Flavonoids of Helianthus series Angustifolii

Leaf and ray flower flavonoids were investigated for the seven species of Helianthus series Angustifolii. Flavone aglycones occur in small glandular trichomes located on leaf undersurfaces of H. angustifolius, H. floridanus and H. simulans. Other species lacked both glandular trichomes and flavone aglycones. Flavonol glycosides occur in low concentrations in leaves of all species but were not characterized. Anthochlors (chalkones) occur in leaves of H. heterophyllus and H. longifolius. Ray flower flavonoids include anthochlor and flavonol glycosides and occur in the basal region of the ligule producing a band of UV A around the head. Anthochlors are the predominant ray flower flavonoids in H. angustifolius, H. heterophyllus and H. longifolius, whereas they are absent and quercetin 7-glucoside is present in H. carnosus and H. floridanus. Cladistic analysis of flavonoid and morphological characters indicates that evolution in the series has been a radiation from ancestral types rather than a linear sequence of progressively more derived species.     

Pollen advertisement: chemical contrasts between whole-flower and pollen odors

Odors of pollen and whole flowers were compared in taxonomically unrelated species that offer pollen as the only food reward to pollinators. Volatiles were collected using headspace adsorption and analyzed by gas chromatography and mass spectrometry. The odor of pollen was found to be chemically distinct from the total flower odor, and this pollen-odor distinctness varied among the three species. In Papaver rhoeas (Papaveraceae), the contrast between pollen and whole-flower odors was most subtle, with differences observed only in the proportions of individual volatiles (almost exclusively aliphatic hydrocarbons). In Filipendula vulgaris (Rosaceae), pollen volatiles were fewer than in the flowers (comprising mainly benzenoids and fatty-acid derivatives) and their relative proportions produced an odor dominated by 2-heptadecanone that contrasted strikingly with the flower odor dominated by 2-phenyl ethanol. In Lupinus polyphyllus (Fabaceae), the pollen odor contained fewer volatiles and in differing proportions than the flower fragrance (comprising almost exclusively isoprenoids). The findings add to earlier chemical evidence of odor contrasts between pollen and other flower parts in two other species. Drawing on information from pollination studies of these various species, it is suggested that pollen odor is used by pollen-foraging insects both to discriminate between plant species and to assess reward availability in individual flowers, and that it might in addition serve a protective function against destructive flower-feeding insects and pathogens.     

Comparative analysis of the volatiles from flowers and leaves of three Gentiana species

The volatiles from fresh flowers and leaves of Gentiana lutea L., Gentiana punctata L. (yellow Gentiana spp.) and Gentiana asclepiadea L. (Gentianaceae Juss.) were analyzed by GC/MS and 81 compounds identified. The samples studied showed differences in the volatile profiles of flowers and leaves among the species. In the flower-oils straight chain saturated aliphatic hydrocarbons were dominant along with low concentrations of branched saturated aliphatic hydrocarbons and alkylated benzenes. These compounds were not present in the flowers of G. lutea and G. punctata and in the leaves of G. lutea. The branched saturated aliphatic hydrocarbons were the main constituents of the leaf-oil from G. ascleapidea. Terpenes were found in all flower-oils and in the leaf oil from G. punctata. Some of the identified compounds might have allelopathic activity. The results obtained confirm the accepted taxonomical scheme of the genus Gentiana and are also in agreement with the evolutionary less advanced position of the yellow species of Gentiana.     

Anti-herbivore structures of Paulownia tomentosa: morphology, distribution, chemical constituents and changes during shoot and leaf development

