Terrestrial Herbaceous Plants Research Articles

Convergent relationships between flower economics and hydraulic traits across aquatic and terrestrial herbaceous plants

Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance. Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorly understood. Here, we hypothesize that the coordination and trade-offs between floral hydraulics and economics traits are independent of environmental conditions. To test this hypothesis, we investigated a total of 27 flower economics and hydraulic traits in six aquatic and six terrestrial herbaceous species grown in a tropical botanical garden. We found that although there were a few significant differences, most flower hydraulics and economics traits did not differ significantly between aquatic and terrestrial herbaceous plants. Both flower mass per area and floral longevity were significantly positively correlated with the time required for drying full-hydrated flowers to 70% relative water content. Flower dry matter content was strongly and positively related to drought tolerance of the flowers as indicated by flower water potential at the turgor loss point. In addition, there was a trade-off between hydraulic efficiency and the construction cost of a flower across species. Our results show that flowers of aquatic and terrestrial plants follow the same economics spectrum pattern. These results suggest a convergent flower economics design across terrestrial and aquatic plants, providing new insights into the mechanisms by which floral organs adapt to aquatic and terrestrial habitats.

Influence of lignocellulosic components on the anaerobic digestibility of aquatic weeds: Comparison with terrestrial crops

Anaerobic digestion treatment of excessively growing aquatic weeds has been paid attention due to the energy recovery with low energy requirement. The effects of lignocellulosic components on anaerobic digestibility of terrestrial herbaceous plants have been extensively researched, not much work has been done on aquatic weeds. Because of the flexible structure, aquatic weeds' chemical compositions and anaerobic digestibility may differ from terrestrial plants. This study investigated the relationships between the amount and ratio of lignocellulosic components (cellulose, hemicellulose, and lignin) and the kinetic parameters (ultimate methane yield, maximum methane production rate, lag phase, and T80, which refers to the time required to produce 80% of the total methane) calculated using the modified Gompertz model. Negative correlations were found out not only between lignin contents and the ultimate methane yield but also between hemicellulose content and the maximum methane production rate. The correlations between cellulose/lignin and ultimate methane yield and between cellulose/hemicellulose and maximum methane production rate, suggesting these parameters were primarily regulated by the lignocellulosic ratios. The correlation between cellulose/lignin and ultimate methane yield including aquatic weeds and terrestrial plants was approximately fitted using the same equation. While the maximum methane production rate of aquatic weeds and terrestrial herbaceous plants was not fitted to one equation with cellulose/hemicellulose, correlated with cellulose/estimated xylose on the same equation. This might be because cellulose degradation was hindered by xylose owing to the bonding of cellulose to lignin, thus determining the degradation rate of cellulose. Therefore, while cellulose can be degraded and converted to methane, coverage by lignin and xylose limits cellulose degradability and thus regulated methane production from aquatic weed.

Leaf economics in a three‐dimensional environment: Testing leaf trait responses in vascular epiphytes to land use, climate and tree zone

Abstract The study of functional traits offers predictive power for community ecology. Particularly in cases where individual species are difficult to study, known properties of trait spectra, such as the leaf economics spectrum (LES), and trait–environment relationships can provide crucial generalizable information that can contribute to forecasts of distributional shifts in response to the abiotic effects of climate and land use changes. Vascular epiphytes have been proposed as indicators of environmental change, but we know little about the ecology of most species. Key functional trait assumptions are based on terrestrial plants; testing these in epiphytes verifies their universality and will inform applying functional traits in predicting epiphyte responses to climate and land use change. In this study, we use functional traits from 37 vascular epiphyte species from forests and shade coffee farms at two sites in northern Nicaragua. We compare correlations among traits and intraspecific trait variances with those of terrestrial plants and among epiphyte taxonomic groups. We also test trait responses to environmental differences between sites and land use types, and within zones of the tree. We find that epiphyte leaf traits fall towards the slower end of the LES, but with about one‐third lower leaf nitrogen per change in specific leaf area (SLA) relative to terrestrial herbaceous plants. Bromeliads show less relationship between these traits than other epiphyte groups and also deviate in other trait interrelationships, suggesting unique leaf construction. Trait–environment relationships varied most strongly along vertical gradients within trees, but some traits, including SLA and carbon isotope ratio, also responded to land use and site differences. We present evidence that trait relationships established for terrestrial plants appear to translate to epiphytes, but identify some possible caveats. Strong trait response to vertical gradients within trees suggests that within‐canopy shifts could provide resilience to climate and land use changes for some epiphyte species.

