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Abstract
Trees, treelets, shrubs or subshrubs, infrequently lianas or herbs, sometimes stoloniferous. Leaves alternate, sometimes opposite, distichous or pseudo-whorled, pinnately or rarely palmately veined, entire or rarely lobed or dissected, with conspicuous persistent or sometimes deciduous stipules, petiolate or sometimes subsessile, epulvinate; plants glabrous or variously pubescent with unicellular or multicellular hairs. Inflorescences thyrso-paniculate, botryoids (pseudo-racemes, compound or simple cymes), fascicles or condensed "short shoots", or flowers solitary; inflorescences subtended by a commonly persistent bract; pedicels commonly articulated, almost always bearing a pair of prophylls; flower buds in Viola and some other strongly zygomorphic genera becoming resupinate at anthesis, with saccate or spurred petal lowermost. Flowers bisexual (unisexual), actinomorphic to strongly zygomorphic, hypogynous (slightly perigynous); sepals 5, free, typically quincuncially arranged, persistent through fruiting, equal in actinomorphic flowers, slightly unequal or rarely strongly unequal in zygomorphic ones; petals 5, free, rarely persistent into fruit, equal in actinomorphic flowers, the anterior slightly to much longer and saccate or spurred in zygomorphic flowers, aestivation commonly apotact sensu Hekking (1988b), sometimes quincuncial or rarely convolute; stamens 5(3), free or filaments weakly to strongly connate into a tube; anthers dithecal, introrse, rarely extrorse, commonly bearing a dorsal sterile connective appendage, occasionally with two ventral connective appendages; in zygomorphic flowers 2 filaments and/or dorsal surfaces of the anthers bearing individual or fused nectariferous glands enclosed by a sac or spur at the base of a differentiated petal; ovary superior, (2)3(4–5)-carpellate, unilocular with parietal placentas; ovules 1–many, anatropous, bitegmic, crassinucellate; style filiform or sometimes clavate, straight, curved or sigmoid; stigma often simple, less often rostrate, orifice porrect or bent downward especially in zygomorphic flowers. Fruits commonly a capsule dehiscing with (2)3(4–6) coriaceous to woody, rarely elastic or papery valves, sometimes fleshy, rarely a nut. Seeds in most genera uniform, globose to narrowly ellipsoid, compressed to strongly flattened and often with an intermittent to entire wing in a few genera, rarely of two types (spindle-shaped and discoid), in some genera bearing elaiosomes; endosperm nuclear, oily; embryo flat, straight.
... Nevertheless, only a few studies were focused on Viola seeds (e.g. Gil-ad 1998;Colombo et al. 2007;Seo 2010;Ballard et al. 2014) and, usually, seed features are not considered as diagnostic characters to distinguish among species. ...
... This is in accordance with previous results for the Viola nuttallii complex, section Chamaemelanium (Fabijan et al. 1987), and for the section Viola (s.str.) (McPherson and Packer 1974), suggesting a trend toward the increase in pollen size with increasing chromosome number and with higher ploidy level (Fabijan et al. 1987;Ballard et al. 2014). For each parameter, the values followed by the same letter are not significantly different at the 5% level of probability, as determined by Tukey's test. ...
... Boreali-Americanae (W. Becker) Gilad (Gil-ad 1998) and in supporting the recognition of several phylogenetically distinct lineages currently lumped under the polyphyletic assemblage Hybanthus Jacq., also Violaceae (Seo 2010;Ballard et al. 2014). Many surface characters, even if of minor taxonomic importance, are often stable and can be of diagnostic significance when characterizing the lowest taxonomic categories or groups of related species, especially in small seeds (Barthlott 1981;Boesewinkel and Bouman 1995). ...
This integrated study provides new insights into pollen and seed morphology and pollen hetero-morphism of four closely related annual taxa of Viola sect. Melanium. The plant material, both fresh and dried, was collected in Italy and studied using light and scanning electron microscope. Palynological data for V. hymettia together with a detailed comparative analysis of seed morphology and micromorphology of the four species are reported for the first time. Results of this work highlight some pollen and seed features as useful diagnostic characters. The pollen size proves to be of diagnostic value to easily separate V. kitaibeliana, having the smallest pollen grains, from the others, especially from V. arvensis with the largest ones. Exine ornamentation is microreticulate, showing no relevant differences among species. We can partially confirm the diagnostic value of the prevailing pollen morph as it can be useful only for V. arvensis (five-aperturate) versus V. tricolor and V. hymettia (four-aperturate). The macro-and micromorphology of seeds provide additional useful distinguishing characters. Particularly, seed size was found to be a good delimitating character, especially to distinguish V. kitaibeliana (with the smallest
... The Violaceae is a cosmopolitan family that comprises roughly 1000-1100 species distributed among 22 genera (Ballard et al. 2014). Approximately half of the species of the family belongs to a single genus, the predominantly herbaceous Viola, which is widely distributed in the temperate Northern Hemisphere and high altitude areas of the Southern Hemisphere. ...
... Approximately half of the species of the family belongs to a single genus, the predominantly herbaceous Viola, which is widely distributed in the temperate Northern Hemisphere and high altitude areas of the Southern Hemisphere. The remaining 21 genera are restricted to warm subtropical or tropical regions of the world (except for a few species of Hybanthus s.l.), and they account for the great diversity of life forms and reproductive traits observed in the family (Ballard et al. 2014), including trees, shrubs, subshrubs, herbs and vines. The " lianescent clade " is an informal term that was coined from the results of recent phylogenetic studies (Feng 2005, Tokuoka 2008, Paula-Souza, 2009), to refer to a strongly supported clade that comprises all four lianescent genera in the family. ...
