Nymphaea Mexicana Research Articles

Distribution and host preference of a potential biocontrol agent with a new association for the alien water lily Nymphaea mexicana in South Africa

Although classical biological control makes use of natural enemies from the native range of an invasive alien species, there are occurrences in which species in the invaded range expand their host range and form new associations with the invader. Bagous longulus Gyllenhal (Coleoptera: Curculionidae) is a South African native weevil hosted by the native water lilies Nymphaea nouchali Burm. f. and Nymphaea lotus L. (family Nymphaeaceae), and it has formed a new association with the invasive alien water lily Nymphaea mexicana Zuccarini. Host range expansions of more-specialist native herbivores on alien invasive plant species occur relatively infrequently; therefore, we investigated the potential of this weevil as another means of managing N. mexicana in South Africa through augmentative biological control. Field surveys were conducted in 2021 and 2022 to determine the distribution of the weevil, and host-specificity tests were conducted under greenhouse conditions to understand its preference for its natural host as compared with N. mexicana and an exotic Nymphaea hybrid. The weevil was widely distributed at 31 surveyed sites across the country but was found feeding and completing lifecycles on only Nymphaea species, including the native hosts and the alien invasive N. mexicana. Additionally, there were no major differences in feeding preference for its natural host when compared with N. mexicana, but the Nymphaea hybrid tested was less preferred. The narrow host range of this weevil, its presence and impact on N. mexicana at three invaded sites, and the fact that a classical biological control agent has not yet been approved, all suggest a potential for B. longulus to be released augmentatively to manage N. mexicana in South Africa. Even so, possible risks such as increased herbivory on native Nymphaea species with augmented populations of its natural enemy should be carefully considered and tested before implementation.

Aquatic plant Nymphaea mexicana as a viable feedstock for second-generation biofuel production

Aquatic plant Nymphaea mexicana as a viable feedstock for second-generation biofuel production

Know thy enemy: Investigating genetic contributions from putative parents of invasive Nymphaea mexicana hybrids in South Africa as part of efforts to develop biological control

Hybridisation of alien invasive plants complicates efforts to develop biological control, because variations in the genetic makeup of the target plant can impact the survival of host specific agents that have evolved adaptations specific to the original host. To maximise the likelihood of success in a biological control program, potential agents should therefore be collected from populations in the region of origin that are genetically similar to plants in the invaded range. Molecular markers are useful tools to understand genetic contributions in hybrid populations, especially where morphological differentiation is difficult. Nymphaea mexicana Zuccarini (Nymphaeaceae) is an invasive alien plant in South Africa that is being targeted for biological control, but hybrids with intermediate morphological traits are also present at several sites. In this study, ISSR (inter simple sequence repeats) and ITS (internal transcribed spacer) markers were used to determine which Nymphaea species are likely to be putative parents of these hybrids, and morphological characters were also investigated to determine if genetic and morphological traits matched. Two major hybrid groups were identified, with one group clustering with Nymphaea odorata Aiton and the other clustering with Nymphaea alba L. A third, smaller group clustered with Nymphaea tetragona Georgi, whereas the remaining samples clustered with pure N. mexicana from the native range. Morphological features agreed with deductions drawn from molecular data. These results allow us to focus efforts to find compatible biological control agents and better understand the complicated genetic structure of N. mexicana and Nymphaea hybrids in South Africa.

Love at first bite? Pre-release surveys reveal a novel association between a native weevil and the invasive Nymphaea mexicana Zuccarini (Nymphaeaceae) in South Africa

Classical biological control aims to suppress alien invasive plant populations by introducing host-specific natural enemies from the native range. This relies on the assumption that invasive plant populations in the invaded range benefit from the release of natural enemies. Pre-release surveys in the invaded range are a useful way to determine if enemy release applies to a particular invasive alien plant, and to determine what other factors may contribute to the invasion. Similarly, pre-release surveys gather information that can be used to compare invaded sites before and after the release of biological control agents and may also identify whether natural enemies have been accidentally introduced into the country. Pre-release surveys were conducted in South Africa on the invasive Nymphaea mexicana Zuccarini (Nymphaeaceae) to gather such information about this species, for which a biological control programme is being developed. There was lower diversity and abundance of herbivores in the native range compared to South Africa, suggesting that N. mexicana does experience enemy release at most sites in South Africa. This support for the enemy release hypothesis justifies the investment in biological control for its management. However, a native weevil, Bagous longulus Gyllenhal (Coleoptera: Curculionidae), was found feeding and reproducing on N. mexicana at three sites, resulting in damage to the leaves and suggesting that a novel association has formed between these species. Bagous longulus may have potential to be distributed to sites of N. mexicana where it is not present, though further investigation is necessary to confirm if its host range is suitable for this to be a safe endeavour. With the exception of sites where B. longulus was present, leaf sizes were large and damage was low, and there is no evidence that any natural enemies have been accidentally introduced from the native range. Findings such as these emphasise the importance of conducting thorough surveys during the development of biological control programmes.

