| the influence of secondary senescence processes within the culm of a pseudoviviparous grass (poa alpina var. vivipara l.) on the supply of water to propagules. | an anatomical investigation of the culm of pseudoviviparous alpine meadow grass (poa alpina var. vivipara l.) revealed that transpiration flow, as delimited by lucifer yellow tracer dye, was maintained despite advanced senescence (as evidenced by loss of chlorophyll and chloroplasts), with leafy spikelets driving transpiration flow. transpiration flow was not hindered by cavitation or tylosis in older culms, the low frequencies of these senescence processes being bypassed via nodal plexi. despit ... | 2000 | 10948234 |
| can meristematic activity determine variation in leaf size and elongation rate among four poa species? a kinematic study. | we studied inherent variation in final leaf size among four poa spp. that live at different elevations. the average final length of leaf 7 of the main stem of the smallest species (poa alpina) was only one-half that of the largest species (poa trivialis); it was correlated with leaf elongation rate, but not with the duration of leaf elongation. a faster rate of leaf elongation rate was associated with (a) larger size of the zone of cell expansion, and (b) faster rates of cell production (per cel ... | 2000 | 11027732 |
| architectural and physiological heterogeneity within the synflorescence of the pseudoviviparous grass poa alpina var. vivipara l. | many biotypes of the northern-hemisphere arctic-alpine grass poa alpina l. reproduce asexually via prolification of the spikelet axis to produce dehiscing shoots. although capable of photosynthesis, the source-sink characteristics of these synflorescence systems are unknown, including the degree to which plantlets from different regions of the synflorescence are capable of providing for their own carbon requirements, or contributing to other sinks. photosynthetic rates within the paracladial zon ... | 2000 | 11053460 |
| ethylene emission and responsiveness to applied ethylene vary among poa species that inherently differ in leaf elongation rates. | a plant's ability to produce and respond to ethylene is essential for its vegetative growth. we studied whole-shoot ethylene emission and leaf growth responses to applied ethylene in four poa spp. that differ inherently in leaf elongation rate and whole-plant relative growth rate. compared with the fast-growing poa annua and poa trivialis, the shoots of the slow-growing species poa alpina and poa compressa emitted daily 30% to 50% less ethylene, and their leaf elongation rate was more strongly i ... | 2002 | 12114591 |
| leaf respiration in light and darkness (a comparison of slow- and fast-growing poa species). | we investigated whether leaf dark respiration (nonphotorespiratory mitochondrial co2 release) is inhibited by light in several poa species, and whether differences in light inhibition between the species are related to differences in the rate of leaf net photosynthesis. four lowland (poa annua l., poa compressa l., poa pratensis l., and poa trivialis l.), one subalpine (poa alpina l.), and two alpine (poa costiniana vick. and poa fawcettiae vick.) poa species differing in whole plant relative gr ... | 1997 | 12223656 |
| partitioning of electrons between the cytochrome and alternative pathways in intact roots. | to test the hypothesis that the cytochrome pathway is not invariably saturated when the alternative pathway is engaged, we titrated root respiration of several species with kcn (an inhibitor of the cytochrome pathway), both in the absence and presence of an inhibitor of the alternative pathway (salicylhydroxamic acid, sham). the slopes of the resultant kcn [rho] plots ([rho]cyt) were then used to determine whether the cytochrome pathway was saturated in each species. the species used were festuc ... | 1995 | 12228536 |
| litter of the hemiparasite bartsia alpina enhances plant growth: evidence for a functional role in nutrient cycling. | hemiparasitic angiosperms concentrate nutrients in their leaves and also produce high quality litter, which can decompose faster and release more nutrients than that of surrounding species. the impact of these litters on plant growth may be particularly important in nutrient-poor communities where hemiparisites can be abundant, such as the sub-arctic. we tested the hypothesis that plant growth is enhanced by the litter of the hemiparasite bartsia alpina, in comparison with litter of co-occurring ... | 2003 | 12684861 |
| pseudoviviparous reproduction of poa alpina var. vivipara l. (poaceae) during long-term exposure to elevated atmospheric co2. | pseudovivipary is an asexual reproductive strategy exhibited by some arctic/alpine grasses in which leafy plantlets are produced in place of seeds, with genetic conservation an advantage for stress tolerators in these nutrient-poor habitats. photosynthetic metabolism and the development of this reproductive system were investigated under varying nutrient availability and predicted future co(2) partial pressure (pco(2)). poa alpina var. vivipara l., grown at present ambient pco(2) or ambient plus ... | 2003 | 12714360 |
| [the relation of bulbil formation in poa alpina vivipara to photoperiodicity and frost]. | | 1953 | 13068387 |