Violaceae is a cosmopolitan family comprising 22 currently
recognized genera and 1000-1100 species of trees, shrubs, subshrubs, herbs and vines, occupying a wide range of habitat types and regions around the world. Roughly half of the species in the family belong to a single genus, Viola, which is almost exclusively herbaceous and occurs in temperate and high altitude tropical zones. The remaining genera are confined to warm regions of the tropics and subtropics and exhibit the wide diversity of mostly woody growth forms previously mentioned. Independent phylogenetic studies based on molecular data have consistently grouped all the vines of the family together, converging to the recognition of a strongly supported "lianescent clade", which includes Agatea (ca. 8 spp.), from the South Pacific Islands, and the Neotropical Anchietea (7 spp.), Hybanthopsis (1 sp.) and Calyptrion (7 spp.). Apart from this intriguing disjunction which alone stimulates an interesting biogeographic discussion, the phylogeny of the Neotropical lianescent clade provides evidences for shifts between arid and humid habitats in the distribution of taxa throughout the group’s evolutionary history. In this context, the present study discusses the differentiation of an Amazonian/Mesoamerican moist forest lineage (Calyptrion) emerging from what now forms a characteristically SDTF endemic group (the South American Anchietea and Hybanthopsis), and further shifts in environmental preferences within the species of the latter, from dry, open conditions to water-related, forested habitats. Most of these shifts were found to be strongly associated with particular morphological features.
... Violaceae Batsch (Malpighiales) encompasses approximately 1100 species belonging to 26 genera, with the highest diversity in tropical areas (Stevens, 2001;Ballard Jr. et al., 2014;Wahlert et al., 2014). Viola L., Rinorea Aubl. ...
... Rinorea Aublet (1775: 235 & pl. 93) is a genus of about 280 species distributed across the tropics, with the majority of species growing in sub-Saharan Africa (Engler 1921, Taton 1969, Hekking 1988, Achoundong 2000, Ballard et al. 2014. Species of Rinorea are considered to be important bioindicators for forest typification as they are often locally abundant and different species of African Rinorea are characteristic for different forest types (Achoundong 1996, Adomou et al. 2006, Mwavu & Witkowski 2009, Tchouto et al. 2009, Djuikouo et al. 2010). ...
Rinorea calcicola, endemic to south-eastern Gabon, is described as a new species. Its most striking characteristic is the laminate fruit, a character so far only known for R. zenkeri. Rinorea calcicola has a limited distribution and appears to be restricted to limestone outcroppings. We have assessed it as endangered—EN B1ab(ii,iii,iv,v)—according to IUCN criteria. Morphological affinities of R. calcicola are discussed, and a key to R. zenkeri and the Gabonese species of Rinorea with textured fruits is given. The new species is one of many endemic species from the same region, and we recommend that a study of their distribution and ecology is undertaken to inform conservation planning. Because of the presence of so many narrow endemic species in the region, we suggest that the area be considered for protected status.
Over the course of revising the genus Rinorea (Violaceae) from Colombia, field observations and herbarium studies revealed seven new species. Several of the new species described here belong to species complexes that required examination of herbarium material from across the Neotropics. Each of the new species described here have oppositely arranged leaves and belong to Rinorea sect. Pubiflorae, a section restricted to the Neotropics. Two new species are segregated from the R. ovalifolia species complex: Rinorea chiribiquetensis from Chiribiquete National Park in the Colombian Amazon and Rinorea stevensii from the Orinoco River near the border of Colombia and Venezuela. Two new species are segregated from the Rinorea hirsuta species complex: Rinorea galeanoae-bernalii and Rinorea cogolloi, both from the eastern slopes of the Andean Central Cordillera along the mid-Magdalena River Valley in Colombia. From the widely distributed R. pubiflora species complex, we segregated one new species, Rinorea callejasii, from southeast Panama and the Chocó in Colombia. In addition to these five new taxa segregated from widely distributed species complexes, we discovered two previously unknown species with affinities to other Neotropical Rinorea. Rinorea aymardii is described from the Alto Orinoco-Casiquiare Biosphere Reserve in Venezuela and most closely resembles R. melanodonta from Colombia. Rinorea betancurii is segregated from R. macrocarpa and occurs in the Amazonian Regions of Colombia, Brazil, Peru and Venezuela. In this study, we provide descriptions, illustrations and distribution maps of the new species and make preliminary assessments of the risk of extinction using the IUCN Red List Categories and Criteria. We also furnish an identification key to the species of Rinorea sect. Pubiflorae in Colombia.
Abstract. A taxonomic treatment is presented for the violets (Violaceae) confirmed in the range described in the
second edition of Gleason and Cronquist’s Manual of Vascular Plants of Northeastern United States and Adjacent
Canada, in advance of the new treatment of this manual that is in preparation. Recent field, herbarium, and laboratory
investigations of eastern North America’s violet flora by the author and students have reexamined eastern North
American violet taxa and utilized multiple sources of evidence filtered through modern species concepts to delimit taxa
and assign appropriate taxonomic rank. Results have led to the recognition of 58 native and eight introduced species,
one subspecies, one variety and one form, 10 informal variants, and 113 wild hybrids in our region, representing the
genera Cubelium, Pombalia, and Viola. In Viola, two new species are described and three new combinations are made
(one to species rank, one to subspecies, and one to forma), and eight names are typified. Viola taxa are distributed across
five sections and nine subsections and are representative of most of the infrageneric taxonomic diversity in North
America overall. Anomalous variants in Viola emarginata, Viola palmata, Viola septentrionalis, and Viola sororia
currently lack sufficient information for taxonomic decisions but are presented to encourage study, collection, and
documentation. Six potential taxa occur adjacent to or very near our region and may eventually be discovered in our
area; they are included in the keys and briefly described with figures. The treatment includes introductory text,
dichotomous keys, synonymy with some type information, detailed descriptions, and other information, as well as color
figures of habit and plant structures and US county-level geographic distribution maps for nearly all included taxa.