Generality and Shifts in Leaf Trait Relationships Between Alpine Aquatic and Terrestrial Herbaceous Plants on the Tibetan Plateau

Plant traits mirror both evolutionary and environmental filtering process with universal trait-trait relationships across plant groups. However, plants also develop unique traits precisely to different habitats, inducing deviations of the trait coupling relations. In this study, we aimed to compare the differences in leaf traits and examine the generality and shifts of trait-trait relationships between alpine aquatic and terrestrial herbaceous plants on the Tibetan Plateau, to explore the precise adaptive strategies of aquatic and terrestrial plants for its habitats. We measured mass-based and area-based leaf N and P concentrations, N:P ratios and specific leaf area (SLA) of aquatic and terrestrial herbaceous plants. Standardized major axis analysis were applied to build the correlations for every trait pairs of each plant group, and then to compare the differences in the trait-trait correlations among different plant groups. Leaf Nmass and Pmass of two groups of aquatic plants (emergent and submerged plants) were higher, but N:P ratios were lower than those of two groups of terrestrial plants (sedges and grasses). Submerged plants had extremely high SLA, while grasses had the lowest SLA. Nmass positively correlated with Pmass in three out of four plant groups. The two terrestrial plant groups had positive Nmass-SLA relationships but these two traits coupled weakly in aquatic plants. Pmass showed positive relationships to SLA in three out of four plant groups. Significant shifts of trait-trait relationships between aquatic and terrestrial plants were observed. In general, aquatic plants, especially submerged plants, are characterized by higher SLA, greater leaf nutrientmass than terrestrial plants, tend to pursue fast-return investment strategies, and represent the acquisitive end of leaf economics spectrum. The deviations of trait-trait relationships between different plant groups reveal the precise adaptions of submerged plants to the unique aquatic habitats.

Paleoclimate and Holocene relative sea-level history of the east coast of India

The Holocene sea-level history of the east coast of India is relatively unexplored. We analysed a 17.37-m-long sediment core from Kolleru Lake, a fresh waterbody located in a deltaic setting along the east coast of India, to reconstruct the climate, environmental, and sea-level history of the region. Sedimentary facies and pollen assemblages, with nine accelerator mass spectrometry 14C dates (two mollusk shells and seven plant samples) from the core revealed Holocene relative sea-level changes, and provide the first insights into the climate of the region from the Last Glacial Maximum (LGM) to present. A layer of anhydrous calcium sulfate at the core bottom, along with a 14C age of 18.4 cal ka BP, combined with the absence of pollen in mottled yellowish clay, indicated a desiccated lake surface, reflecting a dry LGM climate. Palynomorphs in the overlying calcareous-concretion-bearing light brown silty clay showed a change from arid terrestrial herbaceous plants to freshwater taxa, indicating a change from dry to wet climate after the LGM and before 8.0 cal ka BP. Further upward in the core, black, sticky silty clay with abundant mangrove pollen and mollusk shells indicated a marine environment in Kolleru Lake and aggradational sediment stacking related to the middle Holocene sea-level rise from 8.0 to 4.9 cal ka BP. The uppermost sandy/silty clay, with terrestrial/aquatic pollen and a 14C age of 3.7 cal ka BP indicated a freshwater environment during the late Holocene. Our results show that Kolleru Lake, on the east coast of India, changed from a desiccated state during the dry LGM to a brackish lagoon during the middle Holocene, and then to a freshwater lake by the late Holocene, under the influence of climate and relative sea-level changes.

Economic trade-offs of hydrophytes and neighbouring terrestrial herbaceous plants based on plant functional traits

This study aims to compare variation and co-variation of leaf, stem and root economic traits between hydrophytes and sympatric terrestrial plants, and further to explore the ecological strategies of the aquatic plants. We collected data for 145 species from 38 sites in Shaanxi Province, including 60 aquatic species and 85 terrestrial species (112 genera and 48 families). Fifteen plant economic traits of these species were measured, including specific leaf area, dry matter content and C, N, P stoichiometry in leaves, stems and roots. Multivariate analysis was employed to uncover the differences in economic trade-offs between aquatic and terrestrial plants. The results indicated that: (1) Hydrophytes exhibited much higher specific leaf area and lower mean leaf dry matter content, stem dry matter content, root dry matter content, stem carbon content and root carbon content compared with that of terrestrial plants in order to adapt to the aquatic environment, that is, there were differences in mean traits about the economic trade-offs faced by hydrophytes and terrestrial plants. (2) The leaf economic spectrum of aquatic plants in this region coincided with the worldwide leaf economics spectrum, while hydrophytes are located at the extreme of thin leaves which is conducive to rapid acquisition of resources. (3) Aquatic and terrestrial species can be discriminated by few functional traits related to resource acquisition and support tissues. (4) Aquatic and terrestrial plants differed in bivariate correlations between certain economic traits (standardized major axis analysis), indicating differences in plant strategies.

