Long-term studies on phenology are rarely reported from arctic and alpine areas, but essential for understanding biotic abiotic controls flowering. We monitored first flowering day (FFD) 144 species in a subarctic-alpine area Swedish Lapland over period of 10 yr (1992-2001). Temperature global radiation were continuously, snowcover duration was observed. Thawing degree-days (exposure) the dominant environmental phenology. introduce lability index (LI) to describe interannual variability FFD...

Species in the ivesioid clade of Potentilla (Rosaceae) are endemic to western North America, an area that underwent widespread aridification during global temperature decrease following Mid-Miocene Climatic Optimum. Several morphological features interpreted as adaptations drought found clade, and many species occupy extremely dry habitats. Recent phylogenetic analyses have shown sister group this is section Rivales, a with distinct moist habitat preferences. This has led hypothesis...

A study of a number reproductive traits in two sympatric species Pedicularis northern Swedish Lapland, the subarctic‐alpine P lapponica and artic hursuta , revealed that life‐history strategies differ profoundly High fruit set low seed abortion rate, as m is common arctic plants late‐thawing habitats represents case extreme adversity selection rather than an indication ruderal strategy on other hand, typical K‐strategist (or stress‐tolerator) requiring longer period growth for optimal...

Several naturally occurring hybrids in Potentilla (Rosaceae) have been reported, but no molecular evidence has so far available to test these hypotheses of hybridization. We compared a nuclear and chloroplast gene tree identify topological incongruences that may indicate hybridization events the genus. Furthermore, monophyly phylogenetic position proposed segregated genera Argentina, Ivesia Horkelia tested. The systematic signal from two morphological characters, style- anther shape, also...

The occurrence of arbuscular mycorrhizal (AM) fungi was surveyed along a latitudinal gradient in Arctic Canada including Banks Island (73°N), Devon (74°N), Ellesmere (76°N), and the Magnetic North Pole at Ellef Ringnes (78°N). At Island, AM were present colonized high intensity all specimens Potentilla hookeriana Lehm. – pulchella R.Br., Arnica angustifolia Vahl, Erigeron uniflorus L. ssp. eriocephalus (Vahl ex Hornen.) Cronq. sampled. soil collected under these plants showed inoculum...

Abstract Hybridization has long been considered a source of taxonomic complexity in Rubus. This study uses molecular data to examine natural hybridization between R. caesius, facultatively agamospermous tetraploid subgenus Rubus (blackberries) and idaeus, sexual diploid Idaeobatus (raspberries). Both species are widespread Europe, them is postulated have given rise numerous species, including maximiformis picticaulis. We sequenced the nuclear ribosomal DNA internal transcribed spacer (ITS)...

The characters used for generic delimitation in Valerianaceae are discussed, and the South American genera Aretiastrum, Astrephia, Belonanthus, Phuodendron, Phyllactis , Stangea included genus Valeriana. Valeriana subgen. is emended to comprise all species with reduced number of anther locules.

Indumentum types of the leaves in 31 species <em>Potentilla</em> L. (<em>Rosaceae</em>) and four related genera, especially <em>Tylosperma</em> Botsch., <em>Schistophyllidium</em> (Juz. ex Fed.) Ikonn., <em>Drymocallis</em> Fourr. Rydb., <em>Sibbaldia</em> from Iran were investigated. ultrastructure was studied by scanning electron microscopy (SEM). SEM observation revealed three type classes based on leaf indumentum: 1)...

Under natural conditions pollen vectors act stochastically, and the order in which arrives can influence seed paternity. In a number of wind-pollinated taxa, however, fertilization does not occur immediately. It has been proposed that delayed promotes competition by providing "fair start" for tubes. To test this hypothesis we compared paternity after simultaneous consecutive pollinations with multiple donors Fraxinus excelsior. Additionally, investigated tube growth naturally pollinated...

Three new species of Valeriana from southern Ecuador are described and illustrated. plateadensis is found near the highest peak Cerro Plateado in Cordillera del Cóndor at 2900 m a.s.l. recognized by shrubby habit sessile, densely imbricate, spatulate leaves 3-lobed corollas. V. yacuriensis Lagunas Negras de Jimbura Parque Nacional Yacurí 3500 habit, petiolate xenophylloides Páramo Patococha 3400 its cushion growth form, crown trichomes leaf apex

Glacial events and the formation of ice-free areas serving as refugia for plants animals are important in shaping present patterns genetic diversity arctic areas. Beringia, situated northeastern Russia Alaska, has been pointed out a major refugium. This study focuses on historical biogeography circumpolar taxon Potentilla sect. Niveae. The taxonomy group is complex, most likely highly influenced by hybridization apomixis. cpDNA microsatellites together with AFLP fragments were used to map...

Background: In general, females of woody dioecious plants are expected to grow more slowly than males because the high cost associated with fruit bearing. Yet wind-pollinated species may invest relatively heavily in male reproduction, and various compensatory mechanisms can offset incurred costs, therefore apparent growth genders might be similar over a longer period time. Any cost-related disparities most pronounced mast flowering years, when female reproductive resource demand is highest....

A morphometric study of Potentilla nivea, P unijlora, and hookeriana, as well the close relative latter, furcata, has been carried out, quantitative data subjected to Canonical Discriminant Analysis. The four taxa belong arctic‐alpine section Niveae Potentilla, material for analysis was collected in Alaska, U. S. A. a priori defined groups are based on petiole hair type, qualitative, only, character traditionally used distinguish within sect. Niveae. types recognized previously by...

An investigation of the embryology Potentilla nivea was carried out using a confocal laser scanning microscope. The crassinucellate nature ovule as well presence multicellular archesporium confirmed. A “nucellar cap” builds up result mitotic divisions in parietal cell tissue and nucellar epidermis. Earlier reports that several mature megagametophytes are present each processes megasporogenesis megagametogenesis turned to differ from descriptions previous reports, we propose reinterpretation....

Three subgenera are currently recognized in the genus Monnina, which consists of approximately 175 species. This paper treats systematics Monnina subg. Pterocarya northwestern South America. The subgenus is a naturally coherent taxon characterized by dry, samaroid fruits. It ca. 25 species, 11 occur area concerned