| exposure of two upland plant species to acidic fogs. | a system is described for exposing large numbers of plants to acidic fogs. the system allows low volumes of treatment solutions to be provided at particle sizes chiefly in the 5-30 microm range (equivalent to fog/cloud droplets). plants of poa alpina l. and epilobium brunnescens were propagated from material collected in snowdonia, north wales and exposed to fog treatments at ph values of 2.5, 3.5, 4.5 and 5.6. there were 3 x 4 h exposures per week which provided a total of 6 mm deposition. supp ... | 1991 | 15092062 |
| microbial succession of nitrate-reducing bacteria in the rhizosphere of poa alpina across a glacier foreland in the central alps. | changes in community structure and activity of the dissimilatory nitrate-reducing community were investigated across a glacier foreland in the central alps to gain insight into the successional pattern of this functional group and the driving environmental factors. bulk soil and rhizosphere soil of poa alpina was sampled in five replicates in august during the flowering stage and in september after the first snowfalls along a gradient from 25 to 129 years after deglaciation and at a reference si ... | 2006 | 16913920 |
| changing leaf litter feedbacks on plant production across contrasting sub-arctic peatland species and growth forms. | plant species and growth forms differ widely in litter chemistry, which affects decay and may have important consequences for plant growth via e.g. the release of nutrients and growth-inhibitory compounds. we investigated the overall short-term (9.5 months) and medium-term (21.5 months) feedback effects of leaf litter quality and quantity on plant production, and tested whether growth forms can be used to generalise differences among litter species. leaf litter effects of 21 sub-arctic vascular ... | 2007 | 17089140 |
| changes in chloroplast ultrastructure in some high-alpine plants: adaptation to metabolic demands and climate? | the cytology of leaf cells from five different high-alpine plants was studied and compared with structures in chloroplasts from the typical high-alpine plant ranunculus glacialis previously described as having frequent envelope plus stroma protrusions. the plants under investigation ranged from subalpine/alpine geum montanum through alpine geum reptans, poa alpina var. vivipara, and oxyria digyna to nival cerastium uniflorum and r. glacialis. the general leaf structure (by light microscopy) and ... | 2007 | 17603748 |
| effects of temperature and light on the formation of chloroplast protrusions in leaf mesophyll cells of high alpine plants. | chloroplasts of many alpine plants have the ability to form marked, stroma-filled protrusions that do not contain thylakoids. effects of temperature and light intensity on the frequency of chloroplasts with such protrusions in leaf mesophyll cells of nine different alpine plant species (carex curvula all., leontodon helveticus merat., oxyria digyna (l.) hill., poa alpina l. ssp. vivipara, polygonum viviparum l., ranunculus glacialis l., ranunculus alpestris l., silene acaulis l. and soldanella p ... | 2007 | 17897406 |
| microsatellite diversity of the agriculturally important alpine grass poa alpina in relation to land use and natural environment. | the alpine meadow grass poa alpina is common in subalpine and alpine natural sites and agriculturally used land, where it is an important fodder grass. natural factors and human land use are supposed to have been shaping its genetic diversity for hundreds of years. the species comprises sexually and vegetatively reproducing plants. the aim of this study was to investigate the effects of agricultural land use, environmental factors and the mode of reproduction on the distribution of its microsate ... | 2007 | 17901059 |
| mesophyll freezing and effects of freeze dehydration visualized by simultaneous measurement of idta and differential imaging chlorophyll fluorescence. | infrared differential thermal analysis (idta) and differential imaging chlorophyll fluorescence (dif) were employed simultaneously to study the two-dimensional pattern of ice propagation in leaves and mesophyll freeze dehydration as detected by a significant increase of basic chlorophyll fluorescence (f(0)). idta and dif technique gave different insights into the freezing process of leaves that was highly species-specific. idta clearly visualized the freezing process consisting of an initial fas ... | 2008 | 18761699 |
| accessory chromosomes in poa alpina. | | 1948 | 18863984 |
| population dynamics along a primary succession gradient: do alpine species fit into demographic succession theory? | understanding processes and mechanisms governing changes in plant species along primary successions has been of major importance in ecology. however, to date hardly any studies have focused on the complete life cycle of species along a successional gradient, comparing pioneer, early and late-successional species. in this study it is hypothesized that pioneer species should initially have a population growth rate, lambda, greater than one with high fecundity rates, and declining growth rates when ... | 2009 | 19273477 |
| volatile constituents of festuca nigrescens, phleum alpinum and poa alpina from n. w. italian alpine pastures. | the composition of the volatile fractions of three important grasses from sub-alpine n.w. italian pastures, namely festuca nigrescens lam. non gaudin (chewing fescue), phleum alpinum l. (alpine timothy) and poa alpina l. (alpine bluegrass) was investigated. the fresh aerial parts were collected at the flowering stage during the summer season. the volatile oils obtained from green tissues by steam distillation in a clevenger-type apparatus, were analyzed by gc/fid and gc/ms. the oil yield was 0.0 ... | 2011 | 21366056 |