Isolation and Characterization of Flavonoid Naringenin and Evaluation of Cytotoxic and Biological Efficacy of Water Lilly (Nymphaea mexicana Zucc.).

Despite its limited exploration, Nymphaea mexicana Zucc. can be beneficial if pharmacology, isolation, and biological evaluation are given attention. It is an aquatic species that belongs to the family Nymphaeaceae. The thrust area of the work was the extraction, isolation, and biological evaluation of different extracts of the N. mexicana Zucc. plant. The primary goal of this research was to assess the antimicrobial, antioxidant, and anticancer activities of the extracts and to isolate the target naringenin compound. Comparative FT IR analysis of different extracts of this plant revealed the presence of functional groups of plant secondary metabolites, including polyphenols, flavonoids, terpenoids, esters, amines, glycosides, alkanes, alkaloids, fatty acids, and alcohols. Moderate free radical scavenging potential has been achieved for the various extracts via reducing power and DPPH assays. While cytotoxic activity was evaluated by colorimetric and lactate dehydrogenase cell viability tests on potent cancer cell lines. Lung adenocarcinoma epithelial cells (A-549), and breast cells (MC-7) were treated with MeOH extract. The antimicrobial activity against bacterial strains was evaluated using Gram-positive and -negative cultures, where maximum and minimum inhibition zones were recorded for different strains, including 1.6-25.6 μg/mL for Streptococcus aureus, using the agar well diffusion method. In addition, the anti-inflammatory activity of different extracts of N. mexicana Zucc. was evaluated in a nitrite radical scavenging assay with high concentrations of secondary metabolites, which are important against human pathogens and other diseases.

A Review of the Biocontrol Programmes Against Aquatic Weeds in South Africa

Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis & Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.

Population genetics of invasive and native Nymphaea mexicana Zuccarini: Taking the first steps to initiate a biological control programme in South Africa

Nymphaea mexicana Zuccarini (Nympheaceae) (Mexican waterlily) is a rooted floating-leaved aquatic plant native to southern USA and Mexico that has become a problematic invasive alien plant in South Africa. Biological control is considered a desirable management strategy for the plant in South Africa. A good understanding of the genetic structure of invasive populations has been useful in other biological control programmes because taxonomic uncertainty about the target plant can result in natural enemies that are not adapted to the invasive populations being considered as potential agents. For N. mexicana, hybrids exist in the wild and horticultural trade, but identification is difficult, so understanding the genetic structure of populations is required to ensure that potential agents are collected off plants similar to invasive populations in South Africa. ISSR (inter-simple sequence repeats) analysis was used to determine whether invasive N. mexicana populations from South Africa were genetically similar to native range populations from USA or whether they were hybrids. Results from these analyses were matched with the morphotypes of each population based on petal colour, shape, and size. The genotypes suggested by the ISSR analyses corroborated the presence of both hybrid and pure forms of N. mexicana in South Africa. Populations of N. mexicana in the invaded range that are genetically similar to native range populations are more likely to be suitable for biological control, while other populations are likely to be hybrids formed by crossing of parents from the native range or within the horticultural trade, which may present difficulties for management using biocontrol.

Insect Herbivores Associated with Nymphaea mexicana (Nymphaeaceae) in Southern United States: Potential Biological Control Agents for South Africa