The study aims are to examine the characteristics of artificial and natural hybrids between Viola albida var. albida (= albida , from below) and V. albida var. chaerophylloides (= chaerophylloides , from below), and to confirm if hybrids could be fertile and make populations in their native habitats. The 1st filial (= F<sub>1</sub>, from below) leaf shape produced by artificial crossing between albida and chaerophylloides was the same as that of V. albida var. takahashii (= takahashii , from below), and F<sub>1</sub> bore also both chasmogamous and cleistogamous flowers. F<sub>1</sub> seed number was 9.6 per cleistogamous pods, which was remarkably less than the average of 38.2 for albida and chaerophylloides , but the germination rate was all similar. The leaf type of self-crossed 2nd offsprings (= F<sub>2</sub>, from below) showed all leaf types found in the Viola albida complex, but the ratio of chaerophylloides leaf type was relatively low. Individuals whose F<sub>2</sub> leaf type was restored to albida produced an average of 31.4 seeds per capsule, meaning that fertility was restored. On the other hand, individuals of F<sub>2</sub> takahashii leaf type come to fruition a low average of 10.4 seeds per capsule, which is similar to that of takahashii . The results of crossbreeding experiment, where is their native habitats, were similar to that of laboratory. Both albida and chaerophylloids in Mt. Bulmyeong distribute extensively, but takahashii make a small population only in places where albida and chaerophylloides grow together. Summarizing the above results is suggesting that the speciation of takahashii was done by hybrid between albida and chaerophylloides , and these have been maintained with relatively small population by cleistogamous capsules.
Viola is a large genus with worldwide distribution and many traits not currently exemplified in model plants including unique breeding systems and the production of cyclotides. Here we report de novo genome assembly and transcriptomic analyses of the non-model species Viola pubescens using short-read DNA sequencing data and RNA-Seq from eight diverse tissues. First, V. pubescens genome size was estimated through flow cytometry, resulting in an approximate haploid genome of 455 Mbp. Next, the draft V. pubescens genome was sequenced and assembled resulting in 264,035,065 read pairs and 161,038 contigs with an N50 length of 3,455 base pairs (bp). RNA-Seq data were then assembled into tissue-specific transcripts. Together, the DNA and transcript data generated 38,081 ab initio gene models which were functionally annotated based on homology to Arabidopsis thaliana genes and Pfam domains. Gene expression was visualized for each tissue via principal component analysis and hierarchical clustering, and gene co-expression analysis identified 20 modules of tissue-specific transcriptional networks. Some of these modules highlight genetic differences between chasmogamous and cleistogamous flowers and may provide insight into V. pubescens’ mixed breeding system. Orthologous clustering with the proteomes of A. thaliana and Populus trichocarpa revealed 8,531 sequences unique to V. pubescens, including 81 novel cyclotide precursor sequences. Cyclotides are plant peptides characterized by a stable, cyclic cystine knot motif, making them strong candidates for drug scaffolding and protein engineering. Analysis of the RNA-Seq data for these cyclotide transcripts revealed diverse expression patterns both between transcripts and tissues. The diversity of these cyclotides was also highlighted in a maximum likelihood protein cladogram containing V. pubescens cyclotides and published cyclotide sequences from other Violaceae and Rubiaceae species. Collectively, this work provides the most comprehensive sequence resource for Viola, offers valuable transcriptomic insight into V. pubescens, and will facilitate future functional genomics research in Viola and other diverse plant groups.
During the revision of Viola for the Flora of Argentina project we detected names which need an exhaustive nomenclatural and taxonomic study. As a result of our analysis 43 lectotypes and three neotypes are designated for accepted names and synonyms of the genus as currently recognised by the present authors. Moreover, we encountered a nomen nudum, and present here a new combination and five new synonyms.
A new species of Violaceae, Decorsella arborea Jongkind, is described and illustrated. The new species differs from the only other species in the genus, D. paradoxa A. Chev., by the larger size of the plants, smaller leaves, more slender flowers, and stamen filaments that are free for a much larger part. Both species are from the Guineo-Congolian forest of tropical Africa. The differences between Decorsella and Rinorea are discussed. Confirming recent reports, some species of Rinorea can have zygomorphic flowers and some of these can be almost equal in shape to Decorsella flowers.
Citation: Jongkind C. C. H. 2017: Decorsella arborea, a second species in Decorsella (Violaceae), and Decorsella versus Rinorea. — Willdenowia 47: 43–47. doi: https://doi.org/10.3372/wi.47.47105
Version of record first published online on 13 February 2017 ahead of inclusion in April 2017 issue.
Rinorea callmanderi Wahlert (Violaceae), a new species from northwestern Madagascar, is described and illustrated. This new species was discovered during an intensive floristic inventory in the botanically unexplored Kalabinono and Galoko massifs. Based on morphological and molecular evidence, the new species is placed in Rinorea subsection Verticillatae Engl., the most species-rich group of Rinorea Aubl. in Madagascar. Rinorea callmanderi is morphologically most similar to Rinorea mutica (Tul.) Baill. by its opposite-leaved phyllotaxy and condensed, subsessile cymose inflorescence, but differs by the shape and size of the leaf, the pattern of pubescence on the inner surface of the petal, and the presence of dorsal and ventral anther connective scales. The new species is described and provided with line drawings, a distribution map, a discussion on its morphology, and a preliminary conservation assessment using the IUCN Red List Categories and Criteria.
Rosidae, a clade of ∼ 90 000 species of angiosperms, exhibits remarkable morphological diversity and extraordinary heterogeneity in habitats and life forms. Resolving phylogenetic relationships within Rosidae has been difficult, in large part due to nested radiations and the enormous size of the clade. Current estimates of phylogeny contain areas of poor resolution and/or support, and there have been few attempts to synthesize the available data into a comprehensive view of Rosidae phylogeny. We aim to improve understanding of the phylogeny of Rosidae with a dense sampling scheme using both newly generated sequences and data from GenBank of the chloroplast rbcL, atpB, and matK genes and the mitochondrial matR gene. We combined sequences from 9300 species, representing 2775 genera, 138 families, and 17 orders into a supermatrix. Although 59.26% of the cells in the supermatrix have no data, our results generally agree with previous estimates of Rosidae phylogeny and provide greater resolution and support in several areas of the topology. Several noteworthy phylogenetic relationships are recovered, including some novel relationships. Two families (Euphorbiaceae and Salvadoraceae) and 467 genera are recovered as non-monophyletic in our sampling, suggesting the need for future systematic studies of these groups. Our study demonstrates the value of a botanically informed bioinformatics approach and dense taxonomic sampling for resolving rosid relationships. The resulting tree provides a starting point for large-scale analyses of the evolutionary patterns within Rosidae.
