Leaf flavonoid content in Quercus ilex L. resprouts and its seasonal variation

Here, we provide the first report on flavonoid content in holm oak (Quercus ilex L.) leaves, analyzed by HPLC–MS/MS. Flavanols and flavonols were the predominant groups, although proanthocyanidins and many soluble tannins had a relevant presence in all leaf samples. Seasonal variation of flavonoids was determined in extracts from Q. ilex leaves during resprouting after a forest fire in two Mediterranean forests. Similar seasonal trends were observed over 2 years during the two main stress seasons (winter and summer). The most abundant flavonoid was the flavanol epicatechin, which showed similar values during the two seasons. Hexosides of the flavonols, quercetin, kaempferol and rhamnetin showed considerably higher content in winter, especially at the lowest temperatures. These variations in both forests are discussed on the basis of the chlorophyll fluorescence results obtained. Anthocyanins were found practically absent in mature leaves. Nutrient or water availability differences between sites or seasons were not related to changes in leaf flavonol-hexoside content.     

The Dynamics of Leaf Growth and Photosynthetic Capacity in Capsicum frutescens L.

In Capsicum frutescens L. cv. California Wonder the specificleaf weight (dry weight per unit laminar area) at leaf unfoldingis three times higher in the eighth leaf than in the first leafproduced. Intermediate leaves exhibit a trend between the twoThe change in specific leaf weight during laminar expansionis greatest in leaf 1 and least (sometimes zero) in leaf 8.Large changes in specific leaf weight during laminar expansionare associated with a large degree of palisade cell expansion,while leaves showing smaller rates of change have less palisadecell expansion but cell division is more evident. At leaf unfoldingthe fraction I protein content per unit laminar area is higherin upper than in lower leaves. Ribulose diphosphate carboxylaseactivity per unit laminar area and ¹⁴CO₂ fixation per unit laminararea have a similar pattern of development in all leaves andshow no correlation with the changes in specific leaf weight.The peak of activity in all leaves occurs when the laminar areais 10 cm². These results are compared with previous data onlaminar expansion and are seen as in accord with current ideason leaf growth.     

Experimental Studies of the Factors Controlling Transpiration: II. THE RELATION BETWEEN TRANSPIRATION RATE AND LEAF WATER CONTENT

Data are presented which show, when stomatal control is eliminated,that wheat leaves may lose 5–6 per cent. and Pelargoniumleaves 10–12 per cent. of their water without any reductionin the transpiration rate. Experiments in which Pelargonium and wheat leaves, with stomatalcontrol present, were submitted to cycles of changing watercontent also failed to establish any direct relation betweentranspiration rate and leaf water content. It is concluded that leaf water content over the range of 70–100per cent. of that present in the turgid state has no significanteffect in determining the rate of water loss from leaves. A repetition of Knight's experiment showed that stomata openedin still air and closed in moving air. This was not recordedby Knight, who used a porometer cup permanently attached tothe leaf. It is concluded that the higher transpiration raterecorded by Knight after a period of still air was due to widerstomatal aperture and not to the higher leaf water content assuggested by him.     

温度和土壤水分对银杏叶黄酮类化合物积累的影响

以2年生银杏实生苗为试材,在人工气候室内采用土培盆栽试验方法,研究了温度和土壤水分对银杏叶黄酮类化合物积累的影响.试验设置土壤含水量(W)和温度(T)各3个梯度,W₁、W₂、W₃分别为田间持水量的55%～60%、40%～45%、30%～35%;T₁、T₂、T₃白天和夜间的温度分别为15/5 ℃、25/15 ℃、35/25 ℃.结果表明: T₁温度条件下,各土壤水分处理的银杏叶中的槲皮素、山奈酚、异鼠李素和总黄酮含量普遍高于T₂和T₃,而土壤水分对银杏叶中各种黄酮类化合物积累的影响不显著;银杏叶中黄酮类化合物以山奈酚含量最高,其次为槲皮素和异鼠李素;T₃温度下银杏单株总黄酮产量普遍高于T₂和T₁.在收获前适当采取土壤覆盖和灌水等措施降低种植园的温度,有利于提高银杏叶中黄酮的含量,增加单位面积黄酮的产量.     

