Structural features of an arabinogalactan gum exudates from Spondias dulsis (Anacardiaceae)

The tree Spondias dulcis, located in Venezuela, exudes a light-brown gum. The polysaccharide, isolated from the original gum, contains galactose, arabinose, mannose, rhamnose, glucuronic acid, and its 4-O-methyl derivative. Application of chemical methods, in combination with 1D and 2D NMR spectroscopy afforded interesting structural features of the gum polysaccharide. The unequivocal presence of rhamnose in the polymer structure was confirmed by chemical and spectral data [1H (1.03 ppm); 13C (16.92 ppm)]. Also confirmed was the existence of 3-O- and 6-O-substitutes galactose residues by the spectral data correlations observed in Heteronuclear Multiple Quantum Coherence (HMQC) and Heteronuclear Multiple Bond Correlation (HMBC). Also observed were unequivocal resonances for beta-D-glucuronic acid and its 4-O-methyl derivative, and the presence of 3-O-alpha-L-arabinofuranose and 3-O-beta-L-arabinopyranose residues.     

Domestication and the distribution of genetic variation in wild and cultivated populations of the Mesoamerican fruit tree Spondias purpurea L. (Anacardiaceae)

Domestication occurs as humans select and cultivate wild plants in agricultural habitats. The amount and structure of variation in contemporary cultivated populations has been shaped, in part, by how genetic material was transferred from one cultivated generation to the next. In some cultivated tree species, domestication involved a shift from sexually reproducing wild populations to vegetatively propagated cultivated populations; however, little is known about how domestication has impacted variation in these species. We employed AFLP data to explore the amount, structure, and distribution of variation in clonally propagated domesticated populations and sexually reproducing wild populations of the Neotropical fruit tree, Spondias purpurea (Anacardiaceae). Cultivated populations from three different agricultural habitats were included: living fences, backyards, and orchards. AFLP data were analysed using measures of genetic diversity (% polymorphic loci, Shannon's diversity index, Nei's gene diversity, panmictic heterozygosity), population structure (F(ST) analogues), and principal components analyses. Levels of genetic variation in cultivated S. purpurea populations are significantly less than variation found in wild populations, although the amount of diversity varies in different agricultural habitats. Cultivated populations have a greater proportion of their genetic variability distributed among populations than wild populations. The genetic structure of backyard populations resembles that of wild populations, but living fence and orchard populations have 1/3 more variability distributed among populations, most likely a reflection of relative levels of vegetative reproduction. Finally, these results suggest that S. purpurea was domesticated in two distinct regions within Mesoamerica.     

Leaf anatomy of Gluta (L.) Ding Hou (Anacardiaceae)

An anatomical study of the leaves of 21 species of Gluta (L.) Ding Hou (Anacardiaceae) reveals two major groups of species which reflect the original groups of Gluta L. and Melanorrhoea Wall., and a smaller group showing intermediate, or an admixture of, characters. The anatomical characters found to be of most use in this respect are: stomatal outline in surface view; stomatal density; glandular trichomes present/absent; glandular trichome body raised/sunken; cuticle striate/not striate; midrib dimensions as seen in transverse section; kind of simple trichomes (trichome-types 1–4); epidermal cell anticlinal wall undulation and whether visible or not on cuticular surface; resin ducts present/absent in medullary parenchyma of midrib. These characters have been used in a key to the species. Some evidence is given that the lacquer covering the leaf surface of some species is produced by the terminal cells of the glandular trichomes.     

Assessing allometric models to predict vegetative growth of mango (Mangifera indica; Anacardiaceae) at the current-year branch scale

? Premise of the study: Accurate and reliable predictive models are necessary to estimate nondestructively key variables for plant growth studies such as leaf area and leaf, stem, and total biomass. Predictive models are lacking at the current-year branch scale despite the importance of this scale in plant science. ? Methods: We calibrated allometric models to estimate leaf area and stem and branch (leaves + stem) mass of current-year branches, i.e., branches several months old studied at the end of the vegetative growth season, of four mango cultivars on the basis of their basal cross-sectional area. The effects of year, site, and cultivar were tested. Models were validated with independent data and prediction accuracy was evaluated with the appropriate statistics. ? Key results: Models revealed a positive allometry between dependent and independent variables, whose y-intercept but not the slope, was affected by the cultivar. The effects of year and site were negligible. For each branch characteristic, cultivar-specific models were more accurate than common models built with pooled data from the four cultivars. Prediction quality was satisfactory but with data dispersion around the models, particularly for large values. ? Conclusions: Leaf area and stem and branch mass of mango current-year branches could be satisfactorily estimated on the basis of branch basal cross-sectional area with cultivar-specific allometric models. The results suggested that, in addition to the heteroscedastic behavior of the variables studied, model accuracy was probably related to the functional plasticity of branches in relation to the light environment and/or to the number of growth units composing the branches.     

