On the natural occurrence of gossypetin 7- and 8-monomethyl ethers

The 7-methyl ether of gossypetin occurs, as a mixture of 4 glycosides, in the yellow inflorescence of Eriogonum nudum. In contrast to previous reports, however, it does not occur in Lotus corniculatus flowers, nor is it present in leaves of Medicago sativa. The 8-methyl ether, which is present in Lotus flowers, has been found for the first time in the Compositae, in flowers of Geraea canescens.     

Luteolin and daphnetin derivatives in the juncaceae and their systematic significance

During a chemosystematic survey of 38 representative species of the Juncaceae for leaf and stem flavonoids, the 5-methyl ether of luteolin was discovered for the first time in plants. It occurs both free and as the 7-glucoside; its identity was confirmed by synthesis. Flavone sulphates were also found in the family and the 7-glucosidesulphates of luteolin and chrysoeriol were characterised for the first time. 7,3′,4′-Trihydroxyflavone and its 7-glucoside, not previously reported in the monocotyledons, were found in three species. The presence of luteolin 5-methyl ether or its glucoside in 70% of the species surveyed serves to distinguish the Juncaceae from the morphologically related Centrolepidaceae, Restionaceae and Thurniaceae. Flavone C-glycosides, common in grasses and sedges, were found only in Prionium, a genus which on anatomical grounds is anomalous in the Juncaceae. Among other phenolics detected during the survey, the uncommon 7,8-dihydroxycoumarin, daphnetin, was identified in Juncus effusus and its 8-methyl ether in four Luzula species. Taken together, these chemical findings show that the Juncaceae are very distinctive in their phenolic pattern and confirm the correctness of assigning them an isolated position in a separate order, the Juncales. The results indicate that the Juncaceae are chemically specialized, in spite of the facts that the family has been regarded as ancestral to the Cyperaceae and Gramineae and that they have been assigned a low advancement index by Sporne.     

Two gossypetin methyl ethers as ultraviolet patterning guides in the flowers of Coronilla valentina

The 3′-monomethyl and 8,3′-dimethyl ethers of gossypetin have been identified in the flowers of Coronilla valentine where they occur as the 3-rutinosides. These two yellow flavonols occur specifically in the wings and thus provide both visible yellow colour and UV absorption to bees, which land on the wings and trigger the self-fertilization mechanism. These yellow pigments are absent from the flowers of the related C. emerus, where their role in UV patterning is taken over by colourless kaempferol and quercetin glycosides.     

Leaf flavonoid patterns in the winteraceae

In a leaf flavonoid survey of 59 specimens of the Winteraceae and related families, representing nine genera, luteolin 7,3′-dimethyl ether (in 77%) and flavonols (in 81%) were found to be major constituents. Indeed the high incidence of luteolin 7,3′-dimethyl ether chemically isolates the family from all other angiosperm groups, including families and genera that have been taxonomically associated with the Winteraceae in the past. Simple flavones (in 16%), on the other hand, were found only in some Drimys s. str., Tasmannia and Pseudowintera species. Similarly, the distribution of flavone C-glycosides was restricted to specimens of T. piperita and one specimen of D. winteri. The frequent occurrence of procyanidin (in 60%) and dihydroquercetin (in 44%) reflects the primitive and woody nature of the family. The combined flavonoid data clearly support previous cytological, morphological and phylogenetic studies in the division of the Winteraceae into three groups of genera: (1) Bubbia, Belliolum, Exospermum and Zygogynum; (2) Drimys s. str. and Pseudowintera and (3) Tasmannia. Some generic variations were found within the Bubbia, Belliolum, Expospermum and Zygogynum group but apart from minor geographic variations within Belliolum the flavonoid results do not appear to provide suitable evidence for subgeneric taxonomy.     