Background and Aims: Recent studies have shown that small structures on plant surfacesserve ecological functions such as resistance against herbivores.The morphology, distribution, chemical composition and changesduring shoot and leaf development of such small structures wereexamined on Paulownia tomentosa. Methods: The morphology and distribution of the structures were studiedunder light microscopy, and their chemical composition was analysedusing thin-layer chromatography and high-performance liquidchromatography. To further investigate the function of thesestructures, several simple field experiments and observationswere also conducted. Key Results: Three types of small structures on P. tomentosa were investigated:bowl-shaped organs, glandular hairs and dendritic trichomes.The bowl-shaped organs were densely aggregated on the leavesnear flower buds and were determined to be extrafloral nectarines(EFNs) that secrete sugar and attract ants. Nectar productionof these organs was increased by artificial damage to the leaves,suggesting an anti-herbivore function through symbiosis withants. Glandular hairs were found on the surfaces of young and/orreproductive organs. Glandular hairs on leaves, stems and flowerssecreted mucilage containing glycerides and trapped small insects.Secretions from glandular hairs on flowers and immature fruitscontained flavonoids, which may provide protection against someherbivores. Yellow dendritic trichomes on the adaxial side ofleaves also contained flavonoids identical to those secretedby the glandular hairs on fruits and flowers. Three specialtypes of leaves, which differed from the standard leaves inshape, size and identity of small structures, developed nearyoung shoot tips or young flower buds. The density of smallstructures on these leaf types was higher than on standard leaves,suggesting that these leaf types may be specialized to protectyoung leaves or reproductive organs. Changes in the small structuresduring leaf development suggested that leaves of P. tomentosaare primarily protected by glandular hairs and dendritic trichomesat young stages and by the EFNs at mature stages. Conclusions: The results indicate that P. tomentosa protects young and/orreproductive organs from herbivores through the distributionand allocation of small structures, the nature of which dependson the developmental stage of leaves and shoots.     

Flavonoids of Helianthus series Microcephali

Ray flower and leaf flavonoids were investigated for the three species of Helianthus series Microcephali. Ray flowers of all species contain coreopsin, sulphurein, and quercetin 7-O-glucoside; those of H. microcephalus also contain quercetin 3-O-glucoside. A mixture of flavonoid aglycones, mostly methoxylated flavones, occurs in leaves of H. microcephalus, but not in H. glaucophyllus or H. laevigatus which also lack the glandular trichomes that in Helianthus are typically associated with flavonoid aglycones. The presence of compounds with the 6,8,4′ pattern of methoxylation in H. microcephalus suggests that the series is more similar in flavonoids to series Angustifolii than to series Corona-solis.     

铁皮石斛化学成分及其抗氧化活性研究

采用硫酸-苯酚法、AlCl^₃比色法、酸性染料比色法测定铁皮石斛(Dendrobium officinale)花、叶、茎中多糖、黄酮、生物碱含量，通过DPPH和ABTS清除实验评价铁皮石斛花、叶、茎的水提物和乙醇提取物的体外抗氧化活性。结果表明，铁皮石斛不同部位的多糖含量茎>花>叶，黄酮含量花>叶>茎，生物碱在各个部位分布均较少。其中茎的多糖含量可达23.92%，花中黄酮含量可达1.847%。抗氧化能力评价表明，铁皮石斛花水提物、茎醇提物、花醇提物的DPPH自由基清除能力相对较好，半效应浓度(EC₅₀)分别为410.4 μg·mL^-1、454.1 μg·mL^-1、573.2 μg·mL^-1；铁皮石斛茎醇提物、花醇提物、花水提物ABTS自由基清除能力相对较好，半效应浓度(EC₅₀)分别为61.1 μg·mL^-1、62.2 μg·mL^-1、103.0 μg·mL^-1。铁皮石斛花的提取物抗氧化活性整体优于叶和茎，醇提物抗氧化能力优于水提物。     

Comparison of the volatile components of some mango cultivars

Three cultivars of mango from Sri Lanka (Jaffna, Willard and Parrot) were analysed for their volatile aroma components. The total concentrations of volatiles obtained were ca 251, 422 and 628 μg per kg of fresh fruit, respectively. Terpenes were the main volatiles of all three cultivars, with monoterpene hydrocarbons contributing 50–63 % w/w of the total volatiles and sesquiterpene hydrocarbons 14–19 %. Whilst the major volatile of Jaffna mango was cis-β-ocimene (38 %), α-terpinolene was the major volatile of the other two cultivars (32 % and 35 %). Esters were produced by all cultivars (2–16 %), Jaffna yielding most, the majority being unsaturated (12 %). Willard mango gave particularly high levels of non-terpene hydrocarbons (19 %), including a range of six long-chain alkanes (8 %), not detected in the other cultivars.     