Photosynthetic acclimation of Pinus taeda (loblolly pine) to long-term growth in elevated pCO2 (FACE)

Growth in elevated pCO₂ generally leads to a stimulation of net CO₂ uptake rate. However, with long‐term growth the magnitude of this stimulation is often reduced. This phenomenon, termed acclimation, has been largely attributed to a loss of Rubisco (ribulose 1,5 bisphosphate carboxylase). The mechanism by which Rubisco content declines with long‐term growth is not certain. There is evidence for a sugar‐mediated, selective down‐regulation of Rubisco protein and also for a non‐selective loss of total leaf nitrogen, which impacts Rubisco levels indirectly. Over a season, and including needles at different developmental stages, we investigated these two potential mechanisms in well‐developed Pinus taeda grown for approximately 2·5 years in elevated (56 Pa) pCO₂ using free air CO₂ enrichment technology. Photosynthetic acclimation, as manifested by a decrease in the activity of Rubisco measured both in vivo (? 25%, via gas exchange) and in vitro (? 35%, via enzyme assays), was observed with growth in elevated pCO₂. This acclimation was observed in one‐year‐old needles but not in current‐year needles. Needles exhibiting acclimation had reduced levels of Lsu Rubisco (? 25%) and an increased foliar carbohydrate content (+ 30%) but showed no evidence of a decrease in needle nitrogen or total protein content. These data support the concept that photosynthetic acclimation in elevated pCO₂ is caused by a selective down‐regulation of Rubisco.     

Physiological and growth responses of switchgrass (Panicum virgatum L.) in native stands under passive air temperature manipulation

In the central Great Plains of North America, climate change predictions include increases in mean annual temperature of 1.5–5.5 °C by 2100. Ecosystem responses to increased temperatures are likely to be regulated by dominant plant species, such as the potential biofuel species Panicum virgatum (switchgrass) in the tallgrass prairie. To describe the potential physiological and whole‐plant responses of this species to future changes in air temperatures, we used louvered open‐sided chambers (louvered OSC; 1 × 1 m, adjustable height) to passively alter canopy temperature in native stands of P. virgatum growing in tallgrass prairie at varying topographic positions (upland/lowland). The altered temperature treatment decreased daily mean temperatures by 1 °C and maximum temperatures by 4 °C in May and June, lowered daytime stomatal conductance and transpiration, decreased tiller density, increased specific leaf area, and delayed flowering. Among topographic contrasts, aboveground biomass, flowering tiller density, and tiller weight were greater in lowland sites compared to upland sites, with no temperature treatment interactions. Differences in biomass production responded more to topography than the altered temperature treatment, as soil water status varied considerably between topographic positions. These results indicate that while water availability as a function of topography was a strong driver of plant biomass, many leaf‐level physiological processes were responsive to the small decreases in daily mean and maximum temperature, irrespective of landscape position. The varying responses of leaf‐level gas exchange and whole‐plant growth of P. virgatum in native stands to altered air temperature or topographic position illustrate that accurately forecasting yields for P. virgatum in mixed communities will require greater integration of physiological responses to simulated climate change (increased temperature) and resource availability over natural environmental gradients (soil moisture).     

Soybean leaf growth and gas exchange response to drought under carbon dioxide enrichment

This study was conducted to determine the response in leaf growth and gas exchange of soybean (Glycine max Merr.) to the combined effects of water deficits and carbon dioxide (CO₂) enrichment. Plants grown in pots were allowed to develop initially in a glasshouse under ambient CO₂ and well-watered conditions. Four-week old plants were transferred into two different glasshouses with either ambient (360 μmol mol^-1) or elevated (700 μmol mol^-1) CO₂. Following a 2-day acclimation period, the soil of the drought-stressed pots was allowed to dry slowly over a 2-week period. The stressed pots were watered daily so that the soil dried at an equivalent rate under the two CO₂ levels. Elevated [CO₂] decreased water loss rate and increased leaf area development and photosynthetic rate under both well-watered and drought-stressed conditions. There was, however, no significant effect of [CO₂] in the response relative to soil water content of normalized leaf gas exchange and leaf area. The drought response based on soil water content for transpiration, leaf area, and photosynthesis provide an effective method for describing the responses of soybean physiological processes to the available soil water, independent of [CO₂].     

