Ultraviolet absorption and epidermal-transmittance spectra in foliage

We examined the UV absorption spectra and the epidermal-transmittance spectra (280–350 nm) of foliage from 42 plant species. Sun foliage was sampled from naturally growing individuals of seven species in each of six life forms comprising two evergreen groups (gymnosperms and angiosperms) and four deciduous angiosperm groups (trees, shrubs and vines, herbaceous dicotyledons and grasses). There were large differences in absorption spectra of whole-leaf extracts among species. While absorbance declined with increasing wavelength in most woody species, there was a trough in absorbance around 300 nm in many herbaceous species. Absorption spectra were negatively correlated with epidermal-transmittance spectra in 31 of the 42 species. Relationships between absorbance and transmittance did not follow the theoretical exponential function. Species rankings of UV-screening effectiveness were similar when we assessed it by using epidermal transmittance at single wavelengths (300 or 320 nm) or different UV-action spectra to weight epidermal-transmittance spectra and estimate the levels of biologically effective UV reaching the mesophyll. Thus, differences in absolute epidermal transmittance among species appeared to overshadow spectral differences. Nevertheless, the differences we found in the internal UV spectral regime in foliage suggest that whole-plant action spectra will differ among species. While species rankings of UV-screening effectiveness were similar when different action spectra were used, the absolute amounts of biologically effective UV reaching the mesophyll of species varied considerably when different action spectra were used.     

Purification of lumazine proteins from Photobacterium leiognathi and Photobacterium phosphoreum: bioluminescence properties

Bright strains of the marine bioluminescent bacterium Photobacterium leiognathi produce a "lumazine protein" in amounts comparable to that previously found in Photobacterium phosphoreum. New protocols are developed for the purification to homogeneity of the proteins from both species in yields up to 60%. In dimmer strains the amounts of lumazine protein in extracts are less, and also there is an accompanying shift of the bioluminescence spectral maximum to longer wavelength, 492 nm. Both types of lumazine proteins have identical fluorescence spectra, with maxima at 475 nm, so it is suggested that, whereas lumazine protein is the major emitter in bright strains, there is a second emitter also present with a fluorescence maximum at longer wavelength. The two species of lumazine protein have the same 276 nm/visible absorbance ratio, 2.2, but differ in visible maxima: P. phosphoreum, 417 nm; P. leiognathi, 420 nm. For the latter the bound lumazine has epsilon 420 = 10 100 M-1 cm-1, practically the same as in free solution. The two lumazine proteins also differ quantitatively in their effect on the in vitro bioluminescence reaction, i.e., at blue shifting the bioluminescence spectrum or altering the kinetics. The P. phosphoreum lumazine protein is more effective with its homologous luciferase or with P. leiognathi luciferase than is the lumazine protein from P. leiognathi. These differences may have an electrostatic origin.     

Spectral differentiation of blue opsins between phylogenetically close but ecologically distant goldfish and zebrafish

Zebrafish and goldfish are both diurnal freshwater fish species belonging to the same family, Cyprinidae, but their visual ecological surroundings considerably differ. Zebrafish are surface swimmers in conditions of broad and shortwave-dominated background spectra and goldfish are generalized swimmers whose light environment extends to a depth of elevated short wavelength absorbance with turbidity. The peak absorption spectrum (lambdamax) of the zebrafish blue (SWS2) visual pigment is consistently shifted to short wavelength (416 nm) compared with that of the goldfish SWS2 (443 nm). Among the amino acid differences between the two pigments, only one (alanine in zebrafish and serine in goldfish at residue 94) was previously known to cause a difference in absorption spectrum (14-nm lambdamax shift in newt SWS2). In this study, we reconstructed the ancestral SWS2 pigment of the two species by applying likelihood-based Bayesian statistics and performing site-directed mutagenesis. The reconstituted ancestral photopigment had a lambdamax of 430 nm, indicating that zebrafish and goldfish achieved short wavelength (-14 nm) and long wavelength (+13 nm) spectral shifts, respectively, from the ancestor. Unexpectedly, the S94A mutation resulted in only a -3-nm spectral shift when introduced into the goldfish SWS2 pigment. Nearly half of the long wavelength shift toward the goldfish pigment was achieved instead by T116L (6 nm). The S295C mutation toward zebrafish SWS2 contributed to creating a ridge of absorbance around 400 nm and broadening its spectral sensitivity in the short wavelength direction. These results indicate that the evolutionary engineering approach is very effective in deciphering the process of functional divergence of visual pigments.     