Chemical composition of Crepis foetida L. and C. rubra L. volatile constituents and evaluation of the in vitro anti-inflammatory activity of salicylaldehyde rich volatile fraction

The genus Crepis L. (Asteraceae) comprises more than 200 currently recognized species. Several studies have been conducted on non-volatile phytochemicals of Crepis spp., featuring mainly sesquiterpene lactones and phenolic derivatives. Nevertheless, no report has been made on assessing the volatile constituents of the genus. Therefore, the present study is the first report to the chemical composition of the volatile constituents of two odoriferous Crepis spp., namely C. foetida L. and C. rubra L. Flowers and stems with leaves volatiles were analysed separately by gas chromatography coupled with mass spectrometry. In total, 37 volatile compounds were detected. Salicylaldehyde, carvacrol and aliphatic hydrocarbons are the main components of both C. foetida fractions, however C. rubra flowers are characterized by the abundance of β-sitosterol and eicosanoic acid, while the stems-leaves volatiles revealed to be more complex with hydrocarbons as main constituents.In addition, we investigated the salicylaldehyde rich volatile fraction for its in vitro activity on TNF-α induced ICAM-1 expression.     

The flavonoids of Tanacetum parthenium and T. vulgare and their anti-inflammatory properties.

The lipophilic flavonoids in leaf and flower of Tanacetum parthenium and T. vulgaris have been compared. While those of T. parthenium are methyl ethers of the flavonols 6-hydroxykaempferol and quercetagetin, the surface flavonoids of T. vulgare are methyl ethers of the flavones scutellarein and 6-hydroxyluteolin. Apigenin and two flavone glucuronides are surprisingly present in glandular trichomes on the lower epidermis of the ray florets of T. parthenium. The opportunity has been taken to revise the structures of the four 6-hydroxyflavonol methyl ethers of T. parthenium based on NMR measurements. These are now shown to be uniformly 6- rather than 7-O-methylated. Tanetin, previously thought to be a new structure, is now formulated as the known 6-hydroxykaempferol 3,6,4'-trimethyl ether. The vacuolar flavonoids of both plants are dominated by the presence of apigenin and luteolin 7-glucuronides; nine other glycosides were present, including the uncommon 6-hydroxyluteolin 7-glucoside in T. vulgare. When the major flavonol and flavone methyl ethers of the two plants were tested pharmacologically, they variously inhibited the major pathways of arachidonate metabolism in leukocytes. There were significant differences in potency, with the tansy 6-hydroxyflavones less active than the feverfew 6-hydroxyflavonols as inhibitors of cyclo-oxygenase and 5-lipoxygenase.     

Insect odour perception: recognition of odour components by flower foraging moths

Odours emitted by flowers are complex blends of volatile compounds. These odours are learnt by flower-visiting insect species, improving their recognition of rewarding flowers and thus foraging efficiency. We investigated the flexibility of floral odour learning by testing whether adult moths recognize single compounds common to flowers on which they forage. Dual choice preference tests on Helicoverpa armigera moths allowed free flying moths to forage on one of three flower species; Argyranthemum frutescens (federation daisy), Cajanus cajan (pigeonpea) or Nicotiana tabacum (tobacco). Results showed that, (i) a benzenoid (phenylacetaldehyde) and a monoterpene (linalool) were subsequently recognized after visits to flowers that emitted these volatile constituents, (ii) in a preference test, other monoterpenes in the flowers' odour did not affect the moths' ability to recognize the monoterpene linalool and (iii) relative preferences for two volatiles changed after foraging experience on a single flower species that emitted both volatiles. The importance of using free flying insects and real flowers to understand the mechanisms involved in floral odour learning in nature are discussed in the context of our findings.     

Regulation of Floral Terpenoid Emission and Biosynthesis in Sweet Basil (<Emphasis Type="Italic">Ocimum basilicum</Emphasis>)

Past studies have focused on the composition of essential oil of Ocimum basilicum leaves, but data on composition and regulation of its aerial emissions, especially floral volatile emissions, are scarce. We studied the chemical profile, within-flower spatial distribution (sepals, petals, pistils with stamina, and pedicels), diurnal emission kinetics and effects of exogenous methyl jasmonate (MeJA) application on the emission of floral volatiles by dynamic headspace collection, and identification using gas chromatography-mass spectrometry (GC–MS) and proton-transfer reaction mass spectrometry. We observed more abundant floral emissions from flowers compared with leaves. Sepals were the main emitters of floral volatiles among the flower parts studied. The emissions of lipoxygenase compounds and monoterpenoids, but not sesquiterpene emissions, displayed a diurnal variation driven by light. Response to exogenous MeJA treatment of flowers consisted of a rapid stress response and a longer-term acclimation response. The initial response was associated with enhanced emissions of fatty acid derivatives, monoterpenoids, and sesquiterpenoids without variation of the composition of individual compounds. The longer-term response was associated with enhanced monoterpenoid and sesquiterpenoid emissions with profound changes in the emission spectrum. According to correlated patterns of terpenoid emission changes upon stress, highlighted by a hierarchical cluster analysis, candidate terpenoid synthases responsible for observed diversity and complexity of released terpenoid blends were postulated. We conclude that flower volatile emissions differ quantitatively and qualitatively from leaf emissions, and overall contribute importantly to O. basilicum flavor, especially under stress conditions.     