Hydrology Drives Vegetation Succession in a Tidal Freshwater Wetland of Subtropical Taiwan

The relationships between vegetation communities and environmental variables in tropical/subtropical tidal freshwater wetlands are poorly understood. We tracked the vegetation succession of the Huajiang wetland in northern Taiwan for 10 years since its emergence in 2000, likely due to massive sediment deposition caused by typhoon floods. The aquatic plant Phragmites australis expanded and dominated the wetland within the first four years, after which terrestrial herbaceous plants appeared. In 2007, woody plants were found scattered in the wetland. In 2010, the vegetation communities became more diverse. Along the gradient of increasing elevation with decreasing soil water content, three vegetation zones were distinguished: aquatic, terrestrial, and transitional. Along the second gradient of distances from the nearest tidal creek, the transitional zone could be further differentiated into more aquatic and more terrestrial zones. Our results indicate that hydrology engaging soil moisture and sedimentation was the major force driving the vegetation succession in the tidal freshwater wetland. These findings suggest that the vegetation community in tidal freshwater wetlands can be used as an indicator to monitor management measures and assess the impacts within the wetland and catchment.

δD values of n-alkanes in sediments from Gahai Lake, Gannan, China: implications for sources of organic matter

Gahai Lake in the Gannan region, located in the northeast of the Tibetan Plateau, is the largest pristine freshwater lake on the plateau. Surface sediments in the Gahai Lake were systematically sampled, and n-alkane distribution and hydrogen isotope were analyzed by a gas chromatograph-mass spectrometer and a gas chromatograph-interface-isotope ratio mass spectrometer. The δD values of n-alkanes in the sediments ranged from −247 to −161 ‰ and the mean values varied between −222 and −182 ‰. The studied sediments were divided into types I and II based on the average δD values of n-alkanes. The average δD values of n-alkanes in type I sediments were significantly higher than those in type II sediments and there were good correlations among the δD values of the n-alkanes from the two sediment types. The δD values of type I sediments indicated that the C21–C33 odd-numbered n-alkanes were derived mainly from aquatic plants in the Gahai Lake, while the δD values of type II sediments showed that C27–C33 odd-number n-alkanes were derived from terrestrial herbaceous plants. This assessment of n-alkane sources was also confirmed by their distributions. It was inferred that the medium-chain length n-alkanes of relatively high abundance, low δD values, and low carbon preference index values were derived principally from bacteria. The distribution patterns of the sedimentary n-alkane δD values for the plateau humid-climate freshwater lake and dry-climate saline lake systems were compared. The results further confirmed that sedimentary n-alkanes record the hydrogen isotopic composition of source water used by organisms. Therefore, δD values of sedimentary n-alkanes can be used as geochemical indicators for sources of sedimentary organic matter and in paleoclimate studies. Our results also showed that the δD values of n-alkanes from sediments within the lake can differ significantly for a given time period owing to their different biological sources. This should be taken into account when reconstructing paleoclimatic and hydrologic conditions using sedimentary n-alkane δD values.

Stable isotope analysis reveals relative influences of seasonal hydrologic variation and impoundment on assimilation of primary production sources by fish in the Upper Yesilırmak River, Turkey

This study analyzed variation in stable isotope ratios of aquatic and terrestrial primary producers and two common cyprinid fishes (Capoeta banarescui and Squalius cephalus) at seven sites in the upper Yesilirmak River Basin, Turkey, to estimate relative contributions of basal production sources to fish biomass. We hypothesized that seasonal and spatial variation in fish assimilation of basal production sources would be affected by hydrological variation, with results for a reach downstream from a reservoir differing from those from upstream sites. Carbon and nitrogen isotopic ratios of primary producers and S. cephalus and δ15N of C. banarescui revealed significant spatial variation. δ13C of primary producers, δ15N of S. cephalus, and both δ13C and δ15N of C. banarescui revealed significant seasonal variation. C. banarescui biomass in the river channel was mostly derived from terrestrial herbaceous plants, and its biomass in the reservoir derived mostly from aquatic plants. Estimated proportional contributions of herbaceous plants to both species were greatest at the downstream site during spring, and declined during summer in the case C. banarescui. Overall, the influence of the dam was small relative to effects from watershed characteristics and seasonal changes in temperature and hydrology.