A new species Afrohybanthus indicus is described and illustrated. It differs from A. stellarioides and A. enneaspermus in the characters of stipule, leaf margin and pedicel.
Resupination, i.e., the turn by 180°, arranges zygomorphic flowers in a suitable position for pollination. It is well-known from orchids, but also occurs in further angiosperm families. Within the genus Thalia L. (Marantaceae), T. dealbata has erect and T. geniculata pendulous inflorescences. Nevertheless, in both species the zygomorphic flower-pairs show the right position for pollination. Thus, resupination is expected in Marantaceae. To reconstruct spatial arrangement, flower development was investigated from meristem formation to anthesis. Early morphogenetic stages were analysed under the scanning electron microscope, late stages were documented by time-lapse records. Gravity experiments were added to test for plastic or genetically fixed flower-pair position. Flowers in both Thalia species develop almost identically. They originate from a common primordium and show the unusual floral organ sequence already described for the family. In T. dealbata, the flower-pair gets its final position by bending 90° backwards, while in T. geniculata a lateral rotation of 90° takes place shortly before anthesis. In both species, position is genetically fixed. Results clearly indicate that the flower-pairs in Thalia do not show resupination according to the given definition. Instead of the expected 180° turn in one species, flower-pairs in both species each dislocate for 90°.
Recent traditional and molecular systematic studies of the violet family, Violaceae, have confirmed extensive polyphyly of the genus Hybanthus and substantial polyphyly in Rinorea as well. Phylogenetic analyses have proposed up to nine distinct hybanthoid clades. Broad studies of representative taxa within each clade have revealed coherent suites of macromorphological traits in foliage, flowers, fruits and seeds that easily discriminate the nine hybanthoid lineages from each other and from currently recognized genera in the family. Base chromosome numbers and biogeography also provide additional support for recognition of the hybanthoid clades as distinct segregate genera. Some hybanthoid clades have available older generic names, but one of the two Old World lineages, namely the Hybanthus enneaspermus group, is presently nameless. This clade, distinctive in its ellipsoid, pale yellow, often foveolate seeds, is the most diverse in the Paleotropics, with approximately 25 species distributed across Africa, Madagascar, southern Asia, northern Australia and the southwestern Pacific. The group is segregated here as Afrohybanthus gen.ov., with new combinations provided for existing names, all of which have thus far proven morphologically distinct and worthy of recognition at the rank of species. Imminent future studies will describe additional taxa in the new genus.
Ixchelia, a new genus of Violaceae, is described and illustrated, and new combinations are made for its two species, Ixchelia mexicana and Ixchelia uxpanapana, which are transferred from Hybanthus and Rinorea, respectively. In previous molecular phylogenetic studies, both Hybanthus and Rinorea have been shown to be polyphyletic, necessitating the erection of several genera for the constituent clades. Our recognition of Ixchelia as a distinct genus is based on morphological data and molecular phylogenetic evidence, both of which support its monophyly and its significant divergence from related genera. The new genus is most closely related to the Hawaiian endemic genus Isodendrion and the New World genus Pombalia, but it differs from them by having one to several flowers per inflorescence, a weakly zygomorphic corolla, the basal portion of the petals not fused, the stamen filaments fused into a tube, and the fruits containing three subspherical-ovoid seeds per capsule.
A new species of Paypayrola from a white sand savanna in the San Miguel river basin, a tributary of the lower Guainía river in Amazonas State, Venezuela, is described, illustrated, and its relationships with putatively allied species are discussed. This new species differs from all others in the genus in its small habit and aggregate life-form. The flowers are similar to those of P. confertiflora and P. blanchetiana but are intermediate in size and the petals are pink- or red-tinged. The phytogeography of white sand savannas is briefly discussed and a key and a synopsis of the known species of Paypayrola are presented in two appendices. Leaf structure and histology were studied using both light and scanning electron microscopy and a chemical test showed a positive reaction to aluminum accumulation in leaf tissues. However, it was not possible to ascertain if levels of aluminum accumulation exceeded what was present in the substrate.
Abstract—
Rinorea is a pantropical genus of shrubs and small trees within the family Violaceae. The genus is particularly diverse in Africa where species are ecologically important as they are often abundant or even dominant in particular forest types and act as larval
host plants for highly specialized Cymothoe butterflies. Despite their importance, species identification of African Rinorea is difficult and a taxonomic revision is needed. Previous phylogenetic studies have suggested that neotropical taxa are sister to a palaeotropical clade,
with multiple independent dispersals to Madagascar, but these were based on plastid data only. We therefore present an updated phylogeny of Rinorea with increased sampling of African taxa, using plastid as well as nuclear DNA sequences. Phylogenetic relationships inferred from nuclear
DNA data were generally congruent with those based on evidence from plastid haplotypes from earlier studies. Our increased taxonomic sampling also revealed previously undiscovered African Rinorea clades, some of which warrant further taxonomic study. Ancestral state reconstructions
refute previous hypotheses about the evolution of morphological characters traditionally used for Rinorea infrageneric classification. In addition, some widespread species may comprise species complexes. It is clear that African Rinorea require comprehensive taxonomic revision;
our contribution to understanding Rinorea infrageneric relationships will facilitate this task.
Recent taxonomical studies on South American Hybanthus s.l.
attest the occurrence of Hybanthus lanatus (A. St.-Hil.) Baill.
(Violaceae) in Argentina, altough this species has been previously reported as endemic to the Cerrado of the Brazilian
Plateau. This species presents large morphological variations
within its distribution range. It is part of Hybanthus lanatus
complex which includes 5 other species phylogenetically
closely related (Hybanthus poaya (A. St.-Hil.) Baill., Hybanthus
strigoides Taub., Hybanthus velutinus Schulze-Menz and
two other undescribed species). Hybanthus velutinus Schulze-
Menz had been recorded in Argentina in the 1950’s, but this
occurrence is based on an incorrect identification of specimens
collected in San Ignacio, in the very same area where Hybanthus
lanatus has been recorded. The disjunct distribution of Hybanthus lanatus between the Brazilian Plateau and the area
of San Ignacio in Argentina, further supported by similar cases
in other plant groups, suggests a dispersal model rather than a «dry forest refuge» model event. Descriptions, comments on the geographical distributions and illustrations of Hybanthus lanatus and Hybanthus velutinus, are provided in order to eliminate future confusion between these two species.