Plant Volatiles: Recent Advances and Future Perspectives

Volatile compounds act as a language that plants use for their communication and interaction with the surrounding environment. To date, a total of 1700 volatile compounds have been isolated from more than 90 plant families. These volatiles, released from leaves, flowers, and fruits into the atmosphere and from roots into the soil, defend plants against herbivores and pathogens or provide a reproductive advantage by attracting pollinators and seed dispersers. Plant volatiles constitute about 1% of plant secondary metabolites and are mainly represented by terpenoids, phenylpropanoids/benzenoids, fatty acid derivatives, and amino acid derivatives. In this review we focus on the functions of plant volatiles, their biosynthesis and regulation, and the metabolic engineering of the volatile spectrum, which results in plant defense improvement and changes of scent and aroma properties of flowers and fruits.     

Chemical composition and biological activity of the essential oils of Senecio aegyptius var. discoideus Boiss

The essential oil of Senecio aegyptius var. discoideus flowers, leaves, stems and roots were isolated by hydrodistillation. Analysis of the oils by capillary GLC and GLC-mass spectrometry were performed and 34 out of 37 compounds were identified. The main component was isolated and characterized as 1,10-epoxyfuranoeremophilane using a combination of GLC, GLC-MS, and NMR analyses. The oils of flowers, leaves and stems were rich in monoterpene hydrocarbons while the root oil mainly contains furanoeremophilanes. Flower and leaf volatile oils showed significant level of antifungal activity against C. albicans, moderate effect against Gram positive bacteria, however, it has weak activity against Gram negative bacteria. The isolated sesquiterpene (1,10-epoxyfuranoeremophilane) exhibited substantial inhibitory activity against Gram negative bacteria.     

Seasonal variation of responses to herbivory and volatile communication in sagebrush (<Emphasis Type="Italic">Artemisia tridentata</Emphasis>) (Asteraceae)

Plants can respond to insect herbivory in various ways to avoid reductions in fitness. However, the effect of herbivory on plant performance can vary depending on the seasonal timing of herbivory. We investigated the effects of the seasonal timing of herbivory on the performance of sagebrush (Artemisia tridentata). Sagebrush is known to induce systemic resistance by receiving volatiles emitted from clipped leaves of the same or neighboring plants, which is called volatile communication. Resistance to leaf herbivory is known to be induced most effectively after volatile communication in spring. We experimentally clipped 25 % of leaves of sagebrush in May when leaves were expanding, or in July when inflorescences were forming. We measured the growth and flower production of clipped plants and neighboring plants which were exposed to volatiles emitted from clipped plants. The treatment conducted in spring reduced the growth of clipped plants. This suggests that early season leaf herbivory is detrimental because it reduces the opportunities for resource acquisition after herbivory, resulting in strong induction of resistance in leaves. On the other hand, the late season treatment increased flower production in plants exposed to volatiles, which was caused mainly by the increase in the number of inflorescences. Because the late season treatment occurred when sagebrush produces inflorescences, sagebrush may respond to late herbivory by increasing compensation ability and/or resistance in inflorescences rather than in leaves. Our results suggest that sagebrush can change responses to herbivory and subsequent volatile communication seasonally and that the seasonal variation in responses may reduce the cost of induced resistance.     