Changes of Starch and Sorbitol in Leaves Before and After Removal of Fruits from Peach Trees

Changes in contents of nonstructural carbohydrates in leaves,as well as some characteristics of leaves before and after fruitremoval, were investigated in potted peach (Prunus persica L.)trees. Leaf area and dry mass per unit leaf area (SLW) at thefruit-maturation stage decreased with increasing numbers ofpeaches per tree, whereas the chlorophyll content per unit areain leaves of fruiting trees increased. The chlorophyll contentdecreased more rapidly upon removal of fruit than that in leavesof fruiting trees. The starch content per unit dry mass in leavesof fruiting trees at the fruit-maturation stage was lower thanthat in leaves of non-fruiting trees. Starch accumulated significantlyin leaves within 1 d of removal of fruit during the fruit-maturationstage and continued to increase thereafter. The accumulationof starch after removal of fruit occurred more rapidly thanthe decrease in chlorophyll content. Reducing and non-reducingsugars (total sugars) per unit dry mass in the leaves were higherin fruiting trees than in non-fruiting trees. After fruit removal,the total sugar content of leaves increased temporarily andthen gradually decreased. The sorbitol content per unit freshmass in leaves of fruiting trees during the fruit-maturationstage was slightly higher than that in leaves of non-fruitingtrees. One day after removal of fruit, the sorbitol contentincreased in parallel with the accumulation of starch and remainedhigh. The sucrose content of leaves did not change markedlyupon removal of fruit. Prunus persica L.; peach leaves; nonstructural carbohydrate; starch and sorbitol; fruit removal     

Senescence in Leaves of Acer pseudoplatanus L. and Parthenocissus tricuspidata Planch: 1. Changes in Some Leaf Constituents during Maturity and Senescence

Data are recorded of the changes in chlorophylls, carotene,sugar, shikimic acid, and anthocyanin in leaves of sycamore(Acer pseudoplatanus L.) and Virginia creeper (Parthenocissustricuspidata Planch.) during leaf maturity and senescence. InParthenocissus the losses of chlorophylls, carotene, sugar,and shikimic acid during senescence were closely correlated,and were inversely related to the accumulation of anthocyanin.The losses of chlorophylls, carotene, and sugar by Acer leaveswere also closely correlated. No evidence was found to supportthe suggestion that anthocyanin formation was caused by accumulationof sugar during senescence, but marked differences in shikimicacid content were found between leaves of Acer, which did notform anthocyanin, and Parthenocissus. which did. It is suggestedthat autumn senescence of these leaves involves the rapid senescenceof an increasing proportion of the leaf tissue during a periodof 80 days, and that measurements of the content of constituentsgive an estimate of the proportion of the leaf tissue whichhas senesced.     

Control of Ribulose-1,5-diphosphate Carboxylase Activity During Expansion of Leaves of Capsicum frutescens L.

The activity of ribulose-1,5-diphosphate carboxylase per unitlaminar area increases rapidly during early stages of leaf expansionin Capsicum frutescens L. cv. California Wonder. This is followedby a decrease to a level that is constant until expansion stops. A previous suggestion that the expansion of younger leaves inthe same phyllotactic sector controlled the decrease in enzymeactivity in older expanding leaves has not been verified byexperiments involving the selective excision of leaves and cotyledons.Decrease in enzyme activity was accompanied by a fall in FractionI protein content but another chloroplastic enzyme, -aminolevulinicacid dehydrase, did not exhibit a decrease in activity. Intra-chloroplasticmechanisms, rather than the influence of other plant organs,are suggested as controlling ribulose-1,5-diphosphate carboxylaseactivity during later stages of leaf expansion.     

Positive and Negative Messages from Roots Induce Foliar Desiccation and Stomatal Closure in Flooded Pea Plants

Flooding the soil for 5–7 d caused partial desiccationin leaves of pea plants (Pisum sativum. L. cv. ‘Sprite’).The injury was associated with anaerobiosis in the soil, a largeincrease in the permeability of leaf tissue to electrolytesand other substances, a low leaf water content and an increasedwater saturation deficit (WSD). Desiccating leaves also lackedthe capacity to rehydrate in humid atmospheres, a disabilityexpressed as a water resaturation deficit (WRSD). This irreversibleinjury was preceded during the first 4–5 d of floodingby closure of stomata within 24 h, decreased transpiration,an unusually large leaf water content and small WSD. Leaf waterpotentials were higher than those in well-drained controls.Also, there was no appreciable WRSD. Leaflets detached fromflooded plants during this early phase retained their watermore effectively than those from controls when left exposedto the atmosphere for 5 min. Stomatal closure and the associated increase in leaf hydrationcould be simulated by excising leaves and incubating them withtheir petioles in open vials of water. Thus, such changes inflooded plants possibly represented a response to a deficiencyin the supply of substances that would usually be transportedfrom roots to leaves in healthy plants (negative message). Ionleakage and the associated loss of leaf hydration that occurswhen flooding is extended for more than 5 d could not be simulatedby isolating the leaves from the roots. Appearance of this symptomdepended on leaves remaining attached to flooded root systems,implying that the damage is caused by injurious substances passingupwards (positive message). Both ethylene and ethanol have beeneliminated as likely causes, but flooding increased phosphorusin the leaves to concentrations that may be toxic. Key words: Pisum sativum, Flooding, Foliar desiccation, Stomata, Ethylene     