Near infrared spectral changes of cytochrome aa3 during potentiometric titrations.

Singular value decomposition (SVD) was used to deconvolute the spectral changes occurring in the near infrared region during potentiometric titrations of cytochrome aa3. Overall oxidized minus reduced difference spectra revealed a broad absorbance feature centered near 830 nm with an apparent Em near 250 mV. However, SVD did not isolate any spectral species with an absorbance centered near 830 nm. It was found that the spectral changes occurring in the wavelength region from 650 to 950 nm were associated mainly with cytochromes a and a3. It was concluded that the absorbance at 830 nm should not be used as an independent measure of the concentration of CuA in cytochrome aa3.     

Visual pigments, cone oil droplets and ocular media in four species of estrildid finch

A microspectrophotometric study was conducted on the retinal photoreceptors of four species of bird: cut-throat finches (Amadina fasciata), gouldian finches (Erythrura gouldiae), white-headed munias (Lonchura maja) and plum-headed finches (Neochmia modesta). Spectral characteristics of the photoreceptors in all four species were very similar. Rods contained a medium-wavelength-sensitive visual pigment with a wavelength of maximum absorbance at 502-504 nm. Four spectrally distinct types of single cone contained a visual pigment with wavelength of maximum absorbance at either 370-373 nm (ultraviolet-sensitive), 440-447 nm (short-wavelength-sensitive); 500 nm (medium-wavelength-sensitive) or 562-565 nm (long-wavelength-sensitive). Oil droplets in the ultraviolet-sensitive single cones showed no detectable absorption between 330 nm and 800 nm. Oil droplets in the short-, medium-, and long-wavelength-sensitive single cones had cut-off wavelengths at 415-423 nm, 510-520 nm and 567-575 nm, respectively. Double cones contained the visual pigment with wavelength of maximum absorbance at 562-565 nm observed in long-wavelength-sensitive single cones. Only the principal member of the double cone pair contained an oil droplet (P-type, cut-off wavelength at 414-489 nm depending on species and retinal location). Spectral transmittance of the intact ocular media of each species was measured along the optic axis. Wavelengths of 0.5 transmittance for all species were very similar (316-318 nm).     

Correlating species and spectral diversities using hyperspectral remote sensing in early‐successional fields

Advances in remote sensing technology can help estimate biodiversity at large spatial extents. To assess whether we could use hyperspectral visible near‐infrared (VNIR) spectra to estimate species diversity, we examined the correlations between species diversity and spectral diversity in early‐successional abandoned agricultural fields in the Ridge and Valley ecoregion of north‐central Virginia at the Blandy Experimental Farm. We established plant community plots and collected vegetation surveys and ground‐level hyperspectral data from 350 to 1,025 nm wavelengths. We related spectral diversity (standard deviations across spectra) with species diversity (Shannon–Weiner index) and evaluated whether these correlations differed among spectral regions throughout the visible and near‐infrared wavelength regions, and across different spectral transformation techniques. We found positive correlations in the visible regions using band depth data, positive correlations in the near‐infrared region using first derivatives of spectra, and weak to no correlations in the red‐edge region using either of the two spectral transformation techniques. To investigate the role of pigment variability in these correlations, we estimated chlorophyll, carotenoid, and anthocyanin concentrations of five dominant species in the plots using spectral vegetation indices. Although interspecific variability in pigment levels exceeded intraspecific variability, chlorophyll was more varied within species than carotenoids and anthocyanins, contributing to the lack of correlation between species diversity and spectral diversity in the red‐edge region. Interspecific differences in pigment levels, however, made it possible to differentiate these species remotely, contributing to the species‐spectral diversity correlations. VNIR spectra can be used to estimate species diversity, but the relationships depend on the spectral region examined and the spectral transformation technique used.     