Determinants of fern and angiosperm herb community structure in lower montane rainforest in Indonesia

AbstractQuestionsDo ferns, which are physiologically less well adapted to conserve water than angiosperms but have more efficient propagule dispersal, show different vegetation–environment relationships than co‐occurring angiosperm herbs? We hypothesized that ferns should show closer relationships to local environmental conditions and might be more closely associated with humid and shady microhabitats.LocationPono and Bariri, two sites in lower montane primary tropical forest, Lore Lindu National Park, Central Sulawesi, Indonesia.MethodsAt each site, all terrestrial herbaceous plants were sampled in 200 plots of 5 m × 5 m. Sixteen environmental factors describing soils, topography and canopy openness were recorded. Correlations were calculated to test the degree of similarity in the species richness and turnover of ferns and angiosperms, and their relationships with environmental factors. Species optima were calculated on each environmental axis and compared between plant groups via randomization tests.ResultsIn total, 184 herb morphospecies were encountered at Pono and 135 at Bariri, of which almost 60% at each site were ferns. At both sites, fern species turnover showed closer correlations with soil variables than did angiosperm turnover. At the more topographically heterogeneous site (Bariri) fern species turnover was also more closely associated with topographic differences than was angiosperm turnover. Habitat preferences of ferns and angiosperms appeared more similar at Bariri than Pono, with both tending towards lower topographic positions and richer soils, but steeper slopes, than expected at random. At Bariri, neither plant group tended towards shady microsites, whereas at Pono ferns were better represented than angiosperms in microhabitats with open canopies.ConclusionsAs expected, ferns showed closer correlations with environmental factors than angiosperm herbs. Ferns did not, however, consistently favour humid microhabitats at both sites, and were not significantly associated with shady microhabitats at either site. Furthermore, it appears that physiological differences in water use do not lead to marked divergence in fern and angiosperm herb distributions in the humid understorey of this lower montane rainforest.

Characterisation of n-alkanes and their hydrogen isotopic composition in sediments from Lake Qinghai, China

The distributions of n-alkanes and their hydrogen isotopic composition (δD) in surface and core sediments from the saline Qinghai Lake were measured to assess whether or not biological source information was recorded in the δD values of n-alkanes. The results indicate that the n-alkane distributions between shallow water surface and core sediments were similar, and closer to those of terrestrial herbaceous plants from the Qinghai Lake surrounding areas, rather than the aquatic plants living in the lake. The n-alkanes in the surface and core sediments had similar mean δD values, ranging from −185‰ to −133‰ and −163‰ to −142‰, respectively. The mean δD values of n-alkanes in the sediments showed that the even n-alkanes were heavier in D compared with the odd homologues.

Transpiration estimation of banana (Musa sp.) plants with the thermal dissipation method

The banana (Musa sp.) plant is one of the largest monocotyledoneous terrestrial herbaceous plants in the world. The measurement of transpiration (Tr) for a whole banana plant is always difficult to perform due to its size. However, the sap flow (SF) of the plant has been successfully measured by using the thermal dissipation probe (TDP) or ‘Granier’ method in the corm of the banana plant (Lu et al. J Exp Bot 53:1771–1779, 2002). The present study aimed to validate their method using a sizable number of banana plants in a greenhouse in Israel. The SF data was compared to the gravimetric measurement of transpiration. The lag time of SF behind Tr was also analyzed. Results showed that the daily SF agreed with the daily Tr when the effective radius for sap flow in the corm was taken as 0.63 R, where R is the radius of the corm. The SF lagged 45 min behind the Tr from 0630 to 1040 hours. Whereas the Tr was not statistically (P>0.05) different from the SF between 1330 and 1700 hours. The reduction in water capacity of banana plant due to SF lag was about 10.5% of the daily Tr, and it recovered gradually in the afternoon. Using more plants can reduce the measurement error of the TDP method. The measured daily SF can be considered as an accurate estimation of the daily Tr for banana plant.

The ghost of hybridization past: niche pre-emption is not the only explanation of apparent monophyly in island endemics.