Relationship between Leaf Structure and Gas Exchange in Wheat Leaves at Different Insertion Levels

Net photosynthesis rate (P_n), stomatal conductance to CO₂ andresidual conductance to CO₂ were measured in the last six leaves(the sixth or flag leaf and the preceding five leaves) of Triticumaestivum L. cv. Kolibri plants grown in Mediterranean conditions.Recently fully expanded leaves of well-watered plants were alwaysused. Measurements were made at saturating photosynthetic photonflux density, and at ambient CO₂ and O₂ levels. The specificleaf area, total organic nitrogen content, some anatomical characteristics,and other parameters, were measured on the same leaves usedfor gas exchange experiments. A progressive xeromorphic adaptation in the leaf structure wasobserved with increasing leaf insertion levels. Furthermore,mesophyll cell volume per unit leaf area (V_mes/A) decreasedby 52·6% from the first leaf to the flag leaf. Mesophyllcell area per unit leaf area also decreased, but only by 24·5%.However, nitrogen content per unit mesophyll cell volume increasedby 50·6% from the first leaf to the flag leaf. This increasecould be associated to an observed higher number of chloroplastcross-sections per mm² of mesophyll cell cross-sectional areain the flag leaf: values of 23000 in the first leaf and 48000in the flag leaf were obtained. P_n per unit leaf area remainedfairly constant at the different insertion levels: values of33·83±0·93 mg dm^–2 h^–1 and32·32±1·61 mg dm^–2 h^–1 wereobtained for the first leaf and the flag leaf, respectively.Residual conductance, however, decreased by 18·2% fromthe first leaf to the flag leaf. Stomatal conductance increasedby 41·7%. The steadiness in P_n per unit leaf area across the leaf insertionlevels could be mainly accounted for by an opposing effect betweena decrease in V_mes/A and a more closely packed arrangement ofphotosynthetic apparatus. Adaptative significance of structuralchanges with increasing leaf insertion levels and the steadinessin P_n per unit leaf area was studied. Key words: Photosynthesis, structure, wheat     

Partial Purification and Some Properties of Flavonol 3-O-Glycosyltransferases from Seedlings of Vigna mungo, with Special Reference to the Formation of Kaempferol 3-O-Galactoside and 3-O-Glucoside

A novel enzyme, UDP-D-galactose:flavonol 3-O-galactosyltransferase(F3GaT), catalyzing the transfer of D-galactose from UDP-D-galactoseto the 3 position of 5,7,4'-trihydroxyflavonol (kaempferol),was detected in and purified about 404-fold from seedlings ofVigna mungo by precipitation with ammonium sulfate, chromatographyon Sephadex G-100 and chromatofocusing. The enzyme was separatedby this procedure from a coexisting UDP-D-glucose:flavonol 3-O-glucosyltransferase(F3GT), which was simultaneously purified about 189-fold. F3GaTwas isolated as a soluble enzyme with pH optima of 8.0 in imidazole-HClbuffer and 7.5 in histidine-HCl buffer. F3GT had the same pHoptima. The M_r of both F3GaT and F3GT, which had isoelectricpoints of 5.1 and 6.1, respectively, was estimated by elutionfrom a column of Sephadex G-100 to be about 43,000. The activitiesof F3GaT and F3GT were stimulated by 14 mM 2-mercaptoethanoland strongly inhibited by 1 mM Cu²⁺, 1 mM Zn²⁺, and variousreagents that react with sulfhydryl groups. Among various possiblesubstrates for F3GaT that were tested, kaempferol, isorhamnetinand quercetin were the best. The K_m values for kaempferol andUDP-D-galactose were determined to be 0.40 µM and 125µM, respectively. Similarly, F3GT had low K_m values of0.69 µM for kaempferol and 1.67 mM for UDP-D-glucose.F3GaT and F3GT mediated the transfer of galactose and glucose,respectively, to the 3-hydroxyl groups exclusively of kaempferol,isorhamnetin and quercetin. Rhamnetin also functioned as a galactosylacceptor though less efficiently. (Received October 12, 1992; )     