Nymphaea mexicana Zuccarini (Nymphaeaceae) (Mexican waterlily) is an emergent floating-leaved aquatic plant from the southeastern USA that is invasive in South Africa. In invaded waterbodies this plant restricts water movement, increases siltation, decreases recreational activities, and can deplete water oxygen levels, which in turn negatively impacts aquatic fauna. Currently there are no chemical, mechanical, or biological control programs in place for N. mexicana in South Africa, but the sustainability of biological control makes this the most desirable option. Field surveys for potential biological control agents were conducted in the native range of N. mexicana in Florida, Louisiana, and Texas from Aug to Oct 2018. Leaves, stems, flowers, and roots of N. mexicana were searched for insect herbivores by hand and using Berlese funnels. Insects were prioritized for use as biological control agents by considering the extent and type of feeding damage, field host range, and incidence (percentage of sites in which each species was found). In total, 15 confirmed species were found feeding on N. mexicana, and some taxa were identified only to family level. Incidence coverage estimator mean, MMRuns, Chao 2 mean, and Chao 2 upper 95% CI species accumulation estimators predicted that between 2 and 5 species were missed during the surveys. Based on field observations, Bagous americanus LeConte (Coleoptera: Curculionidae), and Megamelus toddi Beamer (Hemiptera: Delphacidae) were prioritized. Host specificity trials will be conducted to determine whether these insects may be used as biological control agents of N. mexicana.

Comparative Phytochemical investigation and Antioxidant study of Narcicuss tazetta, Nymphaea mexicana zucc. And Indigofera heterantha.

The study was intended to investigate the presence of phytoconstituents in the bulbs of Narcicuss tazetta, flowers of the plant Nymphaea mexicana, and roots of Indigofera heterantha. The present study provides evidence that methanolic extracts of Narcicuss tazetta, Nymphaea mexicana and Indigofera heterantha contain important compounds with marked bioactivity. Maximum phenolic content was observed in Nymphaea mexicana and maximum flavonoid content was observed in extract of Indigofera heterantha.
 Keywords: Phytoconstituents, Antioxidant, Nymphaea mexicana, Narcicuss tazetta, Indigofera heterantha

挺水植物与浮叶植物光合荧光特性的差异

PDF HTML阅读 XML下载 导出引用 引用提醒 挺水植物与浮叶植物光合荧光特性的差异 DOI: 10.5846/stxb201704120652 作者: 作者单位: 南京大学生命科学学院,南京大学生命科学学院,南京大学生命科学学院,南京大学生命科学学院,南京大学生命科学学院,南京大学生命科学学院,南京大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 江苏省重点研发计划（现代农业项目）（BE2015357）；江苏省林业三新工程项目（LYSX[2015]16）；国家海洋局海洋公益性行业科研专项经费项目（201505023）；国家基础科学人才培养基金项目（J1210026）；中央高校基本科研业务经费项目（020814380026，020814380034） Photosynthetic characteristics differ between emergent and floating-leaved macrophytes Author: Affiliation: Nanjing University,Nanjing University,Nanjing University,Nanjing University,Nanjing University,Nanjing University,Nanjing University Fund Project: Fundamental Research Plan of Jiangsu Province (Modern Agriculture program, BE 2015357), Forestry “San-Xin” project of Jiangsu Province ( LYSX [2015] 16), The State Oceanic Administration of public welfare scientific research funding (201505023), National Undergraduate Innovation Program of China (J1210026), Fundamental Research Funds for the Central Universities (020814380026, 020814380034) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探讨自然生境中不同生活型水生植物光合生理特征的差异，选取4种挺水植物菖蒲（Acorus calamus L.）、再力花（Thalia dealbata Fraser）、梭鱼草（Pontederia cordata L.）、茭草（Zizania latifolia（Griseb.）Stapf），以及4种浮叶植物黄睡莲（Nymphaea mexicana Zucc.）、莼菜（Brasenia schreberi J.F.Gmel.）、金银莲花（Nymphoides indica（L.）O.Kuntze）、菱（Trapa bispinosa Roxb.）为研究对象，比较其叶绿素荧光参数、色素组成和比叶重的差异。研究发现，高光强下挺水植物电子传递速率（ETR）、非光化学淬灭（NPQ）等光合荧光参数、以及低光强下ETR拟合曲线的初始斜率（α）均值显著大于浮叶植物。不同挺水植物间光系统Ⅱ（PSⅡ）最大光化学效率（Fv/Fm）、ETR、NPQ、最大潜在电子传递速率（Ps）、最大电子传递速率（ETRm）及饱和光强（Em）变化幅度较大；不同浮叶植物间上述参数变化幅度较小。挺水植物叶绿素（Chls）、类胡萝卜素（Cars）含量均值也高于浮叶植物。但由于比叶重（SLW）的影响，不同水生植物间单位叶面积和单位叶鲜重色素含量的变化规律略有不同。挺水植物中再力花、梭鱼草光合能力较强，其光合荧光参数和色素比例均符合典型阳生型特征；菖蒲、茭草光合能力略弱，部分指标符合阴生型特征。4种浮叶植物各指标均符合阳生型特征。实验推测，挺水植物和浮叶植物由于叶片所处环境不同，其光合适应机制存在明显分化。挺水植物叶片所处环境异质性较大，因而不同物种之间光合参数适应范围也大；浮叶植物叶片所处环境相对均一，因而光合参数差异也小。浮叶植物也不依赖NPQ进行高光保护。在湿地植被恢复工具种筛选过程中应综合考虑环境异质性和不同物种光适应能力的差异。 Abstract:Emergent and floating-leaved macrophytes, two different life forms of primary producers in shallow lakes and riparian zones, play important roles in nutrient cycling and energy flow of aquatic ecosystems. To investigate the differences in photosynthetic characteristics between the two forms of macrophytes, chlorophyll fluorescence, pigment composition, and special leaf weight (SLW) of four emergent macrophytes (Acorus calamus L., Pontederia cordata L., Thalia dealbata Fraser, Zizania latifolia (Griseb.) Stapf) and four floating-leaved macrophytes (Nymphaea mexicana Zucc., Brasenia schreberi J. F. Gmel., Nymphoides indica (L.) O. Kuntze, Trapa bispinosa Roxb.) growing in natural habitats were compared. In general, emergent macrophytes showed higher electron transport rate (ETR) and non-photochemical quenching (NPQ) under high irradiation, as well as relatively higher initial slope (α) of ETR curve under low light, than did floating-leaved plants. Broader ranges on maximum quantum yield of PSⅡ (Fv/Fm), ETR, NPQ, maximum potential ETR (Ps), maximum ETR (ETRm) and saturating irradiance (Em) were also found among different species of emergent macrophytes. Average chlorophyll (Chls) and carotenoid (Cars) contents were also higher in emergent macrophytes than in floating-leaved ones. However, due to the discrepancy of SLW, the trends of pigment amount among species on a fresh matter basis differed from those per leaf area unit. Among the four emergent macrophytes, T. dealbata and P. cordata exhibited relatively higher photosynthetic ability, and all fluorescence parameters together with pigment ratios (Chl a/b, Chls/Cars) indicated they belonged to the sun type. However, A. calamus and Z. latifolia exhibited relatively lower photosynthetic ability, and part of the parameters were closer to the shade type. All four floating-leaved species exhibited as sun type. This suggests that the heterogeneity of environments contributes to the discrepancy of leaf photosynthetic abilities. Emergent leaves grow in highly diverse environments, so their photosynthetic parameters have broad ranges, whereas the environments for floating leaves are relatively stable, so their parameters are limited to small ranges. It may not be necessary for floating-leaved macrophytes to develop NPQ and internal heat dissipation to prevent high irradiation damage. In conclusion, special attention should be paid to both environmental heterogeneity and discrepancy of adaptation abilities when selecting aquatic macrophytes for wetland restoration. 参考文献 相似文献 引证文献