Summary 1 Published molecular phylogenies show that many plant groups in the Canary Islands are monophyletic despite the fact that the short distance between the islands and Africa should have led to many independent colonization events. 2 Low establishment rates of later migrants owing to niche pre-emption by earlier, already established, colonists could explain these patterns. The apparent monophyly is, however, also compatible with multiple colonizations, with later colonizers making only limited contributions to the total gene pool (and therefore being undetected in the molecular phylogeny) or being wiped out by stochastic processes. 3 Experimental evidence for niche pre-emption and species-specific interactions in plants is weak, with survival and establishment of a newly immigrant species depending on the overall composition of the community, rather than on the presence of a particular ‘ecologically similar’ species. 4 Although niche pre-emption might have contributed to the observed patterns of monophyly, we do not think that phylogeographical data from Macaronesia can be taken as evidence for its action in the geological past.

Relative competitive performance of 63 species of terrestrial herbaceous plants

Abstract. There is growing evidence that plant and animal species are arranged in hierarchies of relative competitive performance. More work is needed to determine which plant traits best predict relative competitive performance. We therefore measured relative competitive performance of 63 terrestrial herbaceous plant species using Trichostema brachiatum as a reference species (that is, phytometer or target species). The neighbour species came from a wide array of terrestrial vegetation types (e.g. rock barrens, alvars, old fields), and represented a wide array of growth forms (e.g. small rosette species such as Saxifraga virginiensis and large clonal graminoids such as Agropyron repens). The experiment was repeated with two pot sizes: large (control) and small (stress treatment). Relative competitive performance in large pots (controls) was highly correlated with that in small pots (stress treatment) (r= 0.90, p < 0.001). The hierarchy of relative competitive performance in the large pots was also highly correlated with the hierarchy in the small (stressed) pots (rs= 0.91, p < 0.001). Principal components analysis and multiple linear regression showed that plant size (measured by total biomass, above‐ground biomass, below‐ground biomass, canopy area, height and leaf area index) and leaf shape (measured as length to width ratio, length, width) were the two characteristics that best predicted relative competitive performance (large pots, r2= 0.55; small pots, r2= 0.48).

Relative competitive performance of 63 species of terrestrial herbaceous plants

There is growing evidence that plant and animal species are arranged in hierarchies of relative competitive performance. More work is needed to determine which plant traits best predict relative competitive performance. We there- fore measured relative competitive performance of 63 terres- trial herbaceous plant species using Trichostema brachiatum as a reference species (that is, phytometer or target species). The neighbour species came from a wide array of terrestrial vegetation types (e.g. rock barrens, alvars, old fields), and represented a wide array of growth forms (e.g. small rosette species such as Saxifraga virginiensis and large clonal graminoids such as Agropyron repens). The experiment was repeated with two pot sizes: large (control) and small (stress treatment). Relative competitive performance in large pots (controls) was highly correlated with that in small pots (stress treatment) (r = 0.90, p < 0.001). The hierarchy of relative competitive performance in the large pots was also highly correlated with the hierarchy in the small (stressed) pots (rs = 0.91, p < 0.001). Principal components analysis and multiple linear regression showed that plant size (measured by total biomass, above-ground biomass, below-ground biomass, canopy area, height and leaf area index) and leaf shape (mea- sured as length to width ratio, length, width) were the two characteristics that best predicted relative competitive perfor- mance (large pots, r2 = 0.55; small pots, r2 = 0.48).

Growth response of Equisetumfluviatile to elevated CO 2 and temperature

In contrast to crop plants and terrestrial herbaceous plants, aquatic plants have raised only modest interest among scientists working on climate change. However, climate change studies on emergent macrophytes can be justified with their crucial role in the ecosystem functioning of aquatic habitats. Here we present the results of a three-year study on the growth response of Equisetum fluviatile, a prominent littoral species of boreal lakes, to elevated CO 2 (doubled to 600–700 ppm) and temperature (increased 2.5–3 °C). Our findings reveal that temperature effects on this species were far more distinct than the effects of CO 2, and no interactions of temperature and CO 2 were observed. Temperature increase had a positive effect on the emergence of shoots and shoot length growth as well as on the maximum length of shoots. Maximum biomass was also positively affected by temperature. The enhancing effects of temperature were carried over to the next growing season. CO 2 enrichment also affected the maximum length of shoots, but the effect was negative. In addition, some response to CO 2 in fertility was observed, but again the effect of temperature was more obvious. Exposure to CO 2 enrichment seemed to have some positive effects on the belowground biomass of E. fluviatile, although this response was not very clear. Thus, we speculate that in the future climate this species will grow faster and the littoral stands will produce more shoot biomass.