The leaf flavonoids of the orchidaceae

In a leaf survey of 142 species from 75 genera of the Orchidaceae, flavone C-glycosides (in 53%) and flavonols (in 37 %) were found to be the most common constituents. However, since these compounds are not found uniformly and their distribution shows a strong correlation with plant geography, it is not possible to represent the Orchidaceae by a single flavonoid profile. Thus, flavone C-glycosides are most common in tropical and subtropical species of the Epidendroid and Vandoid tribes (in 63%) and flavonol glycosides are more characteristic of temperate species of the Neottioid tribes (in 78%). By contrast 6-hydroxyflavones (in 6 species), luteolin (in 2 species) and tricin as the 5-glucoside (in 1 species) are all rare. Three new glycosides were characterised: scutellarein 6-methyl ether 7-rutinoside from Oncidium excavatum and O. sphacelatum, pectolinarigenin 7-glucoside from 0. excavatutn and Eria javanica, and luteolin 3′,4′-diglucoside from Listera ovata. The xanthones, mangiferin and isomangiferin were found in Mormolyca ringens, Maxillaria aff. luteo-alba and 5 Polystachya species and a mangiferin sulphate tentatively identified in P. nyanzensis. Other unusual phenolic constituents include 6,7-methylenedioxy- and 6,7-dimethoxycoumarins from Dendrobium densiflorum and D. farmeri, formed by the rearrangement during the extraction process from the corresponding O-glucosyloxycinnamic acids. The origin and relationship of the Orchidaceae to other monocot groups are discussed in the light of the flavonoid evidence.     

Allometric analysis of the induced flavonols on the leaf surface of wild tobacco (Nicotiana attenuata)

Trichomes excrete secondary metabolites that may alter the chemical composition of the leaf surface, reducing damage caused by herbivores, pathogens and abiotic stresses. We examined the surface exudates produced by Nicotiana attenuata Torr. Ex Wats., a plant known to contain and secrete a number of secondary metabolites that are toxic or a deterrent to herbivorous insects. Extractions specific to the leaf surface, the trichomes, and the laminar components demonstrated the localization of particular compounds. Diterpene glycosides occurred exclusively in leaf mesophyll, whereas nicotine was found in both the trichomes and mesophyll. Neither rutin nor nicotine was found on the leaf surface. Quercetin and 7 methylated derivatives were found in the glandular trichomes and appeared to be excreted onto the leaf surface. We examined the elicitation of these flavonols on the leaf surface with a surface-area allometric analysis, which measures changes in metabolites independent of the effects of leaf expansion. The flavonols responded differently to wounding, methyl jasmonate (MeJA), herbivore attack and UV-C radiation, and the response patterns corresponded to their compound-specific allometries. Finding greater amounts of quercetin on younger leaves and reduced amounts after herbivore feeding and MeJA treatment, we hypothesized that quercetin may function as an attractant, helping the insects locate a preferred feeding site. Consistent with this hypothesis, mirids (Tupiocoris notatus) were found more often on mature leaves sprayed with quercetin at a concentration typical of young leaves than on unsupplemented mature leaves. The composition of metabolites on the leaf surface of N. attenuata changes throughout leaf development and in response to herbivore attack or environmental stress, and these changes are mediated in part by responses of the glandular trichomes.     

The rare flavone isoetin as a yellow flower pigment in Heywoodiella oligocephala and in other Cichorieae

Isoetin (5,7,2′,4′,5′-pentahydroxyflavone) has been identified as a yellow flower pigment in Heywoodiella oligocephala, Hieracium pilosella and Hispidella hispanica. It also occurs in leaves of these plants and of 15 other taxa of the Cichorieae. It is restricted to three of the eight subtribes, occurring most characteristically in the Leontodontinae (in 5 of 7 genera surveyed). Isoetin is frequently accompanied by apigenin, luteolin, and scutellarein derivatives in these plants.     

The ultraviolet colour component enhances the attractiveness of red flowers of a bee-pollinated plant

蜂媒花很少呈红色,这可能是由于蜂类的眼睛缺少红光受体,因而较难搜寻红色目标。尽管有实验研究过蜂类对红色的反应,但所用目标多为纯红色。而人类感受到的红色中其实包含细微的色调差别,这些差别还甚少受到关注。我们在本研究中检验了如下假说：红花中的紫外反射组分能够增加其彩调反差,因而增强其对蜂类的吸引力。紫草科的密花滇紫草(Onosma confertum)由熊蜂传粉,其花为红色,但紫外反射明显。本研究利用该植物设计了表型操控实验,在野外检验了紫外反射对传粉者访花行为的影响。我们还在受控环境下检验了无经验熊蜂的色彩偏好。利用两个色彩模型评估熊蜂的色彩感受,用彩调反差和明度反差两个参数进行估计。研究发现,自然状态下及无经验的饲养熊蜂均偏好访问具有紫外反射的红色目标。色彩模型分析表明,具紫外反射的红花对蜂而言色彩更纯,且与叶片背景的彩调反差更大;而它们与无紫外反射的红花在明度反差方面(以绿光受体的反差估计)表现相似。这些结果表明,密花滇紫草红色花朵中的紫外反射组分增加了其彩调反差,增强了其对熊蜂的吸引力。我们推测,由于某些传粉者(例如蜂类)无红光受体,对由它们传粉的红色花而言,光谱中的副反射特征(例如紫外反射)可能是其花色中的必要组分。     