Plastid genome structure and phylogenomics of Nymphaeales: conserved gene order and new insights into relationships

The plastid genomes of early-diverging angiosperms were among the first land plant plastomes investigated. Despite their importance to understanding angiosperm evolution, no investigation has so far compared gene content or gene synteny of these plastid genomes with a focus on the Nymphaeales. Here, we report an evaluation and comparison of gene content, gene synteny and inverted repeat length for a set of 15 plastid genomes of early-diverging angiosperms. Seven plastid genomes of the Nymphaeales were newly sequenced for this investigation. We compare gene order and inverted repeat (IR) length across all genomes, review the gene annotations of previously published genomes, generate a multi-gene alignment of 77 plastid-encoded genes and reconstruct the phylogenetic relationships of the taxa under study. Our results show that gene content and synteny are highly conserved across early-diverging angiosperms: All species analyzed display complete gene synteny when accounting for expansions and contractions of the IRs. This conservation was initially obscured by ambiguous and potentially incorrect gene annotations in previously published genomes. We also report the presence of intact open reading frames across all taxa analyzed. The multi-gene phylogeny displays maximum support for the families Cabombaceae and Hydatellaceae, but no support for a clade of all Nymphaeaceae. It further indicates that the genus Victoria is embedded within Nymphaea. Plastid genomes of Trithuria were found to deviate by numerous substitutions and length changes in the IRs. Phylogenetic analyses further indicate that a previously published plastome named Nymphaea mexicana falls into a clade of N. odorata and should be re-evaluated.