Protochlorophyll forms in roots of dark-grown plants

Protochlorophyll was found in roots of dark-grown plants of seven species investigated. It was identified by absorbance and fluorescence spectra of acetone and ether extracts. Chlorophyll was also found in roots of one pea species. The concentration of protochlorophyll was usually highest in young root tips and decreased upwards along the roots. The maxima of the in vivo absorbance spectra of the species studied varied between 634 and 638 nm. Low temperature in vivo fluorescence emission spectra had two maxima, one at ca 633 and the other at ca 642 nm, when the wavelengths of the excitation light were 440 and 460 nm, respectively. In vivo fluorescence excitation spectra displayed a shift of the excitation maximum from 438 to 445 nm, when emission varied from 620 to 647.5 nm. Deconvolution of these three types of spectra into Gaussian components made it possible to identify two spectral forms of protochlorophyll: protochlorophyll_629–633 and protochlorophyll_638–642.     

Phycobiliprotein fluorescence of Nostoc punctiforme changes during the life cycle and chromatic adaptation: characterization by spectral confocal laser scanning microscopy and spectral unmixing

Many cyanobacteria are highly adaptable to light quality, and many species undergo a complex life cycle. In this study we show that adaptive changes in the photosynthetic apparatus of cyanobacteria are not only caused by environmental, but also by developmental factors. Spectral confocal laser scanning microscopy (CLSM) was used to analyse in vivo the fluorescence spectra of the photosynthetic pigments chlorophyll a (Chl a), allophycocyanin (APC), phycocyanin (PC) and phycoerythrin (PE) of two Nostoc punctiforme strains. Changes in pigment fluorescence emission occurred in different developmental stages. Strain 1:1-26 showed an emission maximum at 674 nm in motile hormogonia stages, whereas vegetative stages showed maxima at 658 and 575 nm. These changes were not caused by chromatic adaptation. In contrast, the second strain (1:1-26lg) showed distinct fluorescence spectra, pigment localization and clear chromatic adaptation in red light. When these properties are known, both strains can be easily distinguished by the spectral CLSM method, which also allows the localization of the pigments within single cells. To calculate the contribution of individual phycobiliproteins to the observed changes, fluorescence spectra were analysed by spectral unmixing. This allowed the mathematical estimation of fluorescence shares for the individual phycobiliproteins in different developmental stages and both before and after chromatic adaptation. It is concluded that care should be taken when characterizing cyanobacteria by differences in pigment fluorescence, because these differences are influenced not only by chromatic adaptation, but also developmental stages. Spectral CLSM offers a powerful method to study the phycobiliprotein composition in vivo.     

Temperature dependence of optical properties of chlorophyll a incorporated into phosphatidylcholine liposomes

Temperature-dependent spectral changes of chlorophyll a (Chl a) incorporated into liposomes of two types of phosphatidylcholine are studied. When Chl a incorporated into the liposomes is cooled down to 5°C from the temperature of the gel-to-liquid crystalline phase transition of the lipid, the red shift as well as the increase in half-bandwidth of the red peak of Chl a are only slight. By measuring the difference spectra produced by substracting the absorption spectrum at the phase transition temperature of the lipid from that at lower temperature, it is shown that the component absorbing at longer wavelength (675–685 nm) than the peak of the red maximum (about 670 nm) significantly increases at the expense of the component absorbing at shorter wavelength (657–668 nm). The positions of positive and negative peaks depend on the temperature and the molar ratio of the lipid to Chl a. The absorbance change is most pronounced on cooling below the phase transition temperature of the lipid. The temperature-induced absorbance change is almost completely reversible. The results indicate that the aggregated forms of Chl a in liposomes can be spectrophotometrically detected in the gel phase of the lipid.     

Protein helical structure determination using CD spectroscopy for solutions with strong background absorbance from 190 to 230 nm

Conventional empirical methods for the quantification of the helical content of proteins in solution using circular dichroism (CD) primarily rely on spectral data acquired between wavelengths of 190 and 230 nm. The presence of chemical species in a protein solution with strong absorbance within this range can interfere with the ability to use these methods for the determination of the protein's helical structure. The objective of this research was to overcome this problem by developing a method for CD spectral analysis that relies on spectral features above this wavelength range. In this study, we determined that the slopes of CD spectra acquired over the 230 to 240 nm region strongly correlate with the helix contents including α-helix and 3₁₀-helix of protein as determined using conventional CD algorithms that rely on wavelengths between 190 and 230 nm. This approach (i.e., the 230–240 nm slope method) is proposed as an effective method to determine the helix content within proteins in the presence of additives such as detergents or denaturants with high absorbance of wavelengths up to 230 nm.     

Induction of multiple cytochrome P-450 species in housefly microsomes--SDS-gel electrophoresis studies.