Pollination and fruit set in two rewardless slipper orchids and their hybrids (Cypripedium,Orchidaceae): large yellow flowers outperform small white flowers in the northern tall grass prairie

• Species with rewardless flowers often have low fruit to flower ratios, although wide temporal and spatial variation in fruiting success can occur. We compared floral phenotypes, insect visitors and fruiting success in four populations of the small white (Cypripedium candidum) and yellow (C. parviflorum) lady’s slipper orchids and their hybrids near the northern extent of North America’s tall grass prairie.
• Flower and fruit numbers were observed for two seasons on marked individuals (n = 1811). Floral traits were measured on 82–140 individuals per taxon and analysed in relation to fruiting success. All insects found inside flowers were collected, inspected for pollen smears and measured for comparison to floral features.
• Among orchid taxa, C. candidum had the smallest flowers, lowest number and variety of insect visitors, and lowest fruit to flower ratios. These measures were intermediate in hybrids and highest in C. parviflorum, despite low flower numbers in the latter. Within orchid taxa, fruit number was positively related to flower number, but fruit to flower ratios decreased slightly, as would be expected if pollinators left unrewarding patches. Potential pollinators included the dipteran Odontomyia pubescens and hymenopterans Andrena spp., Apis mellifera and Lasioglossum zonulum.
• Cypripedium parviflorum had a reproductive advantage over C. candidum across multiple populations and years. Hybrids showed segregation for floral traits, and hybrid fruiting success increased with a deeper intensity of yellow pigment and larger escape routes for floral visitors. These same attributes likely contributed to the relatively high fruit set in C. parviflorum in the study region.

     

A survey of leaf flavonoids in the portulacaceae

A survey of 26 species in 12 genera of the Portulacaceae showed the presence of flavonoids in 24, and their absence in two, Hectorella caespitosa Hooker fil. and Lyallia kerguelensis Hooker fil. Of the 24 positive species, 16 are reported for the first time. In all 24 however, flavonols and flavones did not occur together suggesting that this dichotomy might be useful for classification at and below the generic level in the Portulacaceae, e.g. the genera Silvaea Philippi (syn. Philippiamara Kuntze), Ceraria Pearson & Stephens and Portulacaria Jacquin which were previously grouped together on palynological characteristics have now been shown to differ in their leaf flavonoids, subsidiary cells of the stomata and geographical location: Silvaea possesses flavones and is endemic to South America, while Ceraria and Portulacaria possess flavonols and are endemic to Africa. The dichotomy also occurs below the generic level. In Calandrinia H.B.K. and Portulaca L. the dichotomy amongst their species is supported by other new taxonomic characters from cytology, palynology, pubescence of surfaces, type of subsidiary cells surrounding the leaf stomata and seed morphology recently elucidated by the author.     

Variations in flavonoid patterns within the genus Chondropetalum (restionaceae)

HPLC and chemical analyses of the flavonoids in culms of 11 Chondropetalum species divide the genus into two groups: seven, with glycosides of myricetin larycitin and syringetin; and four, with glycosides of kaempferol, quercetin, gossypetin, gossypetin 7-methyl ether and herbacetin 4′-methyl ether. This chemical dichotomy is correlated with anatomical differences and confirms the view that the genus requires taxonomic revision. HPLC measurements on those species with myricetin derivatives show that taxa with a qualitatively similar pattern of glycosides can be readily separated on quantitative grounds. Syringetin 3-arabinoside and a glycoside of herbacetin 4′-methyl ether are reported for the first time from the genus.     

Light absorption patterns of intact Rosa flowers in relation to the flower colour

Absorption curves of fresh, intact petals from 18 rose cultivars and 2 species were measured and compared with visual evaluations of their colours and there was a reasonable correlation. The in vivo maxima of anthocyanin absorption were in the range of 520–560 nm. Five patterns of absorption spectrum in the visible region were recognized: (a) maximum range ca. 520–535 rim (red roses); (b) as (a) but low absorbance (pink roses); (c) absorption pattern varying with age of flowers; (d) absorption at long wavelengths in blue roses due to co-pigmentation of cyanin, flavonols; (e) absorption of carotenoids and anthocyanins together in yellow, orange or orange red flowers.     

