively. In the pistillate stage, the perianth opens after sunset and closes tightly a few hours later, and remains closed until the next evening. The initial opening and closing, however, is not synchronous for all flowers during the night. In the following evening, flowers in the staminate stage again open and remain so until the petals drop. Scent compounds, analyzed by GC–MS, contain C5-branched chain compounds, aliphatics, benzenoids and monoterpenoids. Emission of the most prominent compound, C5-branched methyl 2-methyl butyrate, commences before flower opening and continues throughout anthesis, but is accentuated in the thermogenic pistillate and staminate stages. Female and male individuals of only one beetle species, the dynastid scarab Cyclocephala literata, are attracted to the scented flowers in both pistillate and staminate stages. Once inside the flowers they feed on the petals and mate. Tests with synthetic methyl 2-methyl butyrate indicate that this compound is a strong attractant for the beetles. Because this scent compound is strongly emitted in both pistillate and staminate stages, the beetles fly indiscriminately between flowers of both stages. This behavior enhances pollen mixing and effective cross-pollination of the self-compatible species. The evolutionary history of Magnolia appears to be influenced by an ancestral condition of dynastid scarab beetle pollination. Large magnolia flowers are best explained as an archaic structure resulting from the initial association of tropical American species of section Talauma with large and voracious dynastid beetles.     

An experimental study of the interaction between the dwarf palm (Chamaerops humilis) and its floral visitor Derelomus chamaeropsis throughout the life cycle of the weevil

Palm pollination can be quite diverse but has been poorly studied. This paper describes the life cycle of Derelomus chamaeropsis, a Coleoptera that inhabits the inflorescences of the Mediterranean dwarf palm Chamaerops humilis. D. chamaeropsis is specific to Chamaerops inflorescences, where it eats pollen and the rachis of inflorescences on pistillate plants. They usually lay eggs only on staminate inflorescences where larvae develop and bore into the inflorescence rachis. Larvae do not develop on pistillate inflorescences, except for cases with almost no fruit development. Pistillate plants can thus protect themselves from weevil predation. When visiting pistillate inflorescences, weevils can feed on rachis but usually do not find the brood place reward. Pollination is thus by deceit and weevils should be selected to avoid pistillate inflorescences. D. chamaeropsis pupate within the rachis of staminate inflorescences, but disperse before collecting pollen, thus staminate plants do not have an individual advantage in breeding weevils. However, because larvae develop on dead tissues, the costs of larval development are likely to be low for the plant. This study provides a new example of pollination symbiosis where the pollinator develops on the plant it pollinates, and illustrates how the evolutionary functioning of such relationships can be diverse.     

Two new species of Odontocarya sect. Somphoxylon (Menispermaceae) from South America

Odontocarya monandra Barneby, resembling O. deminuta in glabrous staminate panicle, 3-merous corolla and solitary stamen, but notably different in shape and venation of leaves and larger staminate flowers, is described from Prov. Maynas, northeastern Peru; and O. septemfida Barneby, the only known member of the genus with lobed leaves, from Edo. Falcón, Venezuela.     

Preformation and distribution of staminate and pistillate flowers in growth units of Nothofagus alpina and N. obliqua (Nothofagaceae)

Background and Aims

The distribution and differentiation times of flowers in monoecious wind-pollinated plants are fundamental for the understanding of their mating patterns and evolution. Two closely related South American Nothofagus species were compared with regard to the differentiation times and positions of staminate and pistillate flowers along their parent growth units (GUs) by quantitative means.

Methods

Two samples of GUs that had extended in the 2004–2005 growing season were taken in 2005 and 2006 from trees in the Lanín National Park, Patagonia, Argentina. For the first sample, axillary buds of the parent GUs were dissected and the leaf, bud and flower primordia of these buds were identified. The second sample included all branches derived from the parent GUs in the 2005–2006 growing season.

Key Results

Both species developed flowering GUs with staminate and/or pistillate flowers; GUs with both flower types were the most common. The position of staminate flowers along GUs was similar between species and close to the proximal end of the GUs. Pistillate flowers were developed more distally along the GUs in N. alpina than in N. obliqua. In N. alpina, the nodes bearing staminate and pistillate flowers were separated by one to several nodes with axillary buds, something not observed in N. obliqua. Markovian models supported this between-species difference. Flowering GUs, including all of their leaves and flowers were entirely preformed in the winter buds.

Conclusions

Staminate and pistillate flowers of N. alpina and N. obliqua are differentiated at precise locations on GUs in the growing season preceding that of their antheses. The differences between N. alpina and N. obliqua (and other South American Nothofagus species) regarding flower distribution might relate to the time of anthesis of each flower type and, in turn, to the probabilities of self-pollination at the GU level.Key words: Branch, bud, growth unit, Markovian models, Nothofagus alpina, N. obliqua, Patagonian forests, pistillate flower, preformation, staminate flower     

Kenilanthus,a new eudicot flower with tricolpate pollen from the Early Cretaceous (early-middle Albian) of eastern North America

A new Early Cretaceous flower, Kenilanthus marylandensis, is described from the fossil plant bearing sequence exposed in early-middle Albian Potomac Group sediments at the Kenilworth (Bladensburg) locality, Maryland, USA. The flower is small, actinomorphic, pentamerous, and isomerous, and contains both pistillate and staminate parts. The receptacle is slightly dome-shaped and bears one whorl of five tepals, with a possible additional whorl toward the outside, ten stamens in two whorls of five, and one whorl of five free carpels. Stamens have elongate, tetrasporangiate, dithecate anthers that arc slightly inwards towards the centre of the flower. Thecae protrude and are oriented outwards. Pollen grains are small, tricolpate and reticulate with a graded, heterobrochate reticulum and segmented, spiny muri. Carpels are elongate with abundant stomata on the outer surface, and each carpel has a broad oblique base. Ovules are numerous in each carpel and are borne on two marginal placentae that extend along either side of the ventral suture. Kenilanthus has a combination of features that occur among different early-diverging eudicot lineages, suggesting a phylogenetic position close to the base of the eudicot clade, but its precise phylogenetic position is difficult to resolve.     