Phenology and growth of Fagus sylvatica and Quercus robur seedlings in response to temperature variation in the parental versus offspring generation

• Plants are known to respond to warming temperatures. Few studies, however, have included the temperature experienced by the parent plant in the experimental design, in spite of the importance of this factor for population dynamics.
• We investigated the phenological and growth responses of seedlings of two key temperate tree species (Fagus sylvatica and Quercus robur) to spatiotemporal temperature variation during the reproductive period (parental generation) and experimental warming of the offspring. To this end, we sampled oak and beech seedlings of different ages (1–5 years) from isolated mother trees and planted the seedlings in a common garden.
• Warming of the seedlings advanced bud burst in both species. In oak seedlings, higher temperatures experienced by mother trees during the reproductive period delayed bud burst in control conditions, but advanced bud burst in heated seedlings. In beech seedlings, bud burst timing advanced both with increasing temperatures during the reproductive period of the parents and with experimental warming of the seedlings. Relative diameter growth was enhanced in control oak seedlings but decreased with warming when the mother plant experienced higher temperatures during the reproductive period.
• Overall, oak displayed more plastic responses to temperatures than beech. Our results emphasise that temperature during the reproductive period can be a potential determinant of tree responses to climate change.

     

华南三省(区)2001—2020年植被物候时空变化

为深入了解气候变化对我国热带亚热带季风区植被物候的影响,该文基于2001—2020年MODIS EVI时序数据,采用Double Logistic法和阈值法提取华南三省(区)植被物候参数,分析了华南三省(区)植被物候的时空变化特征。结果表明, 研究区植被返青期主要集中在第90~105天,枯黄期在第320~335天,生长季在第220~235天。20年来植被返青期推迟,枯黄期基本不变,生长季缩短。在空间分布上,返青期在两广地区自西向东、自北向南逐渐推迟,海南则自东北向西南逐渐推迟;枯黄期表现为在两广中部晚、周边早,在海南中部早、周边晚的分布特征;生长季在两广地区整体自西向东逐渐缩短,在海南则自西南向东北逐渐延长。随着海拔增高,不同地区和不同植被的返青期差异较大,且波动性较大,而枯黄期先推迟后提前,生长季先延长后缩短。这揭示了气候变暖背景下华南三省(区)植被物候的变化特征,对更全面认识我国南方植被对气候变暖的响应有指导意义。     

The plant growth regulator activity of the fungicide,epoxiconazole, on Galium aparine L. (cleavers)

The plant growth regulator activity of epoxiconazole, a new triazole fungicide, was investigated by time-course, dose-response and histology experiments with Galium aparine L. (cleavers). Seven days after treatment with 125g ai ha^–1 epoxiconazole (field rate), plant height was reduced by 43%. After seventeen days, leaflet area was reduced by 27% but leaflet fresh weight was not significantly influenced. This was partly because leaflet thickness had increased by 20% following epoxiconazole application. Chlorophyll concentrations were also increased on a unit area basis. Examination of leaflet anatomy showed that epoxiconazole elongated palisade, spongy mesophyll and upper epidermal cells. For example, 125g ai ha^–1 caused a 35% increase in the length of spongy mesophyll cells. Epoxiconazole also prevented cell separation as there were significantly more palisade and spongy mesophyll cells per unit area than in leaflets sprayed with water. Stem development was reduced and 125g ai ha^–1 inhibited the elongation of pith cells in stem tissue by 53%. However, the simultaneous application of gibberellin A₃ (GA₃) with epoxiconazole resulted in stem elongation similar to that of control plants. These observations are consistent with the expected effects following the inhibition of cytochrome P-450 dependent enzyme activity.Abbreviations GA₃ gibberellin A₃ - g ai ha^–1 grams of active ingredient per hectare - L ha^–1 litres per hectare - PPFD photosynthetic photon flux density - RH relative humidity - SE standard error     