Leaf nutrient resorption, leaf lifespan and the retention of nutrients in seagrass systems

Efficient nutrient resorption from senescing leaves, and extended leaf life spans are important strategies in order to conserve nutrients for plants in general. Despite the fact that seagrasses often grow in oligotrophic waters, these conservation strategies are not strongly developed in seagrasses. A compilation of literature data on nutrient resorption from seagrass leaves shows that the mean resorption of nitrogen is 20.4%, and that of phosphorus 21.9%, which is lower than comparable values for various groups of perennial terrestrial plants. The actual realised resorption in seagrasses may be even less as a result of premature losses of leaf fragments due to herbivory and hydrodynamic stresses, and due to leaching losses. The leaf lifespan in seagrasses on average is 88.4 days, but is highly variable, ranging from 345 days in Posidonia oceanica to only a few days in Halophila ovalis. Leaf lifespan increases with increasing leaf weight, and decreases with increasing leaf formation rate. Furthermore, leaf longevity increases going from tropical to temperate latitudes. We compared seagrass leaf lifespan with those of freshwater angiosperms, terrestrial herbaceous plants, shrubs and trees. Considerable variability in leaf lifespan was also found in these plant groups, but comparison among data sets shows that seagrass leaf lifespan is significantly lower than the leaf lifespan of terrestrial herbaceous plants, shrubs and trees. No significant difference was found between the leaf lifespan of seagrasses and freshwater angiosperms. Leaves are usually the major sink for nutrients in seagrasses. The combination of low nutrient resorption from the leaves and a short leaf lifespan is, therefore, expected to result in a low nutrient residence time in the plants. Indeed, field experiments with 15N labelled Thalassia hemprichii showed that less than 5% of the initial 15N amount was still within the living plant biomass 240 days after labelling. Limited nutrient retention in the plant biomass necessitates the capture of new nutrients for persistent growth. We speculate that effective nutrient uptake by seagrass leaves is an important strategy to maintain an adequate nutrient balance in seagrasses, particularly in thin vegetation or in small patches. The constraints imposed by the marine environment may have favoured the development of this strategy over the development of efficient nutrient conservation strategies.

Studies on the flora of the Guianas n° 84. New records for French Guiana, 1992–1994

Hoff, M., Cremers, G., Boggan, J.: Studies on the flora of the Guianas no 84. New records for French Guiana, 1992–1994. − Willdenowia 26: 301−320. 1996. − ISSN 0511−9618. The species richness of French Guiana is still imperfectly known. Based on an analysis of the entries in the ‘Flora of French Guiana database’, AUBLET, and the comparison with the checklist for the Guianas edited in 1992, its known flora grew richer within three years, from 1992 to 1994, by 308 new species and infraspecific taxa, i. e. at a rate of 5.9%. At present, the known flora of French Guiana consists of 5206 species and infraspecific taxa of higher plants (3662 dicotyledons, 1187 monocotyledons, 353 pteridophytes and 4 gymnosperms). The new records for French Guiana comprise 117 taxa already recorded from Surinam and/or Guyana, 92 taxa new for the three Guianas, 39 taxa new to science, 37 formerly doubtful and now confirmed records of taxa, and 23 new records of taxa of uncertain status. The vast majority of the new records is based on material collected within the last 30 years; two thirds come from the dense lowland forests, 60 % are trees, 30 % lianas and epiphytes, 10% terrestrial herbaceous plants.

Leaf life span of floating-leaved plants

Photosynthetic capacity of floating-leaved plants is relatively high comparable with terrestrial herbaceous plants, though floating-leaved plants have a much smaller biomass with a leaf area index seldom exceeding 2m2m-2. Their rather small biomass accumulation is related to higher turnover of leaf biomass or shorter leaf life span. Life span of floating leaves reported in the literature ranged mostly from 13 to 35 days, shorter than that of any other groups of herbaceous macrophytes. Floating-leaved plants are known to show considerably high plasticity in their leaf form. Leaf life span could be prolonged for Nymphoides peltata (Gmel.) O. Kuntze grown in a terrestrial environment and for emergent leaves of Nelumbo nucifera Gaertn. Their short leaf life span seems to be closely related to the fact that old leaves covered by newly formed ones are inevitably compelled to be submerged and lose their function as a photosynthetic apparatus.