Anther structure and pollen development in Melicoccus lepidopetalus (Sapindaceae): An evolutionary approach to dioecy in the family

Anther and pollen development in staminate and pistillate flowers of dioecious Melicoccus lepidopetalus (Sapindaceae) were examined by light and electron microscopy. Young anthers are similar in both types of flowers; they consist of epidermis, endothecium, two to four middle layers and a secretory tapetum. The microspore tetrads are tetrahedral. The mature anther in staminate flowers presents compressed epidermal cells and endothecium cells with fibrillar thickenings. A single locule is formed in the theca by dissolution of the septum and pollen grains are shed at two-celled stage. The mature anthers of pistillate flowers differ anatomically from those of staminate flowers. The epidermis is not compressed, the endothecium does not develop fibrillar thickenings, middle layers and tapetum are generally persisting, and the stomium is nonfunctional. Microspore degeneration begins after meiosis of microspore mother cells. At anthesis, uninucleate microspores and pollen grains with vegetative and generative nuclei with no cytokinesis are observed. Some pollen walls display an abnormal exine deposition, whereas others show a well formed exine, although both are devoid of intine. These results suggest that in the evolution towards unisexuality, the developmental differences of anther wall tissues and pollen grains between pistillate and staminate flowers might become more pronounced in a derived condition, such as dioecy.     

Plant community distribution along water table and grazing gradients in montane meadows of the Sierra Nevada Range (California, USA)

This study aimed to identify dominant plant communities across five wet and mesic meadows in the Sierra Nevada Range (California, USA) and examine the impacts of environmental and grazing gradients on plant community distribution and diversity. Species composition and environmental conditions were recorded in 100 plots over two years. Classification and ordination analyses were used to classify plant communities and identify relationships between community types and both environmental and grazing gradients. We identified the following six plant community types: Carex jonesii, Carex leporinella, Carex nebrascensis, Carex utriculata, Eleocharis pauciflora, and Veratrum californicum. We found strong connections between plant communities and water table variables, with low water table (r ²?=?0.56) and mean water table (r ²?=?0.30) significantly correlated with Axis 1 while high water table (r ²?=?0.29) and elevation were correlated with Axis 3 (r ²?=?0.49). We found significant differences among community types for all three water table variables and for elevation. We found no correlation between grazing and community type classification, but there was a significant difference in grazing levels among community types. The plant communities and relationships to water table found in this work may aid managers in understanding present conditions and identifying future changes in meadow ecosystems.     

FLORAL DEVELOPMENT IN MYRISTICA (MYRISTICACEAE)

Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second-order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third-order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four-sporangiate anthers or monocarpellate pistils.     

Pollination and floral scent differentiation in species of the Philodendron bipinnatifidum complex (Araceae)

The Philodendron bipinnatifidum complex of Philodendron subgenus Meconostigma may comprise four species, which because of only slight and not very distinct morphological differences are not all unanimously recognized as good species. To find out whether these species are reproductively isolated, we studied the flowering rhythm, thermogenesis and pollination biology of three species of this complex, namely of P. bipinnatifidum, P. aff. bipinnatifidum (provisionally named “P. form selloum”) and P. mello-barretoanum in Brazil. Of the first two mentioned taxa, floral scent was collected and scent compounds were identified by GC–MS. The results showed that the coastal forest species P. bipinnatifidum has a two-, or three-night flowering rhythm, with the pistillate stage in the first night and the staminate stage lasting the second and sometimes also the third night. Strong thermogenesis with extended heating periods of several hours during the first part of the usual two subsequent nights and the maximum temperatures of up to 40 °C absolute heating of the spadices occurred in the pistillate and staminate stages. Concomitant with the heating periods, relatively low amounts of principally (Z)-2-pentenyl acetate and (Z)-jasmone were emitted by both the pistillate and staminate stage inflorescences. The dynastid scarab beetle Cyclocephala variolosa was the only pollinator attracted. The upland forest P. form selloum always had a two-night flowering rhythm with the pistillate stage in the first and the staminate stage in the subsequent night. This world-record holder of thermogenesis can heat up to the remarkable 45 °C during a relatively short period in the evening of the pistillate stage. During the thermogenic period, enormous amounts of principally 4-methoxystyrene and 3,4-dimethoxystyrene were produced and which could attract a large number of female and male individuals of the dynastid scarab beetle Erioscelis emarginata. In the staminate stage of P. form selloum, temperature elevation is significantly lower and the scent compounds are different from the pistillate stage. The cerrado biome species P. mello-barretoanum has a flowering rhythm similar to P. form selloum, reaching a maximum heating of about 40 °C during the pistillate stage. The sole pollinator attracted was Cyclocephala atricapilla. The differences observed and analyzed among the taxa, including the flowering rhythm, thermogenic activities, scent compounds emitted, pollinating dynastid scarab beetles attracted, as well as slight morphological differences and apparent geographical exclusiveness noted in these three taxa are strong indicators that P. bipinnatifidum, P. form selloum and P. mello-barretoanum are different enough to be considered good species. The morphological affinities of these species might be a hint that speciation has been a recent event and/or also that reproductive isolation based on different, non-overlapping distribution areas, different scent compounds and different pollinators was effective enough to need further morphological differentiation.