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Speciation in North American water lilies: evidence for the hybrid origin of the newly discovered Canadian endemic Nymphaea loriana sp. nov. (Nymphaeaceae) in a past contact zone

Field observations of morphologically intermediate water lilies in central Canada suggested a hybrid origin involving the parents Nymphaea odorata Aiton and Nymphaea leibergii Morong despite the fertile nature of these plants. Sequencing of the nrITS and the plastid rps4–trnT–trnF regions further including all members of the north temperate Nymphaea subg. Nymphaea clade, and samples from other hybrids occurring in North America in the wild, allowed us to determine that individuals of N. leibergii and of N. odorata were the maternal and paternal parents, respectively. Hybrids of New England have all proven to be sterile, are genetically variable, and probably are F1. By comparison, the plants of east-central Saskatchewan and west-central Manitoba are fully fertile and genetically uniform based on ISSR and sequence data. On the basis of this evidence, the latter are here described as a new species, Nymphaea loriana sp. nov., which may have originated during the Holocene climatic optimum about 6000 years ago in a past contact zone of the parents. Further hybrids detected between N. odorata and Nymphaea tetragona Georgi, as well as between N. leibergii and N. tetragona, were always sterile. Gene trees of the temperate clade of Nymphaea converge on a clade of small-flowered water lilies (sect. Chamaenymphaea), including N. leibergii, N. tetragona, and Nymphaea pygmaea. Nuclear ITS further resolves an American clade (Nymphaea mexicana Zucc. – N. odorata) sister to all remaining species. This split into two major subclades also appears in the otherwise less resolved rps4–trnT–trnF tree. Thus the origin of N. loriana is a reticulation between long-separated parental lineages.

Anti-inflammatory effects of phenolic compounds isolated from the flowers of Nymphaea mexicana Zucc.

Nymphaea mexicana Zucc. is an aquatic plant species which belongs to the family Nymphaea and is commonly known as the yellow water lily. The aim of this work was to study the in vitro antiinflammatory effects of phenolic compounds isolated from the flowers of Nymphaea mexicana Zucc. Seven phenolic compounds including vanillic acid, 4-methoxy-3,5-dihydroxybenzoic acid, (2R,3R)-3,7-dihydroxyflavanone, naringenin (4), kaempferol 3-O-(3-O-acetyl-a-L-rhamnopyranoside), kaempferol 3-O-(2-O-acetyl-a-L-rhamnopyranoside), and quercetin 3-(30 0-acetylrhamnoside) (7) were isolated from the flowers of Nymphaea mexicana Zucc. These results revealed that compound 4 has the most prominent inhibitory effect on the LPS-stimulated nitric oxide (NO), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor-alpha (TNF-a) production in RAW 264.7 macrophages. In addition, compound 4 also inhibited LPS-mediated induction of protein expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and phospho-ERK in RAW 264.7 macrophages. Thus, compound 4 from the flowers of Nymphaea mexicana Zucc. may provide a potential therapeutic approach for inflammation-associated disorders.

Using in situ hyperspectral reflectance data to distinguish nine aquatic plant species

In situ hyperspectral reflectance data were studied at 50 bands (10 nm bandwidth) over the 400–900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus [Nelumbo lutea (Willd.) Pers.], American pondweed (Potamogeton nodusus Poir.), giant duckweed [Spirodela polyrrhiza (L.) Schleid.], Mexican waterlily (Nymphaea mexicana Zucc.), white waterlily (Nymphaea odorata Aiton), spatterdock [Nuphar lutea (L.) Sm.], giant salvinia (Salvinia molesta Mitchell), waterhyacinth [Eichhornia crassipes (Mart.) Solms] and waterlettuce (Pistia stratiotes L.). The species were studied on three dates: 30 May, 1 July and 3 August 2009. All nine species were studied in July and August, while only eight species were studied in May; giant duckweed was not studied in May due to insufficient availability. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that most separations among species occurred at bands 795–865 nm in the near-infrared (NIR) spectral region where up to six species could be distinguished. For July, few species could be distinguished amongthe 50 bands; most separations occurred at the 715 nm red-NIR edge band where four species could be differentiated. The optimum bands in August occurred in the green (525–595 nm), red (605–635 nm) and red-NIR edge (695–705 nm) spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge and NIR spectral regions to be significant to discriminate among the eight species in May. For July and August, stepwise discriminant analysis identified 15bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the nine species.