1. Microsomal fractions isolated from various housefly strains have been characterized with respect to multiple forms of cytochrome P-450 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 2. Susceptible NAIDM houseflies were pretreated with known inducers of cytochrome P-450, and their microsomal electrophoretic profiles were compared to control NAIDM microsomes, using as standards partially purified cytochrome P-450s from noninduced NAIDM houseflies. 3. Tentatively, at least five different species of cytochrome P-450 may exist in the NAIDM housefly strain. 4. A comparison of the microsomal electrophoretic profile of different housefly strains also indicates the presence of at least two additional cytochrome P-450 species. 5. Induction with alpha-pinene and phenobarbital was expressed by a shift of the maximum absorbance at 452 nm in the CO-difference spectrum to lower wavelengths in the NAIDM strain; whereas, beta-naphthoflavone, although increasing the amount of cytochrome P-450, did not change the wavelength of maximum absorbance. 6. Cytochromes of the P-452 type appear to predominate in the susceptible NAIDM strain, while cytochromes of the P-450 and P-448 types predominate in resistant strains.     

Red Light Stimulates Feeding Motivation in Fish but Does Not Improve Growth

Nile tilapia fish were individually reared under similar light levels for 8 weeks under five colored light spectra (maximum wavelength absorbance): white (full light spectrum), blue (∼452 nm), green (∼516 nm), yellow (∼520 nm) or red (∼628 nm). The effects of light on feeding, latency to begin feeding, growth and feed conversion were measured during the last 4 weeks of the study (i.e., after acclimation). We found that red light stimulates feeding, as in humans, most likely by affecting central control centers, but the extra feeding is not converted into growth.     

Gene duplication is an evolutionary mechanism for expanding spectral diversity in the long-wavelength photopigments of butterflies

Butterfly long-wavelength (L) photopigments are interesting for comparative studies of adaptive evolution because of the tremendous phenotypic variation that exists in their wavelength of peak absorbance (lambda(max) value). Here we present a comprehensive survey of L photopigment variation by measuring lambda(max) in 12 nymphalid and 1 riodinid species using epi-microspectrophotometry. Together with previous data, we find that L photopigment lambda(max) varies from 510-565 nm in 22 nymphalids, with an even broader 505- to 600-nm range in riodinids. We then surveyed the L opsin genes for which lambda(max) values are available as well as from related taxa and found 2 instances of L opsin gene duplication within nymphalids, in Hermeuptychia hermes and Amathusia phidippus, and 1 instance within riodinids, in the metalmark butterfly Apodemia mormo. Using maximum parsimony and maximum likelihood ancestral state reconstructions to map the evolution of spectral shifts within the L photopigments of nymphalids, we estimate the ancestral pigment had a lambda(max) = 540 nm +/- 10 nm standard error and that blueshifts in wavelength have occurred at least 4 times within the family. We used ancestral state reconstructions to investigate the importance of several amino acid substitutions (Ile17Met, Ala64Ser, Asn70Ser, and Ser137Ala) previously shown to have evolved under positive selection that are correlated with blue spectral shifts. These reconstructions suggest that the Ala64Ser substitution has indeed occurred along the newly identified blueshifted L photopigment lineages. Substitutions at the other 3 sites may also be involved in the functional diversification of L photopigments. Our data strongly suggest that there are limits to the evolution of L photopigment spectral shifts among species with only one L opsin gene and that opsin gene duplication broadens the potential range of lambda(max) values.     

Light capture and pigment diversity in marine and freshwater cryptophytes

Phenotypic traits associated with light capture and phylogenetic relationships were characterized in 34 strains of diversely pigmented marine and freshwater cryptophytes. Nuclear SSU and partial LSU rDNA sequence data from 33 of these strains plus an additional 66 strains produced a concatenated rooted maximum likelihood tree that classified the strains into 7 distinct clades. Molecular and phenotypic data together support: (i) the reclassification of Cryptomonas irregularis NIES 698 to the genus Rhodomonas, (ii) revision of phycobiliprotein (PBP) diversity within the genus Hemiselmis to include cryptophyte phycocyanin (Cr‐PC) 569, (iii) the inclusion of previously unidentified strain CCMP 2293 into the genus Falcomonas, even though it contains cryptophyte phycoerythrin 545 (Cr‐PE 545), and (iv) the inclusion of previously unidentified strain CCMP 3175, which contains Cr‐PE 545, in a clade with PC‐containing Chroomonas species. A discriminant analysis‐based model of group membership correctly predicted 70.6% of the clades using three traits: PBP concentration · cell^?1, the wavelength of PBP maximal absorption, and habitat. Non‐PBP pigments (alloxanthin, chl‐a, chl‐c₂, α‐carotene) did not contribute significantly to group classification, indicating the potential plasticity of these pigments and the evolutionary conservation of the PBPs. Pigment data showed evidence of trade‐offs in investments in PBPs vs. chlorophylls (a +c₂).     