Leaf and Tiller Production of Prairie Grass (Bromus willdenowii Kunth) and Two Ryegrass (Lolium) Species

A detailed morphological study of three prairie grass cultivars(Bromus willdenowii Kunth) was conducted under ‘vegetative’and ‘reproductive’ growth conditions (short andlong photoperiods) and at different temperatures. Perennialryegrass (Lolium perenne L.) and Westerwolds ryegrass (Loliummuhiflorum Lam.) were compared during vegetative growth. Prairie grass had higher leaf appearance rates (leaves per tillerper day) and lower site filling (tillers per tiller per leafappearance interval) than the ryegrass species. Tillering rates(tillers per tiller per day) were also lower, except under vegetativeconditions at 4C. Low tiller number in prairie grass was notdue to lack of tiller sites but a result of poor filling ofthese sites. Lower site filling occurred because of increaseddelays in appearance of the youngest axillary tiller and lackof axillary tillers emerging from basal tiller buds. In prairiegrass, no tillers came from coleoptile buds while only occasionallydid prophyll buds develop tillers. Low tiller number in prairiegrass was compensated for by greater tiller weight. Prairiegrass had more live leaves per tiller, greater area per leafand a high leaf area per plant. Considerable variation between cultivars was found in prairiegrass. The cultivar ‘Bellegarde’ had high leaf appearance,large leaves and rapid reproductive development, but had lowlevels of site filling, tillering rate, final tiller numberand herbage quality during reproductive growth. ‘Primabel’tended to have the opposite levels for these parameters, while‘Grasslands Matua’ was intermediate and possiblyprovided the best balance of all plant parameters. prairie grass, Bromus willdenowii Kunth, perennial ryegrass, Lolium perenne L., Westerwolds ryegrass, Lolium multiflorum Lam., temperature, photoperiod, leaf appearance, leaf area, tillering, site filling, tillering sites, yield     

Leaf Growth in Dactylis glomerate following Defoliation

Defoliation to a height of 2.5 cm considerably reduced the increasein leaf area in young Dactylis glomerata (cocksfoot) plantscompared with that of intact plants, the reduction in the rateof appearance of new leaves being relatively greater than thereduction in expansion of existing leaves. The growth of thoseexpanding leaves which were cut during defoliation accountedfor 94 per cent of the total increase in leaf area during thefirst four days after defoliation. In such a leaf, expandingcells were confined to a basal section which was well belowthe ligule of the enclosing fully expanded leaf. There was a positive relationship between rate of leaf expansionand total soluble carbohydrate content of the stubble when thecarbohydrate content was varied by placing the plants in thedark, but not when it was varied by defoliation and subsequentgrowth. These and other results suggest that the concentrationof soluble carbohydrate in the bases of expanding leaves wasa factor controlling leaf expansion following defoliation, andthat the concentration in any one leaf depended on the photosyntheticcontribution from its exposed portion. When the external nutrient supply was high, removal of the laminaeof fully expanded leaves, which comprised about two-thirds ofthe total leaf area, did not reduce leaf expansion. When thenutrient status was low, these leaves were of primary importance,presumably because of their role as a source of labile nutrients.     

Identification of a Water-soluble Fungal Inhibitor in the Leaves of Acer platanoides L.

It was confirmed that the leaves of Acer platanoides containan antifungal inhibitory substance. Low concentrations of sterilecold water extracts inhibited the germination of the sporesof Cladosporium herbarum (three isolates), Cladosporium sphaerospermumand Cylindrocarbon radiclcola. In the concentration range 0·06–0·125per cent (w/v) of leaf material the inhibitory response wasdemonstrated to increase linearly as the concentration of leafmaterial increased logarithmically. Inhibitory activity wasfound in leaf samples collected during a period from July toOctober but activity had disappeared from leaves collected inthe following January. The inhibitory activity was located intwo components of the water extract by bioassay tests followingether extraction and separation by chromatography. One of theactive components has been identified as gallic acid by gaschromatography. Gallic acid has also been detected in dew collectedfrom leaf surfaces where it is suggested that it may play animportant part in the colonization of the leaves by fungi.     