Rinorea is the second most species-rich genus in the Violaceae and has a pantropical distribution. In this study we investigated relationships among species of Rinorea and tested the monophyly of newly revised infrageneric groupings of African and Malagasy species. Phylogenetic inference was based on maximum parsimony, maximum likelihood, and Bayesian analyses of plastid trnL/trnL-F and trnD-trnE regions. Results showed the divergent Neotropical Rinorea 'Apiculata' group to be a strongly supported clade which was consistently resolved outside of the Rinorea s. s. clade. The Rinorea s. s. clade was strongly supported and was comprised of Neotropical and Old World clades. The Old World clade was strongly supported and contained 11 clades that corresponded to newly revised infrageneric groupings of African and Malagasy species. An additional Old World clade was recovered which contained all Asian species sampled in the study and was resolved as sister to the Malagasy endemic Rinorea subsect. Verticillatae. Maximum parsimony analysis recovered two Neotropical clades, while maximum likelihood and Bayesian analyses recovered a weakly supported monophyletic Neotropical clade. This study represents the first estimation of the phylogeny of Rinorea with sampling across its distribution and breadth of morphological diversity. The results presented here have implications for generic limits in Rinorea, infrageneric taxonomy of the African and Malagasy species, and biogeography of Rinorea in Madagascar.
Few studies have examined insects visiting flowers of tropical Violaceae. This study presents results from field work in Ivory Coast and from the examination of cultivated plants of three species in the two largest tropical genera, Rinorea and Hybanthus. Field observations showed that Hybanthus enneaspermus flowers opened only one morning and were visited by a single bee species. In contrast, the two species of Rinorea observed, which have flowers that do not close, were visited by many and various insects. Cultivation showed that self-pollination, with viable seeds production, appears likely in H. enneaspermus, perhaps as a means of compensating for the possible scarcity of pollinators. Floral structures would support allogamy first, and then lead to autogamy.
We present the first pollination data on Neotropical species of Violaceae with actinomorphic flowers. Floral biology of Paypayrola blanchetiana and Amphirrhox longifolia were studied in Brazilian Atlantic rainforest. Petals of both species form a corolla tube, restricting access to floral rewards to visitors with long mouth parts. Flowers lack a spur, common in zygomorphic Violaceae, to store nectar. Both species’ flowers open in the evening and continue flowering during daytime. They emit a sweet scent dominated by benzenoid and monoterpenoid compounds. While A. longifolia flowers are nectarless, flowers of P. blanchetiana produce nectar throughout anthesis. A wide range of night- and day-active visitors, including moths, bees, and butterflies, were observed at P. blanchetiana; 68% of all nocturnal visits took place at dawn. Fruit set of P. blanchetiana was extraordinarily low. Nectar production and pollen presentation occur in close proximity, and pollen dissolves in accumulating nectar. After contact with nectar, experimental pollen germination rates were near 0. Amphirrhox longifolia flowers received few visits by diurnal and nocturnal bees and pollen-collecting Heliconius butterflies. Fruit set was still low (11%) but was ten times higher than that in P. blanchetiana (1%). Low fruit set seems to result from diminished pollen viability through nectar contact in P. blanchetiana and pollinator limitation in A. longifolia.
This study investigates the effect of high concentrations of Pb and Zn on biomass production and accumulation of both metals in zinc violets (Viola calaminaria and Viola guestphalica) and two species of violets indigenous to Poland (Viola lutea sudetica and Viola tricolor). The influence of the plants on soil pH also was assessed. The soil used in the experiments, containing 183 mg kg-1 Zn and 53.4 mg kg-1 Pb, was spiked with Zn and Pb at 1000 mg/kg soil (Treatment 1) or Zn at 10,000 mg/kg and Pb at 1000 mg/kg (Treatment 2). Zn concentrations tested higher in roots than in shoots in all investigated species. In zinc violets, a Zn content in the soil correlated with Zn concentrations in plant tissue, both roots and above-ground parts. There was no such dependence among indigenous violets. Since all confirmed hyperaccumulators accumulate metals preferentially in shoots, with lower concentrations in roots, our results suggest that zinc violets should not be classified as Zn hyperaccumulators. V. l. sudetica occurs naturally on soils with low heavy metals content. Its roots accumulated the highest amount of Zn (6498 mg/kg) observed in the current study with no toxic effects. Roots were able to change the soil pH, but the differences were not significant. V. l. sudetica and V. tricolor increased biomass significantly in Treatment 1 versus the control, but in Treatment 2 neither species differed in biomass from the control. In Viola guestphalica no influence of treatments on dry weight was observed. The results suggest that zinc violets should not be treated as zinc hyperaccumulators. We suggest that zinc violets can be useful for phytorestoration of contaminated sites.
A new genus of arborescent violet, Hekkingia, is described from Neotropical lowland rainforest near Cayenne
in northeastern French Guiana. Racemose inflorescences, fully fused filaments and rudimentary dorsal connective appendages place the only known species, Hekkingia bordenavei, near the genus Paypayrola, while strongly tuberculate capsules ally it also to Amphirrhox, the two genera comprising the Subtribe Paypayrolinae to which the new genus is tentatively assigned. Hekkingia shares scarcely differentiated corollas with quincuncial aestivation, very large obovate sepals, red to pink capsules and carunculate seeds with few other genera (but not in this combination), whereas its basally cauliflorous habit, very large bracts and pedicel bractlets are unique in the family. A key to genera of the Violaceae provides a context for this French Guianan novelty.