Interspecific variation in floral fragrances within the genus Narcissus (Amaryllidaceae)

To improve our understanding of the floral biology, pollination, and systematics of the genus Narcissus, a comparative study was made of flower volatiles from nine species native to southern Spain using headspace collection and GC-MS analysis. The species fell into three fragrance types based on the identity of their major volatiles. In all but one species the fragrances consisted mainly of monoterpene isoprenoids mixed with benzenoids: in six species trans-ß-ocimene occurred in high proportions, in two others it was lacking; the last species had a fragrance dominated by fatty acid derivatives, mixed with terpenoids. Two of the species showed marked intraspecific variation in many of their volatiles. When the volatile data matrix of all species was subjected to cluster analyses and the resulting phenetic trees compared with currently recognized taxonomic groups, there was no congruence at the subgeneric level. However, there was considerable agreement at the sectional level, although in most sections we studied only a single species. This apparent agreement was stronger when the volatiles were analyzed according to shared biosynthetic pathways rather than treated individually, pointing to the higher value of using biosynthetic pathways for uncovering and confirming phenetic, and probable evolutionary, relationships among species. In terms of possible selective pressures from pollinators in shaping fragrance chemistry, available information on the pollination of our species suggested an association between fragrance and types of pollinators. Two pollinator-fragrance groups were apparent: (1) species pollinated by insects that include butterflies and moths displayed fragrances containing volatiles typical of moth-pollinated flowers, most particularly indole combined with high amounts of esters, and (2) species visited exclusively by insects other than butterflies and moths, especially by bees and flies, had fragrances lacking this combination of volatiles. Narcissus assoanus was unusual among our species in having both fragrance chemotypes. Future pollination studies of Narcissus in the field are needed to test the reliability and predictability of the proposed fragrance-pollinator associations.     

Volatiles and Nonvolatiles in Flourensia campestris Griseb. (Asteraceae), How Much Do Capitate Glandular Trichomes Matter?

The distribution and ultrastructure of capitate glandular trichomes (GTs) in Flourensia species (Asteraceae) have been recently elucidated, but their metabolic activity and potential biological function remain unexplored. Selective nonvolatile metabolites from isolated GTs were strikingly similar to those found on leaf surfaces. The phytotoxic allelochemical sesquiterpene (–)‐hamanasic acid A ((–)‐HAA) was the major constituent (ca. 40%) in GTs. Although GTs are quaternary ammonium compounds (QACs)‐accumulating species, glycine betaine was not found in GTs; it was only present in the leaf mesophyll. Two (–)‐HAA accompanying surface secreted products: compounds 4‐hydroxyacetophenone (piceol; 1 ) and 2‐hydroxy‐5‐methoxyacetophenone ( 2 ), which were isolated and fully characterized (GC/MS, NMR), were present in the volatiles found in GTs. The essential oils of fresh leaves revealed ca. 33% monoterpenes, 26% hydrocarbon‐ and 30% oxygenated sesquiterpenes, most of them related to cadinene and bisabolene derivatives. Present results suggest a main role of GTs in determining the volatile and nonvolatile composition of F. campestris leaves. Based on the known activities of the compounds identified, it can be suggested that GTs in F. campestris would play key ecological functions in plant‐pathogen and plant‐plant interactions. In addition, the strikingly high contribution of compounds derived from cadinene and bisabolene pathways, highlights the potential of this species as a source of high‐valued bioproducts.     

Temporal relationship between emitted and endogenous floral scent volatiles in summer‐ and winter‐blooming Jasminum species

Jasminum spp. is cultivated for their fragrant flowers used in essential oil production and cosmetic uses. An attempt was made to study the temporal variations in floral scent volatiles composition including emitted, free endogenous and glycosyl‐linked volatile compounds from two summer‐blooming species namely, Jasminum auriculatum and Jasminum grandiflorum as well as from two winter‐blooming species namely, Jasminum multiflorum and Jasminum malabaricum. The overall emitted volatile organic compounds (VOCs) were found to be highest when the matrix Porapak Q 80/100 was used with dichloromethane (DCM) as elution solvent. The floral volatile emission from bud to senescence exhibited nocturnal maxima pattern for both the summer‐blooming species. Both the winter‐blooming species emitted its highest concentration at noon. The free endogenous concentrations of all VOCs were low when corresponding emitted concentrations were high. Enzymatic treatment of petal extract revealed that several aromatic volatiles including aromatic alcohols and monoterpenols are synthesized and stored in the flowers as water‐soluble glycosides; these compounds were shown to accumulate in higher amounts in flowers at late bud stage. These findings indicate the utilization of the precursors, i.e. the volatile‐conjugates, through hydrolysis followed by their release as free‐volatiles at flower opening stage. The outcome as a whole suggests a linkage among the temporal pattern of emitted volatiles, free‐endogenous volatiles and glycoside‐bound volatile compounds in all above studied Jasminum spp. and provided an overview of their floral volatilome.     