Quercetin,Kaempferol and Isorhamnetin in Elaeagnus pungens Thunb. Leaf: Pharmacological Activities and Quantitative Determination Studies

Elaeagnus pungens leaf was documented to be very effective to treat asthma and chronic bronchitis both as traditional Chinese medicine and minority traditional medicine; yet the actual effective components still remain unknown. This work is to investigate the anti‐inflammatory, antalgic and antitussive activities of E. pungens leaf, quercetin and kaempferol, and their contents in E. pungens leaf. Pharmacological experiments showed that they could considerably reduce ear‐swelling of mouse and relieve writhing reaction of mouse; they could also prevent mouse from coughing significantly. These findings suggested that quercetin and kaempferol are major effective components treating asthma and chronic bronchitis. Quantitative analysis results indicated that the levels of quercetin, kaempferol and isorhamnetin varied greatly in different species of Elaeagnus and in different plant parts: E. pungens leaf is more similar to Elaeagnus umbellate leaf chemically; quercetin level is exceptionally high in Elaeagnus oldhami leaf; E. pungens leaf is a better medical part for treating asthma and chronic bronchitis in comparison with other parts.     

Measuring the RGR of Individual Grass Plants

Vegetative growth of grasses was analysed by dry mass increaseof growing leaves.Holcus lanatuswas grown in a controlled environmentand leaf extension rates of leaf numbers 5–10 of the maintiller were monitored daily. Leaf appearance and leaf extensionrates (LER) of leaves 5–7 enabled the prediction of thefinal length and dry mass of leaf 8 during its growth. A linearincrease of leaf mass per unit leaf length (LML) of leaf 8 wasobserved during growth. After harvest the daily increase indry mass of growing leaves was calculated from the LER and correspondingincrease in LML. The relative growth rate (RGR) of the maintiller showed day-to-day fluctuations and was gradually reducedby 50% over a 16-d period. The RGR of the shoot was maintainedby tillering. The RGR of a single (grass) plant can be calculatedfrom four parameters only: LER, LML, leaf appearance and tillering.Variation of RGR over a period can be reconstructed after harvestand the impact of these four parameters on RGR can be established.Copyright1998 Annals of Botany Company. Relative growth rate, grass, leaf growth,Holcus lanatus.     

Polyphenols of Rosa L. leaves extracts and their radical scavenging activity

Antioxidant potential of Rosa L. leaves methanolic extracts was evaluated in vitro using a spectrophotometric method based on measuring the radical scavenging effect on 2,2-di-phenyl-1-picrylhydrazyl (DPPH) radicals. The contents of ellagic acid, quercetin and kaempferol in the extracts from leaves of seventeen rose species were determined using SPE-RP-HPLC methods. Additionally, total phenolic content was determined spectrophotometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). Remarkable high antioxidant activity and high total phenolic content (5.7% < GAE < 15.2%), large ellagic acid (EA) content from 9.37 to 19.42 mg/g of dry weight, a quercetin content ranging from 3.68 to 15.81 mg/g of dry weight and kaempferol content from 1.25 to 9.41mg/g of dry weight were found in rose leaves. Significant correlation between EA (r(2) = 0.6131), quercetin (r(2) = 0.5158), total phenolic content (r(2)= 0.8485) and antioxidant activity was observed. Basing on the studies conducted one may assume that the extracts of rose leaves are a rich source of natural antioxidants and could be used to prevent free-radical-induced deleterious effects.     

Changes in Chlorophyll Content and Organization During Senescence of the Primary Leaves of Phaseolus vulgaris L. in Relation to Photosynthetic Electron Transport

A large decrease was observed in the chlorophyll content ofthe primary leaves of Phaseolus vulgaris during senescence.Chloroplasts isolated from mature and senescent leaves gavevery similar light saturation curves for electron transportreactions involving either PS I or PS II, indicating that theaverage number of chlorophyll molecules associated with eachreaction centre did not change during senescence. It is concludedthat the reaction centres ceased to function at the same timeas, or perhaps before, their antenna chlorophylls were lostfrom the thylakoid membrane, and that the percentage decreasein the number of functional reaction centres per leaf was atleast as great as the percentage decrease in the leaf chlorophyllcontent. The chlorophyll-protein composition of thylakoid membrane preparationswas examined by electrophoresis of samples treated with sodiumdodecyl sulphate. In older leaves a smaller proportion of thechlorophyll applied to polyacrylamide gels was associated withthe P700- chlorophyll a-protein complex. There was also a declinein emission at 734 nm in the 77 °K fluorescence spectrumof intact leaf tissue during senescence. These results indicatethat older leaves contained a smaller proportion of chlorophyllsassociated with PS I, and this is consistent with the decreaseobserved in the leaf chlorophyll a/b ratio during senescence.The effect of these changes in chlorophyll content on the capacityof the chloroplast to carry out photosynthetic electron transportis discussed.     