The Violaceae consist of 1,000–1,100 species of herbs, shrubs, lianas, and trees that are placed in 22 recognized genera. In this study we tested the monophyly of genera with a particular focus on the morphologically heterogeneous Rinorea and Hybanthus, the second and third most species-rich genera in the family, respectively. We also investigated intrafamilial relationships in the Violaceae with taxon sampling which included all described genera and several unnamed generic segregates. Phylogenetic inference was based on maximum parsimony, maximum likelihood, and Bayesian analyses of DNA sequences from the trnL/trnL-F and rbcL plastid regions for 102 ingroup accessions. Results from phylogenetic analyses showed Rinorea and Hybanthus to be polyphyletic, with each genus represented by three and nine clades, respectively. Results also showed that most intrafamilial taxa from previous classifications of the Violaceae were not supported. The phylogenetic inferences presented in this study illustrate the need to describe new generic segregates and to reinstate other genera, as well as to revise the traditionally accepted intrafamilial classification, which is artificial and principally based on the continuous and homoplasious character state of floral symmetry.
The flower structure, pollination, sex expression, and some secondary sex characters of Melicytus lanceolatus, M. ramiflorus, and M. micranthus are described. All three species are strictly dioecious. Male-biased sex ratios occur in M. lanceolatus and M. ramiflorus. There is a marked contrast in flower structure between M. lanceolatus and the other two species. In M. lanceolatus, as in most species of the Violaceae, the pollen is concealed by apical appendages of the anther connectives and fusion along the edges of adjacent anthers. Nectar is concealed within purple petals. In the flowers of M. ramiflorus and M. micranthus, the anthers are free and the apical appendages are much reduced, so the pollen is exposed. The petals are white or yellow and are recurved, exposing the nectaries. M. lanceolatus represents the more primitive condition, and the other two species show a loss of specialisation of flower structure, the reverse of the usual trend in floral evolution in the angiosperms. The three species are insect pollinated. A variety of insect species visit the flowers of M. lanceolatus and M. ramiflorus. Syrphids are the only insects which visit flowers of both sexes of M. micranthus. Foraging behaviour of most insect species on the flowers is unsystematic. Fruit of all species are adapted for animal dispersal and two species of birds were seen feeding on berries of M. ramiflorus.
Structure of inflorescences and flowers and flowering behaviour are reported for the woody liana Anchietea pyrifolia (Violaceae) from Brazil. The specimen studied is grown for some decades now in the greenhouses of Halle Botanical Garden and turned out unisexually male, which adds a further example of dioecism to the family Violaceae, in which this type of sex distribution is rarely encountered. The flowers are exceptional also for the strongly asymmetric anterior petal, which represents a rare case of a species with enantiomorphic flowers pollinated by Lepidoptera. They have a fully developed gynoecium with a complicated architecture comparable to the pistil of bisexual Violaceae flowers, though without ovules. The style head is capable to release viscose liquid on tactile stimulation or pressure, which is known to act as pollen-gathering mechanism in bisexual Violaceae species with usually dry pollen and buzz-pollination. This function has switched in male A. pyrifolia to a mechanism for efficient pollen release mediated by insect pollinators from its short-lived flowers.
Few studies of inbreeding depression have focused on species producing both showy, chasmogamous (CH) flowers and self-pollinated, cleistogamous (CL) flowers. The goals of this investigation were to measure the level of inbreeding depression in the North American violet, Viola canadensis L., and to determine if any fitness differences were linked to floral type (CH versus CL) rather than to cross type (self versus outcross). Hand pollinations were carried out to produce self- and outcross-pollinated CH progeny, and CL seeds were also collected. In a greenhouse, selfed and outcrossed CH flowers produced similar numbers of seeds, and both types of progeny had similar survival rates and comparable numbers of CH flowers, although outcrossed CH progeny had 14% greater vegetative biomass than selfed CH progeny. The level of inbreeding depression in V. canadensis was low, indicating that there may be few drawbacks to selfing in this species. A comparison of CL and self-pollinated CH progeny showed that, although there were differences in CH flower number, overall fitness differences were minimal. The similar performance of selfed (CL and CH) and outcrossed progeny in early life-history stages of V. canadensis suggests a history of inbreeding in the population.Key words: cleistogamy, inbreeding depression, outcrossing, selfing, Viola canadensis.
Elemental concentrations were studied in two New Caledonian hyper-accumulators of nickel and in the soils supporting these plants. The nickel content of Hybanthus austrocaledonicus was directly related to the total nickel content of the soil, and this species may therefore be used for biogeochemical prospecting. Nickel was correlated well with other elements of the iron family in non-lateritic ultrabasic soils but not in laterites. Both H. austrocaledonicus and Homalium kanaliense contained adequate amounts of potassium despite very low concentrations in the supporting soils. These low nutrient levels were further aggravated by antagonism to potassium uptake caused by other soil elements. Because of the paucity of relationships between nickel in H. kanaliense and elements in the soil, it is suggested that the high nickel levels in this plant may be controlled by organic constituents in this species. re]19760504
Viola subsection Boreali-Americanae (Violaceae), confined to North America including northern Mexico, has long been considered one of the most taxonomically difficult temperate groups of the Angiosperms. Hybridization, followed in some localities by introgression, has made it difficult for systematists to discern the core species by using only standard macromorphological characters. Analyses that employed Scanning Electron Microscopy (SEM) of seed coats and petal trichomes generated new characters. SEM of the surface of seeds of each of the orthospecies revealed a suite of primary and secondary sculpture characters unique to each species that are correlated with a suite of macromorphological characters. In a number of species, SEM of petal trichomes provided additional unique characters. SEM of the surface of seed coats enabled the identification of instances of hybridization by revealing blends of structures of the primary and secondary sculpture typical of different orthospecies and instances of putative introgression by revealing deviations from the structures typical of the orthospecies. A procedure based on iterative examinations of macromorphology and micromorphology, which was developed in this research, enabled the discernment of hybrids and putative introgressed taxa and the evaluation of the macromorphological characters of the taxa of the subsection. Combining the micromorphological and macromorphological data with ecological and phytogeographical data enabled the delimitation of the orthospecies. PAUP version 3.1.1 was utilized on a data set composed of 59 macromorphological and cytological characters to reconstruct the phylogeny of Viola subsection Boreali-Americanae. The resulting highly resolved cladograms established the monophyly of the subsection and enabled the generation of hypotheses on the evolutionary relationships of the North American species of Viola and a number of outgroup taxa and hypotheses on character evolution. Sixteen taxa are circumscribed as orthospecies: Viola affinis LeConte, V. brittoniana Pollard, V. cucullata Aiton, V. egglestonii Brainerd, V. fimbriatula Sm., V. missouriensis Greene, V. nephrophylla Greene, V. novae-angliae House, V. nuevoleonensis W. Becker, V. pedatifida G. Don, V. sagittata Aiton, V. septemloba LeConte, V. septentrionalis Greene, V. sororia Willd., V. triloba Schwein., and V. villosa Walter. Two changes of rank are proposed: Viola brittoniana Pollard forma pectinata (Bicknell) Gil-ad and Viola novae-angliae House subsp. grisea (Fernald) Gil-ad. New descriptions of the characters delimiting Viola subsection Boreali-Americanae and each of its orthospecies, keys to the orthospecies at the chasmogamous and cleistogamous phases, and discussions of names that are commonly recognized as orthospecies, but are hypothesized in this research to represent hybrids or introgressants, are provided. A lectotype is designated for Viola subsection Boreali-Americanae. The type specimens of 15 of the 18 taxa recognized in this research have been located. Viola affinis, and V. septemloba are lectotypified by illustrations.