Comparative analysis of leaf trichome structure and composition of epicuticular flavonoids in Finnish birch species

The morphology, ultrastructure, density and distribution of trichomes on leaves of Betula pendula, B. pubescens ssp. pubescens, B. pubescens ssp. czerepanovii and B. nana were examined by means of light, scanning and transmission electron microscopy. The composition of flavonoids in ethanolic leaf surface extracts was analysed by high pressure liquid chromatography. All taxa examined contained both glandular and non-glandular trichomes (short and/or long hairs) but differed from each other in trichome ultrastructure, density and location on the leaf. Leaves of B. pubescens were more hairy than those of B. pendula, but the latter species had a higher density of glandular trichomes. Of the two subspecies of B. pubescens, leaves of ssp. pubescens had more short hairs on the leaf surface and four times the density of glandular trichomes of leaves of ssp. czerepanovii, whereas, in the latter subspecies, short hairs occurred largely on leaf veins, as in B. nana. The glandular trichomes were peltate glands, consisting of medullar and cortical cells, which differed structurally. Cortical cells possessed numerous small, poorly developed plastids and small vacuoles, whereas medullar cells had several large plastids with well-developed thylakoid systems and fewer vacuoles. In B. pubescens subspecies, vacuoles of the glandular cells contained osmiophilic deposits, which were probably phenolic, whereas in B. pendula, vacuoles of glandular trichomes were characterized by the presence of numerous myelin-like membranes. The composition of epicuticular flavonoids also differed among species. The two subspecies of B. pubescens and B. nana shared the same 12 compounds, but five of these occurred only in trace amounts in B. nana. Leaf surface extracts of B. pendula contained just six flavonoids, three of which occurred only in this species. In summary, the structure, density and distribution of leaf trichomes and the composition of epicuticular flavonoids represent good taxonomic markers for Finnish birch species.     

Analysis of the volatile components of five Turkish Rhododendron species by headspace solid-phase microextraction and GC-MS (HS-SPME-GC-MS)

Volatile constituents of various solvent extracts (n-hexane, CH2Cl2, H2O) of 15 different organs (leaves, flowers, fruits) of five Rhododendron species (Ericaceae) growing in Turkey were trapped with headspace solid-phase microextraction (HS-SPME) technique and analyzed by GC-MS. A total of 200 compounds were detected and identified from organic extracts, while the water extracts contained only traces of few volatiles. The CH2Cl2 extract of the R. luteum flowers was found to exhibit the most diverse composition: 34 compounds were identified, with benzyl alcohol (16.6%), limonene (14.6%) and p-cymene (8.4%) being the major compounds. The CH2Cl2-solubles of R. x sochadzeae leaves contained only phenyl ethyl alcohol. This study indicated appreciable intra-specific variations in volatile compositions within the genus. Different anatomical parts also showed altered volatile profiles. This is the first application of HS-SPME-GC-MS on the volatiles of Rhododendron species.     

Seasonal variation of monoterpene emission from Malus domestica and Prunus avium

Emission rates of monoterpenes released by apple (Malus domestica Borkh) and cherry (Prunus avium L.) were estimated at different phenological stages. These measurements employed a dynamic flow-through Teflon chamber, sample collection onto cartridges filled with graphitized carbon and thermal desorption gas chromatography-mass spectrometry (GC-MS) for identification and quantification of the emitted volatiles. At full bloom the release of monoterpene hydrocarbons from cherry flowers was 1213 ng g(-1) dry weight (DW) h(-1), exceeding by approximately three-fold the emission rate of apple flowers (366 ng g(-1) DW h(-1)). Observed seasonal variations in biogenic volatile organic compound (VOC) emissions ranged over several order of magnitudes. At fruit-set and ripening stages, in fact, the hydrocarbon emission dramatically decreased reaching the lowest values at harvest time when leaves were fully mature (3-9 ng g(-1) DW h(-1)). Wide diversity in the composition of compounds from the species studied was also recorded. At blooming, linalool contributed significantly to the monoterpene emission from apple (94% of the emitted carbon) while alpha-pinene and camphene represented on average more than 60% of the total emitted volatiles from cherry flowers. Among the monoterpenes identified in flowers, alpha-pinene, camphene and limonene were also found in the foliage emission of both species. Fruit trees are relevant monoterpene emitters only at blooming and thus for a short period of the vegetative cycle. When leaves are fully developed, the carbon loss due to monoterpene emissions related to the photosynthetically carbon gain is negligible.