Neochilenin,a new glycoside of 3-O-methylquercetin,and other flavonols in the tepals ofNeochilenia,Neoporteria andParodia species (Cactaceae)

3-O-Methylated flavonols were isolated as crystals for the first time from the flowers ofNeochilenia, Neoporteria andParodia species belonging to the sub-family Cereoideae (Cactaceae), which are native to South America. The structures of three compounds were confirmed by chemical and spectral means. In the tepals of 7 species ofNeoporteria, 3-methyl ether of quercetin was found in the form of aglycone, whereas it was present as the 7-O-glucoside in the tepals ofParodia sanguiniflora and as the 4′-O-glucoside in the tepals of three species ofNeochilenia. Among those two glucosides of quercetin 3-methyl ether, the former has been found in a whole plant ofArtemisia transiliensis (Compositae), while the latter is new to the literature. Therefore, the term “neochilenin” may be assigned to this new pigment. Contribution from the Research Institute of Evolutionary Biology, No. 44.     

Evolution of honest reward signal in flowers

Some flowering plants signal the abundance of their rewards by changing their flower colour, scent or other floral traits as rewards are depleted. These floral trait changes can be regarded as honest signals of reward states for pollinators. Previous studies have hypothesized that these signals are used to maintain plant-level attractiveness to pollinators, but the evolutionary conditions leading to the development of honest signals have not been well investigated from a theoretical basis. We examined conditions leading to the evolution of honest reward signals in flowers by applying a theoretical model that included pollinator response and signal accuracy. We assumed that pollinators learn floral traits and plant locations in association with reward states and use this information to decide which flowers to visit. While manipulating the level of associative learning, we investigated optimal flower longevity, the proportion of reward and rewardless flowers, and honest- and dishonest-signalling strategies. We found that honest signals are evolutionarily stable only when flowers are visited by pollinators with both high and low learning abilities. These findings imply that behavioural variation in learning within a pollinator community can lead to the evolution of an honest signal even when there is no contribution of rewardless flowers to pollinator attractiveness.     

Phylogeny of Hypselodoris (Nudibranchia: Chromodorididae) with a review of the monophyletic clade of Indo-Pacific species, including descriptions of twelve new species

This work provides an account of the systematics and phylogeny of Hypselodoris . Aspects of the morphology of 42 species are described and the systematic status of an additional 11 species is discussed. Twelve new species are described: Hypselodoris alboterminata, H. bertschi, H. bollandi, H. fucata, H. iacula, H. insulana, H. krakatoa, H. paulinae, H. reidi, H. rudmani, H. violabranchia and H. zephyra. A phylogenetic analysis supports the monophyly of Hypselodoris and Risbecia . Two distinct clades of Hypselodoris are present. One contains species from the Atlantic and eastern Pacific while the other contains species limited to the Indo-Pacific tropics and adjacent temperate regions. Species from the Atlantic and eastern Pacific are bluish in body colour and have a plesiomorphically large receptaculum seminis while Indo-Pacific taxa are variably coloured and all have a minute receptaculum seminis. The distribution and size of mantle glands provides a wealth of morphological characters. With few exceptions, mantle glands vary in closely related species and are important for distinguishing members of smaller clades. Mantle gland distribution is therefore useful in identifying preserved material that is difficult to identify to species in the absence of the pigment of living specimens. Similar colour patterns found in sympatric species of Hypselodoris appear to be a result of both common descent and convergence between less closely related lineages. Biogeographic distributions of sister taxa provide several examples of vicariance. Examination of these cases shows that no single vicariant pattern is present, but vicariance appears to occur at the margins of the Indo-Pacific rather than centrally. Some vicariance occurs even within archipelagos such as the Hawaiian Islands. These cases largely refute the generality of the hypothesis of Springer (1982), that Pacific Plate and Australasian Plate endemic sister taxa should predominate.     