Purification and Identification of Flavonoids from the Yellow Green Cocoon Shell (Sasamayu) of the Silkworm,Bombyx mori

Three quercetin glycosides, quercetin 5-O-β-D-glucoside, quercetin 7-O-β-D-glucoside, and quercetin 4′-O-β-D-glucoside, and two kaempferol glycosides, kaempferol 5-O-β-D-glucoside and kaempferol 7-O-β-D-glucoside, along with their aglycones, quercetin and kaempferol, were isolated from an ethanolic extract of Sasamayu cocoon shells. The chemical structures were characterized by chemical and spectroscopic methods including UV spectrometry and HPLC-ESI-MS. The five flavonol glycosides of the shell are different structurally from those of the leaves of mulberry (Morus alba). It was suggested that potent antioxidative activity in the cocoon is mainly due to flavonoid compounds since free radical scavenging activity was found in the cocoon flavonoids identified here.     

Leaf Characteristics and Net Gas Exchange of Diploid and Autotetraploid Citrus

The effect of tetraploidy on leaf characteristics and net gasexchange was studied in diploid (2x ) and autotetraploid (4x) ‘Valencia’ sweet orange (Citrus sinensis (L.)Osb.) and ‘Femminello’ lemon (Citrus limon (L.)Burm. f.) leaves. Comparisons between ploidy levels were madeunder high irradiance (I) in a growth chamber or low total Iin a glasshouse. Tetraploids of both species had thicker leaves,larger mesophyll cell volume and lower light transmittance thandiploids regardless of growth I. Mesophyll surface area perunit leaf area of 2x leaves was 5–15% greater than on4x leaves. Leaf thickness and mesophyll cell volume were greaterin high I leaves than low I leaves. In high I, average leafarea was similar for 2x and 4x leaves, whereas in low I it was30% greater in 4x than in 2x leaves. Nitrogen and chlorophyllconcentration per cell increased with ploidy level in both growthconditions. The ratio of chlorophyll a:b was 25% greater in2x than in 4x leaves. When net CO₂assimilation rate (A_CO2) wasbased on leaf area, 4x orange leaves had 24–35% lowerA_CO2than their diploids. There were no significant differencesin A_CO2between 2x and 4x orange or lemon leaves when expressedon a per cell basis. Overall, lower A_CO2per unit leaf area oftetraploids was related to increase in leaf thickness, largermesophyll cell volume, the decrease in mesophyll area exposedto internal air spaces, and the lower ratio between cell surfaceto cell volume. Such changes probably increased the resistanceto CO₂diffusion to the site of carboyxlation in the chloroplasts. Cell volume; chlorophyll; irradiance; leaf thickness; nitrogen; photosynthesis; ploidy; Citrus limon ; C. sinensis ; ‘Valencia’ sweet orange; ‘Femminello’ lemon     

Polyphenolics in <Emphasis Type="Italic">Rhizophora mangle</Emphasis> L. leaves and their changes during leaf development and senescence

The chemical defenses in Rhizophora mangle L. are largely carbon based. The family has long been exploited for the high proanthocyanidin (condensed tannin) content of its wood, bark and leaves. In this paper, we quantify the overall pools of plant phenolics in R. mangle leaves, identify the major constituents of these pools and document their changes during leaf maturation and senescence. Overall, polyphenolics account for approximately 23% of the total leaf dry weight. The leaves contain at least seven flavonoid glycosides, five of them based on quercetin. Additional minor constituents are myricetin and kaempferol diglucosides. The aglycone, quercetin, was found only in senescing leaves. Also during senescence, a new compound, 5,4-dimethoxy-7,3,5-trihydroxyflavone, appeared. The flavonoids were accompanied by a complex mixture of condensed tannins based mainly on (+)-catechin and (–)-epicatechin with A-type and B-type linkages; this pool is also distinguished by having previously unreported, high contributions of (+)-catechin and (–)-epicatechin glycosides. During senescence, but prior to leaf abscission, the polyphenolic pools become simplified: flavonol glycosides and low oligomeric tannins largely disappear, leaving only the largest tannin polymers. The ecological and physiological significance of these compounds as they appear in R. mangle is discussed.