Ultrastructure and phototactic action spectra of two genera of cryptophyte flagellate algae,Cryptomonas and Chroomonas

Summary A comparative action spectroscopical study was made on phototaxis in two genera of cryptomonads (cryptophyte flagellate algae), namely,Cryptomonas (rostratiformis) andChroomonas (nordstedtii andcoeruled). The two genera differ in their characteristic phycobilin pigmentation and, among three species, onlyChroomonas coerulea possesses an eyespot. The two species with no eyespot,Cryptomonas rostratiformis andChroomonas nordstedtii, exhibited positive phototaxis, showing very similar action spectra characterized by a broad band in the region from 450 nm to 650 nm, with an action maximum at about 560 nm; these features are essentially the same as those observed previously forCryptomonas strain CR-1. InCryptomonas rostratiformis, a small peak was also found at 280 nm in the UV-B/C region.Chroomonas coerulea, with eyespot, did not exhibit distinct positive phototaxis in a wide spectral region at any given, even very low, light intensity, but exhibited negative phototaxis of spectral sensitivity maximal at 400–450 nm. These results indicate that the positive phototaxis ofCryptomonas (rostratiformis and CR-1) andChroomonas nordstedtii is mediated by the same, yet unidentified photoreceptor(s).Chroomonas nordstedtii, possessing no phycoerythrin absorbing at 545 nm, also exhibits positive phototaxis at ca. 560 nm, and this result disfavors the so far proposed possibility that the positive phototaxis of the cryptophytes may be mediated by phycobilin pigments. On the other hand, the spectral characteristics of negative phototaxis ofChroomonas coerulea can possibly be ascribed to the presence of an eyespot.     

Colour vision in the passeriform bird,Leiothrix lutea: correlation of visual pigment absorbance and oil droplet transmission with spectral sensitivity

The visual receptors in the retina of the passeriform bird Leiothrix lutea were examined microspectro-photometrically. The rods had a maximum absorbance close to 500 nm. Four spectrally different classes of single cone were identified with typical combinations of photopigments and oil droplets: a long-wave sensitive cone with a photopigment P568 and a droplet with a cut-off wavelength at 564 nm, a middle-wave sensitive cone with a P499 and a droplet with a cut-off at 506 nm, a short-wave sensitive cone with a P454 and a droplet with maximum absorbance below 410nm and an ultraviolet sensitive cone with a P355 and a transparent droplet. Double cones possessed a P568 in both the principal and accessory members. A pale droplet with variable absorbance (maximal at about 420 nm) was associated with the principal member whereas the ellipsoid region of the accessory member contained only low concentrations of carotenoid. The effective spectral sensitivities of the different cone classes were calculated from the characteristic combinations of oil droplets and photopigments and corrected for the absorbance of the ocular media. Comparison of these results with the behavioural spectral sensitivity function of Leiothrix lutea suggests that the increment threshold photopic spectral sensitivity of this avian species is mediated by the 4 single cone classes modified by neural opponent mechanisms.Abbreviations LWS long wave sensitive - MWS middle wave sensitive - SWS short wave sensitive (cones)     

Quantification of protein concentration by the Bradford method in the presence of pharmaceutical polymers

We investigated how the Bradford assay for measurements of protein released from a drug formulation may be affected by a concomitant release of a pharmaceutical polymer used to formulate the protein delivery device. The main result is that polymer-caused perturbations of the Coomassie dye absorbance at the Bradford monitoring wavelength (595 nm) can be identified and corrected by recording absorption spectra in the region of 350–850 mm. The pharmaceutical polymers Carbopol and chitosan illustrate two potential types of perturbations in the Bradford assay, whereas the third polymer, hydroxypropylmethylcellulose (HPMC), acts as a nonperturbing control. Carbopol increases the apparent absorbance at 595 nm because the polymer aggregates at the low pH of the Bradford protocol, causing a turbidity contribution that can be corrected quantitatively at 595 nm by measuring the sample absorbance at 850 nm outside the dye absorption band. Chitosan is a cationic polymer under Bradford conditions and interacts directly with the anionic Coomassie dye and perturbs its absorption spectrum, including 595 nm. In this case, the Bradford method remains useful if the polymer concentration is known but should be used with caution in release studies where the polymer concentration may vary and needs to be measured independently.     

Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus)

The potential for trichromacy in mammals, thought to be unique to primates, was recently discovered in two Australian marsupials. Whether the presence of three cone types, sensitive to short- (SWS), medium- (MWS) and long- (LWS) wavelengths, occurs across all marsupials remains unknown. Here, we have investigated the presence, distribution and spectral sensitivity of cone types in two further species, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus). Immunohistochemistry revealed that SWS cones in the quokka are concentrated in dorso-temporal retina, while in the quenda, two peaks were identified in naso-ventral and dorso-temporal retina. In both species, MWS/LWS cone spatial distributions matched those of retinal ganglion cells. Microspectrophotometry (MSP) confirmed that MWS and LWS cones are spectrally distinct, with mean wavelengths of maximum absorbance at 502 and 538 nm in the quokka, and at 509 and 551 nm, in the quenda. Although small SWS cone outer segments precluded MSP measurements, molecular analysis identified substitutions at key sites, accounting for a spectral shift from ultraviolet in the quenda to violet in the quokka. The presence of three cone types, along with previous findings in the fat-tailed dunnart and honey possum, suggests that three spectrally distinct cone types are a feature spanning the marsupials.     

Spectral tuning and the visual ecology of mantis shrimps

The compound eyes of mantis shrimps (stomatopod crustaceans) include an unparalleled diversity of visual pigments and spectral receptor classes in retinas of each species. We compared the visual pigment and spectral receptor classes of 12 species of gonodactyloid stomatopods from a variety of photic environments, from intertidal to deep water (> 50 m), to learn how spectral tuning in the different photoreceptor types is modified within different photic environments. Results show that receptors of the peripheral photoreceptors, those outside the midband which are responsible for standard visual tasks such as spatial vision and motion detection, reveal the well-known pattern of decreasing lambdamax with increasing depth. Receptors of midband rows 5 and 6, which are specialized for polarization vision, are similar in all species, having visual lambdamax-values near 500nm, independent of depth. Finally, the spectral receptors of midband rows 1 to 4 are tuned for maximum coverage of the spectrum of irradiance available in the habitat of each species. The quality of the visual worlds experienced by each species we studied must vary considerably, but all appear to exploit the full capabilities offered by their complex visual systems.     

Leaf spectral signatures differ in plant species colonizing habitats along a hydrological gradient

Aims We aimed at determining differences in the leaf spectral signatures of plant species groups growing in habitats along the hydrological gradient of an intermittent wetland and to define leaf traits that explain their variability. We want to contribute to the understanding of the causes for plant spectrum variability at leaf and community levels.Methods We measured leaf reflectance spectra (300–887nm) of representative plant species from different habitats and analyzed spectral differences among species groups. To explain leaf spectra variability within a group, we performed detailed analyses of leaf morphological and biochemical traits in selected species.Important findings The reflectance spectra of the different species groups differed most in the green, yellow and red spectral ranges. The reflectance spectra of submerged leaves of hydrophytes with simple structures were explained by their biochemical traits (carotenoids), while for more complex aerial leaves, morphological traits were more important. In submerged and natant leaves of amphiphytes, total mesophyll and spongy tissue thickness were the most important traits, and these explained 44% and 47%, respectively, of the spectrum variability of each plant group. In general, the redundancy analysis biplots show that samples of different plant species colonizing the same habitat form separate clusters and are related to the explanatory variables in different ways. The redundancy analysis biplots of helophytes and wet meadow species show clustering of graminoids and dicots into two distinct groups. Leaf encrustation (prickle hair properties and epidermis thickness) is important for graminoids, while leaf thickness and specific leaf area have more important roles in dicots. Our results show that knowledge of the species composition and leaf traits is necessary to interpret the reflectance spectra of such plant communities.