Evolution in the High Andes: The Phylogenetics of Muscisaxicola Ground-Tyrants

Phylogenetic relationships within the genus Muscisaxicola, a primarily Andean group of tyrant-flycatchers, were studied using complete sequences of the mitochondrial genes COII and ND3. Relationships among Muscisaxicola species were found to differ substantially from those of previous views, suggesting convergence in traditional avian taxonomic characters within the genus. The 11 species of large, gray, “typical” Muscisaxicola flycatchers (including M. grisea, newly restored to species status) formed a distinct clade, consisting of two major groups: a clade of 6 species breeding primarily in the central Andes and a clade of 5 species breeding primarily in the southern Andes. The other 2 species traditionally placed in this genus, M. fluviatilis, an Amazonian species, and M. maculirostris, were both rather divergent genetically from the typical species, although M. maculirostris may be the sister taxon to the typical clade. The patterns of sympatry exhibited by Muscisaxicola species in the high Andes appear to be the consequence of speciation and secondary contact within regions of the Andes, rather than a result of dispersal between regions. Diversification of the typical Muscisaxicola species appears to have occurred during the middle and late Pleistocene, suggesting generally that taxa of the high Andes and Patagonia may have been greatly influenced by mid-to-late Pleistocene events. There were likely several independent developments of migration within this genus, but migration is probably ancestral in the southern clade, with subsequent loss of migration in two taxa.     

Systematic implications of flavonoids and sesquiterpene lactones in species of Vernonia

Systematic and evolutionary interpretations based upon the distributional data for 27 flavonoids from 39 species and 9 sesquiterpene lactones from 38 species are presented for species of Vernonia mostly from the New World.     

Leaf flavonoids of Glycine subgenus Glycine in relation to systematics

A survey of leaf flavonoids and isoflavonoids in several taxa of the genus Glycne subgenus Glycine was undertaken to see if this would help interpret inter- and intraspecific relationships in the genus. C-Glycosylflavones based on apigenin were found in Glycine tomentelia, G. tabacina and G. falcata. Glycosides of quercetin and kaempferol were also detected in G. tabacina. In the cultivated soybean, G. max, and its wild annual relative, G. soja, only quercetin and kaempferol glycosides have been reported. Interspecific hybrids of Glycine species sometimes show additive flavonoid patterns in F₁ hybrid leaf tissue. All perennial wild species analysed including Glycine canescens and G. latifolia have the isoflavonoids genistin (genesitein 7-O-glucoside), daidzein and coumestrol in the leaves.     

Anthocyanin pigments and leaf flavonoids in the family araceae

Anthocyanins, variously identified in inflorescence, fruit, leaf or petiole of 59 representative species of the Araccae, are of a simple type. The most common pigment is cyanidin 3-rutinoside, while pelargonidin 3-rutinoside and cyanidin 3-glucoside are regularly present. Two rare pigments are: cyanidin 3-gentiobioside in Anchomanes and Rhektophyllum, both in the subfamily Lasioideae; and delphinidin 3-rutinoside in Schismatoglottis concinna. In a leaf survey of 144 species from 58 genera, flavone C-glycosides (in 82%) and proanthocyanidins (in 35–45%) were found as the major flavonoids. In the subfamily Calloideae, subtribe Symplocarpeae, flavonols replace glycoflavones as the major leaf components but otherwise flavonols are uncommon in the family (in 27% of the sample) and more usually co-occur with flavone C-glycosides. Two new flavonol glycosides were characterized from Lysichiton camtschatcense: kaempferol 3-(6-arabinosylgalactoside)and kaempferol 3-xylosylgalactoside. Simple flavones, luteolin and chrysoeriol (in 6%) were found only in the subtribes Arinae and Cryptocoryninae, subfamily Aroideae. Flavonoid sulphates were identified in only four taxa: glycoflavone sulphates in two Culcasia species and Philodendron ornatum and a mixture of flavone and flavonol sulphates in Scindapsus pictus. Caffeic ester sulphates were more common and their presence in Anthurium hookeri was confirmed. These results show that the Araceae are unusual amongst the monocots in their simple and relatively uniform flavonoid profile; no one subfamily is clearly distinguished, although at tribal level some significant taxonomic patterns are observed. The best defined groups are the subfamilies Lasioideae and Monsteroideae, and the tribes Symplocarpeae and Arophyteae, and the subtribe Arinae. The greatest chemical diversity occurs in Anthurium and Philodendron, but this may only reflect the fact that these are the two largest genera in the family. The origin and relationship of the Araccae to other monocot groups are discussed in the light of the flavonoid evidence.