Morpho-anatomical features of the leaves of the mediterranean geophyteUrginea maritima (L) baker (Liliaceae)

The morpho-anatomy and histochemistry of the hysteranthous leaf ofUrginea maritima (L.) Baker and its adaptive strategies to the Mediterranean climate were investigated. The leaf ofU. maritima is 714 μm thick and possesses moderate specific leaf mass (8.564 mg cm^-2) and low tissue density (136.5 mg cm^-3). The epidermal cells are compactly arranged and covered with cuticle. The average density of stomata in lower epidermis is higher than that of the upper one. The mesophyll cells occupy 52.96% of the total volume of the leaf, while the mesophyll intercellular spaces and the air spaces occupy 30.41%. Idioblastic cells containing raphide bundles and different phenotypes of crystalloid inclusions, embedded in polysaccharides, occur in the lower side of the mesophyll. The presence of oil droplets and lipids is evident. Bundle sheath cells are hardly visible with no chloroplasts which are a pronounced C₃ plant character. Plastids containing protein crystalloid inclusions are abundant in the protophloem sieve elements.U. maritima, a deciduous plant, possesses leaves with mesophytic characters, in order to optimize its adaptation to the seasonal fluctuation of environmental conditions of the Mediterranean climate.     

Preferences, patterns and consequences of branch removal on the dioecious tropical tree Spondias purpurea (Anacardiaceae) by the insect borer Oncideres albomarginata chamela (Cerambycidae)

Most studies of plant–herbivore interactions in dioecious species have evaluated foliar herbivory. In this studie we evaluated preferences of branch removal by the insect borer Oncideres albomarginata chamela in the tropical dioecious tree Spondias purpurea L. The objectives were to determine the preferences and patterns of the removal of branches, to evaluate the effect of branch removal in the vegetative regeneration of branches, and to evaluate the effect of branch removal on the regeneration of fertile branches of male and female trees of S. purpurea . During three consecutive years of study, damage caused to branches by the girdled borer was associated with plant gender. The proportion of branches removed by the insect was greater for female than for male trees. The effects of branch removal were evaluated in attacked regenerated and unattacked branches. Removed branches regenerated a year after the insect borer attacked them. Branch removal affected the probability of producing fertile branches. The preference by O. a. chamela is apparently associated with the nutritional quality of the host.     

Estimation of the anatomical, stomatal and biochemical components of differences in photosynthesis and transpiration of wild-type and transgenic (expressing yeast-derived invertase targeted to the vacuole) tobacco leaves

Photosynthesis and transpiration rates of transgenic (expressing yeast-derived invertase targeted to the vacuole) tobacco (Nicotiana tabacum L.) leaves were, respectively, 50 and 70% of those of a wild type at 20°C, 350 cm³ m^?3 CO₂ concentration, 450 μmol (photons) m^?2 s^?1 of light intensity, and 70% relative air humidity. These differences could be attributed: (a) to changes in leaf anatomy and, consequently, to changes in gases diffusion between the cells' surfaces and the atmosphere; (b) to different stomatal apertures, and, for the photosynthesis rate, (c) to the altered CO₂ assimilation rate. Our objective was to estimate the relative contributions of these three sources of difference. Measurements on the wild-type and the transgenic leaf cross-sections gave values for the cell area index (CAI, cell area surface per unit of leaf area surface) of 15.91 and 13.97, respectively. The two-dimensional model 2DLEAF for leaf gas exchange was used to estimate quantitatively anatomical, stomatal and biochemical components of these differences. Transpiration rate was equal to 0.9 for the wild-type and to 0.63 mmol m^?2 s^?1 for the transgenic leaf: 24.0% of the difference (0.066 mmol m^?2 s^?1 was caused by the greater cell area surface in the wild-type leaf, and 66.0% was caused by a smaller stomatal aperture in the transgenic leaf. Photosynthetic rate was 3.10 and 1.55 μmol m^?2 s^?1 for the wild-type and transgenic leaves, respectively. Only 10.3% of this difference (0.16 μmol m^?2 s^?1) was caused by the difference in CAI, and the remaining 89.7% was caused by altered CO₂ assimilation rate.     