Surveys of Viola dispersal mechanisms result in the distinction of two major adaptive syndromes: one purely myrmecochorous for the exploitation of seed-transporting ants, the other partially myrmecochorous (= diplochorous) for the explosive ejection of seeds followed by ant exploitation. Diplochory is exhibited by the majority of Viola species, but myrmecochory is exhibited only by eleven species with limited Eurasian distribution. Morphological and experimental evidence suggests the hypothesis that Viola is basically myrmecochorous but that different selective pressures, especially seed predation, have produced a clear divergence in dispersal systems. The majority of species, the diplochores, have evolved a system which combines ballistic and ant seed dispersal with predator avoidance. Diplochory itself may be a response to predation pressure. The minority of species are purely myrmecochorous, possibly highly coevolved with specific ant species, thus limiting the distribution of the Viola species concerned.
In Viola odorata, chasmogamous (CH) or open flowers and small, short-petioled leaves are produced under 11 hr or less of daylight, cleistogamous (CL) or closed flowers and large, long-petioled leaves under 14 hr or more of daylight, and intermediate floral and leaf forms under transitional photoperiods. CL flowers are approximately four times smaller than CH flowers and differ morphologically in repressed growth of the anterior petal spur and staminal nectaries, and recurving of the style which remains enclosed within the cone formed by anther appendages. Both CH and CL shoot systems conform to a (2 + 3) phyllotaxis with minor differences in leaf divergence angles and phyllotactic indices. The larger CL leaf grows significantly faster than the CH leaf, and an increased rate of leaf initiation occurs in the CL apex represented by a plastochron of 3.4 days compared to 4.3 days in the CH apex. The plastochron index was used to indirectly age young floral primordia nondestructively until prophase of meiosis I within the anthers. This event occurs 8 days earlier in the CL than the CH flower. Time from meiosis until flower maturity, determined by direct observation, is about 14 days for the CL flower, versus 21 days for the CH flower.
There exist three different kinds of leaf arrangement in neotropical species of Rinorea.
Recent work suggests that Fusispermum Cuatrec. and Rinorea Aubl. form small clades that are sister to the rest of the Violaceae and that the Goupiaceae is sister to the Violaceae. However, little is known about the morphology and anatomy of these phylogenetically critical groups. In this paper I present aspects of the morphology and anatomy of stem, node, leaf, flower, and seed of three species of Fusispermum and seven species of Rinorea, as well as Goupia glabra Aubl. (Goupiaceae), which is the outgroup. Placing this variation in the context of hypothesized phylogenetic relationships, I found Fusispermum to have unique pentalacunar nodes, heterogeneous pith, and elongated seeds, while Goupia Aubl. has a unique 5-carpellate gynoecium with marginal styles and a tegmen with U-shaped thickenings. Furthermore, variation in androecium and nectary links the distinctive androecium so common in the Violaceae with more conventional structures found in other taxa of the parietal placentation group of Malpighiales. Strengthening our basic knowledge of anatomy and morphology in these groups is an essential prerequisite for understanding the evolution and diversification not only of Violaceae but of Malpighiales as a whole.
Pollination in Viola results both from sternotribic and nototribic pollinator responses, the frequencies of which vary according to the plant species. Syndromes of floral characters determine these frequencies, and each is adaptive to a group of pollinators, of variable taxonomic heterogeneity, characterised by particular morphology and behavior. Some syndromes elicit equal frequencies of sterno- and nototribic responses, while others elicit chiefly, or exclusively, one type, and coevolution with a single msect genus may be in progress. One effect of the differing syndromes is the partitioning of pollinator resources among simultaneously flowering species. An evolutionary sequence for the floral syndromes is proposed which, in broad agreement with systematic conclusions, considers yellow-flowered, sternotribic Chamaemelanium violets as the most ancient and blue-flowered sterno- or nototribic violets of the sections Rostellatae and Plagiostigma as the most recently evolved. Species of the section Melanium (the pansies), in which cleistogamy is almost absent, appear to be an early offshoot leading to multicolored, nototribic flowers. The "generalist" syndromes were probably vital to the success of the genus in (a) invading the northern and southern temperate zones and (b) adapting to widespread habitat disturbance by man. The basic structure of the violet flower is adaptive to a temperate pollinator complex to be found over very large geographic areas. Floral variations demonstrate adaptive radiation to many ecological conditions.
Allexis zygomorpha, a new species from the littoral forest of Cameroon is described.