Pattern of Variation and Systematics of <I>Nymphaea odorata</I>: II. Sequence Information from ITS and <I>trnL-trnF</I>

Sequence data from the nuclear internal transcribed spacer (ITS) and the plastid trnL-trnF regions were used to assess relationships among populations of N. odorata across its North American range, and to evaluate whether subsp. odorata and subsp. tuberosa form distinct taxonomic units. Nymphaea mexicana was included because of suspected hybridization with N. odorata. The trnL-trnF region provided a single informative site in N. odorata. In contrast, the ITS region was more variable. Phylogenetic analysis of ITS data supports the monophyly of the two species. Within N. odorata, two clades were resolved largely representing subsp. odorata and subsp. tuberosa, although a few individuals appeared outside the respective clades. Polymorphic sites were detected in ITS, indicating possible hybridization between the subspecies. The geographic location of these hybrids suggests a possible hybrid zone. Overall, molecular evidence supports the segregation of subsp. odorata and subsp. tuberosa, with limited gene flow between them.

Pattern of Variation and Systematics of <I>Nymphaea odorata</I>: I. Evidence from Morphology and Inter-Simple Sequence Repeats (ISSRs)

Nymphaea odorata, Nymphaeaceae, is the most widely distributed water-lily in North America. Disagreement exists on whether this morphologically variable species should be split into two species, N. odorata and N. tuberosa, or treated as one species with two subspecies. Morphological characters and markers from the inter-simple sequence repeats (ISSRs) were examined to assess taxonomic status and elucidate patterns of genetic variation among populations. This study provides evidence against treatment of N. tuberosa at species rank. The principal component analysis of 26 vegetative characters underscores immense variability, but does partially segregate populations of subsp. odorata and subsp. tuberosa. Based on analysis of variance, a new set of morphological characters is proposed to distinguish the two subspecies: mean leaf blade length-to-width ratio, petiole striping, and lobe apex shape. Results from ISSRs show high polymorphism within and among populations. Genetic variation was found largely within geographical regions (89%) rather than among regions. Principal coordinate (PCOA) analyses and minimum spanning tree (MST) analyses based on ISSRs clearly distinguished Nymphaea mexicana and N. odorata. Within N. odorata, samples of subsp. odorata appear to be a distinct entity, whereas samples largely but not completely separated from samples of subsp. tuberosa. PCOA and MST showed linkage between most samples of subsp. odorata whereas this was less evident in UPGMA.

Nymphaea mexicana Zuccarini in the Iberian Peninsula

Nymphaea mexicana Zuccarini, a species from southern USA and Mexico, is reported for the first time from the Iberian Peninsula. A brief description of the site and taxonomical characteristics are given.

Alkanes of surface waxes from eight species of aquatic angiosperms

Surface waxes from eight species of aquatic angiosperms were extracted. Four species have submerged leaves ( Cabomba caroliniana Gray, Egeria densa Planch., Eriocaulon aquatile Koern. and Mayaca fluviatilis Aubl.), three have emergent leaves ( Eichhornia crassipes (Mart.) Solms, Myriophyllum aquaticum (Vell.) Verdc. and Pistia stratiotes L.) and one has floating leaves ( Nymphaea mexicana Zucc.). In all cases the yield of waxes was low and ranged among the species from 1.1 to 16.1 μg cm −2. The alkanes were separated from the waxes through column chromatography and identified by means of gas chromatography. The carbon chains of the alkanes of the species with submerged leaves are, on average, shorter than those of the species with air-exposed leaves. The distribution of alkanes of the latter species is similar to the alkane profiles of foliar waxes of terrestrial plants.

Floral biology of Nymphaea mexicana zucc. (Nymphaeaceae)

The floral biology of Nymphaea mexicana Zuccarini has been investigated. Anthesis is diurnal with flowers opening and closing for two consecutive days. Flowers on the first day of anthesis are functionally female with the stigmatic papillae secreting a small quantity of fluid. Total dissolved solids of the stigmatic fluid range from 3 to 4%; glucose and fructose are in equal concentrations and a large number of free amino acids are present. Flowers are primarily visited by Dialictus bees, flies and beetles. These insects typically land on the wet stigmatic surface where the secretion loosens pollen from the insects' body. On the second day of anthesis, the anthers dehisce and the stigmatic fluid disappears. This latter phenomenon is associated with a loss of stigmatic receptivity. Since protogyny is complete, flowers are obligatorily entomophilous. After anthesis, the flower closes and submerges. The perianth and androecium abscise and decompose as the fruit matures. The fruit yields large trichomic seeds. The phylogenetic position of N. mexicana within the genus is discussed.