Solar light effects on growth,net photosynthesis,and leaf morphology of in vitro kiwifruit (Actinidia deliciosa) CV hayward

Summary Proliferating axillary shoots of kiwifruit (Actinidia deliciosa A. Chev., C. F. Liang and A. R. Ferguson), var.deliciosa, cv. ‘Hayward’ were grown under solar (SL), white (WL), and blue (BL) light regimens to determine the accumulation of fresh and dry weight, proliferation rate, shoot growth (length), and the net leaf photosynthetic capacity at the CO₂ concentration ranges of 200 to 350, 400 to 600, and 1200 to 1500 ppm. An histologic study determined the effects of light source on leaf stomatal density and tissue morphology. Dry and fresh matter accumulation was greatest, but callus development most limited under the SL regimen. Shoot proliferation was highest under WL and length under BL. Net photosynthetic capacity was highest for leaves grown under SL and lowest for those under BL; the leaves exposed to the latter regimen were also thinner and exhibited a less compact arrangement of palisade cells than those under WL and SL. Leaf stomata density was highest under the BL source.     

Three-year field response of young olive trees (Olea europaea L., cv. Arbequina) to soil salinity: Trunk growth and leaf ion accumulation

Irrigated olive is rapidly increasing in arid and semiarid areas, many of which may be negatively affected by soil salinity. We evaluated changes in trunk growth and leaf Cl^–, Na⁺ and K⁺ concentrations in young Arbequina olives (Olea europaea L.) grown in a saline-sodic field over a three-year period. The trunk diameter was measured at the beginning and the end of the 1999 (70 trees), 2000 (59 trees) and 2001 (42 trees) growing periods. Leaves, sampled in August of each year, were analyzed for Cl^–, Na⁺ and K⁺ concentrations. Soil salinity (apparent electrical conductivity, ECa) of each monitored tree was measured 14 times during the 1999–2001 experimental period with an electromagnetic sensor and converted to root zone electrical conductivity of the soil saturation extract (ECe) based on ECa–ECe calibration curves. Salinity tolerance was determined using the Maas and Hoffman threshold–slope response model. Based on salinity thresholds (ECe_thr), the tolerance of olive in terms of trunk growth was high in 1999 (ECe_thr = 6.7 dS m^–1), but declined with age and time of exposure to salts by 30% in 2000 (ECe_thr = 4.7 dS m^–1) and by 55% in 2001 (ECe_thr = 3.0 dS m^–1). Based on the high absolute slopes obtained in all years (values between 16% and 23% dS^–1 m), olive was classified as very sensitive to ECe values above the threshold. Trunk growth thresholds based on leaf ion concentrations varied, depending on years, between 2.6 and 4.0 mg g^–1 (Cl_thr) and between 1.0 and 1.2 mg g^–1 (Na_thr), indicating that Arbequina olive was less sensitive to leaf Cl^– and much more sensitive to leaf Na⁺ than values reported as toxic in greenhouse studies. Leaf K⁺ slightly decreased with increasing salinity, whereas the K⁺/Na⁺ ratio sharply decreased with increasing salinity. We concluded that the initial salinity tolerance of olive was high, but declined sharply with time of exposure to salts and became quite sensitive due primarily to increasing toxic concentrations of Na⁺ in the leaves.     

Phylogenetic analysis based on structural and combined analyses of Rhus s.s. (Anacardiaceae)

Structural data were combined with trnL‐F and internal transcribed spacer sequences from other studies and with new sequences representing ten additional species to clarify the phylogenetic relationships of Rhus s.s. These data indicate that Rhus s.s and both subgenera, Rhus and Lobadium, are monophyletic. The genus Rhus is supported as monophyletic by the presence of red glandular hairs on the berries and inflorescence axis, cilia on the sepals and glands on the leaf blades. Subgenus Rhus can be identified by the presence of more than seven resin channels in the petiole, weakly percurrent tertiary veins and a type I vascular system in the mid‐vein. Subgenus Lobadium is characterized by the presence of short bracteoles and pedicels. This subgenus is divided into four sections, Lobadium, Rhoeidium, Styphonia and Terebinthifolia. Section Lobadium has trifoliate leaves; section Rhoeidium is monotypic, including only Rhus microphylla; section Styphonia is supported by five synapomorphies, including an incomplete marginal vein, fibres in the petiole, a thick cuticle, two layers of palisade parenchyma and prismatic crystals in the mesophyll; and section Terebinthifolia has gelatinous xylary fibres in the petiole. Hypotheses about the evolutionary changes of these characters are presented based on the cladograms. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 452–468.     

Comparative effects of light during growth on the photosynthetic properties of NADP-ME type C4 grasses from open and shaded habitats. I. Gas exchange,leaf anatomy and ultrastructure*

Abstract Maximum photosynthetic rate (P_max in Zea mays L. was reduced to a much greater extent by neutral shading during growth than in the shade-adapted C₄ grass Paspalum conjugatum Berg., although under a high light regime the P_max of Z. mays was two-fold higher than that of P. conjugatum. In both species the shade-induced reductions of P_max were not of stomatal origin since the intercellular CO₂ concentration (C_i) was not decreased by growth under low light levels. The C_i of P. conjugatum (～200 μPa Pa^?1) measured at air levels of CO₂ and high photon flux densities was 30% greater than that of Z. mays and, concomitantly, leaf water use efficiency was less. As with P_max, specific leaf weight, leaf thickness and chlorenchyma volume were reduced to a greater extent by shading in Z. mays than in P. conjugatum. In contrast to Z. mays, bundle sheath chloroplasts of P. conjugatum contained well-defined stacks of grana. Mesophyll chloroplasts of P. conjugatum developed under a high light regime also contained large amounts of starch. This was not the case with Z. mays.     

Phenology of Tick weed (Cleome viscosa L.) and its interaction with okra (Abelmoschus esculentus (L.) Moench) and Melodoigyne incognita

Cleome viscosa is an emerging weed with the potential of interfering with okra and influencing pests of okra. Screen house studies were conducted on the phenology of C. viscosa, its interference with okra and its interaction with root-knot nematode-infected okra. Seedlings of C. viscosa were monitored in pots for growth, yield and dry matter accumulation for 14 weeks. C. viscosa was planted with okra at densities 0, 2, 4, 6, 8 and 10 weeds per okra plant and observed for 11 weeks. Data were collected on growth, yield and dry matter of okra. Plants were inoculated with 2,500 M. incognita eggs per pot while control plants were not inoculated. C. viscosa attained 91.7 cm height and accumulated 7.8 g/plant biomass at 14 weeks after planting. The percentage reduction in okra plant height, plant dry weight and fruit yield due to interference at lowest cleome density (2 plants/pot) was 33.7, 83.6 and 82.1%, respectively. Nematode reproductive factor was significantly lower for okra alone (4.9) compared to okra with cleome (7.6). This study shows that C. viscosa is a fast-growing weed that suppressed the performance of okra even at low density, is a good host to M. incognita and increased the population of the nematode in soil.     

Growth Rings,Phenology, Hurricane Disturbance and Climate in Cyrilla racemiflora L., a Rain Forest Tree of the Luquillo Mountains,Puerto Rico1

The growth phenology of Cyrilla racemiflora L., the dominant tree species of the montane rain forest, (subtropical lower montane rain forest, sensu Holdridge) of the Luquillo Mountains of Puerto Rico was studied intensively during 1989, and then semiannually through mid-1993 to determine the periodicity of changes in xylem structure. Four trees at 770 m were monitored for flowering, branch elongation, leaf litterfall, and xylem cell growth and differentiation in the lower stem, and these events were related to local seasonal patterns of rainfall and temperature. Hurricane Hugo defoliated study trees in September, 1989. Bud-break and branch elongation in March, 1989 were followed by earlywood xylem cell production in the lower stem in April and the onset of flowering in May. Leaf litterfall was greatest between April and June, coinciding with peak branch growth and new leaf formation. Latewood xylem was produced in December. The general phenological pattern was synchronized between trees and over study years. Vessel diameter and density were monitored along with thickness of earlywood and latewood and the former converted to vessel lumen area, a measure of xylem conductance capacity. Annual growth rings were formed with periods of earlywood and latewood production coinciding with traditional summer (rainy) and winter (dry) seasons, respectively, in the Luquillo Mountains. Hurricane defoliation was followed by heavy flowering in 1990, a year of reduced branch elongation and annual xylem ring width, and was associated with maximum vessel lumen area, as was flowering in 1989, prior to the hurricane. Hurricane Hugo provided a perturbation that, through its elicited stress response, allowed for the demonstration of the interplay between flowering, branching, structural growth of xylem, and xylem function.