Geobotanical and biogeochemical investigations undertaken in Western Australia have shown that the presence of unusual shrub communities is related to concentrations of toxic elements, particularly nickel, copper and chromium in the soil, in some cases emanating from nickel sulphides in bedrock. They have distinguished anomalies due to nickel concentrations from those due to chromium concentrations and have established the species associated with each. They have disclosed Hybanthus floribundus as a nickel accumulator which together with Trymalium myrtillus and Dodonaea microzyga may be indicative of a nickeliferous environment, especially a combination of low pH and high available nickel in the soil which may emanate from nickel sulphides. It has been shown that geobotany is of only limited assistance in areas where there is deep cover or abundant calcium carbonate in the soil. With the exception of Hybanthus floribundus, the metal content of most plant species is low but biogeochemical anomalies do occur over mineralized bedrock. The resinous nature of many plants is a complicating factor for both geochemistry and biogeochemistry. Thus geobotany and biogeochemistry can assist in exploration for nickel in the winter rainfall environment of Western Australia. The complex relationships between plant distributions and relief and drainage conditions, the presence of laterite and of transported cover from several weathering cycles and the occurrence of several rock types of similar chemical composition producing very high background nickel and chromium levels in the soil, however, necessitate careful interpretation of geobotanical data. Likewise careful assessment of biogeochemical data is essential because the sclerophyllous nature of the leaves of most tree and shrub species is associated with limited uptake of metals and biogeochemical anomalies are of a low order.
This phenological study tests two hypotheses: 1) Mass-flowering of an individual shrub serves to attract a large number and high species richness of "opportunistic" pollinators; and 2) Mass-flowering induces long periods of pollinator constancy to one individual which results in low inter-plant movement of pollen. More than 22 species of insects and birds were observed to visit the flowers of the tropical shrub, Hybanthus prunifolius. However, high levels of effective pollination were restricted to the social bee, Melipona interrupta. This species showed highly density-dependent visitation responses at two levels: the individual mass-flowering plant and the highly synchronized population of plants. An individual was constant to one shrub for a short time period and visited only 5% of available flowers per visit. But the large number of visits per day (120) resulted in a high fruit set and ovule set. The level of cross-pollination was estimated to be as low as 10%. Pollen flow was commonly restricted to nearby neighbors (mean distance = 2.6 m). Gene flow was further restricted by a low distance of dispersal of seeds (mean distance = 1.9 m). This mass-flowering shrub, therefore, does not experience a high level of gene flow. The study also illustrates that levels of cross-pollination and fruit set are not determined solely by the phenological pattern of the individual plant. Pollination in this mass-flowering shrub is further influenced by its compatibility system, and the temporal and spatial densities of the population.
This study compares reproductive success of individual plants flowering and fruiting in an out of synchrony with the population. I test the hypotheses that reproductive synchrony enhances a plant's ability to: (1) attract pollinators, and (2) avoid seed predators. The prediction is that an individual in synchrony with its population has higher fruit and ovule set after pollination and has more seeds at dispersal time than an individual out of synchrony. The test species is Hybanthus prunifolius (Schult.) Schulze (Violaceae), a shrub on Barro Colorado Island, Panama. It normally flowers in response to a heavy rain that interrupts a drought in the dry season. An individual produces most of its flowers on a single day. The flowers are self-compatible, but require animal vectors to effect any pollination. To test hypotheses (1) and (2) I used water sprinklers to induce individual plants to flower prior to the normal triggering rain, thereby creating a highly asynchronous population which flowered before the natural population. Peak flowering day for individuals in the experimental asynchronous population spanned 35 d; the natural population spanned 35 d; the natural population spanned 4 d. Measurements included pollination success (ovule and fruit set) due primarily to the social bee Melipona interrupta, occupation of fruits by microlepidopteran larvae (Cosmoptericidae) and dipteran larvae (Lonchaeidae, Silba sp.), and final reproductive output (number of mature fruits and seeds). Individuals in all size categories in the natural synchronous population matured a greater number of seeds than individuals in the asynchronous population. Mean number of mature seeds per individual was 658 in the synchronous population; it was 62 mature seeds per individual in the asynchronous population. The large difference in such output occurred primarily because individuals in the synchronous population had greater pollination success than individuals in the asynchronous population (86% vs. 58% fruit set; 78% vs. 40% ovule set). In contrast, fruit infestation by microlepidopteran larvae was greater among individuals in the asynchronous population than in the synchronous population (11% vs. 5%). The combined effects of pollinators and seed predators were thus additive and produced intense selection against temporally isolated individuals. Similarly low seed output was occasionally observed for the few nonexperimental plants that flowered in response to a light rain during the dry season. Such individuals had lower levels of pollination and mature fruit production than plants that flowered when all others in the entire forest were in flower. The effect of space was similar to that of time. During the natural synchronous flowering period, individuals in sites of low spatial attracted fewer pollinators and incurred more predation than individuals in sites with high density. An evolutionary interpretation of these results is that stabilizing by both pollinators and seed predators maintains the present low variance in the timing of flowering and fruiting within Hybanthus prunifolius populations. Such effects may have been caused in the past in forging the origin of reproductive synchrony in plant populations.
Viola egglestonii Brainerd is a perennial, stemless blue violet endemic to cedar glades of Alabama, Georgia, Kentucky and Tennessee. Field observations and laboratory and greenhouse studies on its ecological life cycle were carried out for 4 years. Germination occurs in spring, and seeds require a period of stratification to break dormancy. Growth of seedlings is very slow, and it takes several years for them to flower. The annual growth cycle of juvenile and adult plants commences in late winter or early spring and ends with the onset of cold weather in November. Plants lose some and occasionally all of their leaves during long dry periods in summer but produce new ones when the soil is remoistened. During at least the 1st 2 years after germination all of the leaves are unlobed, but in mature plants the earliest leaves of spring are unlobed, later leaves are lobed and those of late summer and autumn unlobed. In flowering plants, chasmogamous flowers are produced in spring, and cleistogamous flowers are produced from late spring to autumn with the peak occurring during late summer and autumn. A period of vernalization is necessary for the production of chasmogamous flowers. Low competitive ability is the probable reason for the restriction of V. egglestonii to cedar glades. Its ability to tolerate drought allows the species to persist in the xeric cedar glade habitat where competition from other species is minimal.
The Violaceae exhibit a range of structural variability in the secondary xylem Included in the family are genera whose wood is strikingly primitive along with others that show more advanced, but not highly evolved, features In spite of the variation encountered, however, it would seem that the anatomist is dealing here with a secondary xylem that conforms to or varies around a single pattern The anatomical variability that does exist is in line with Melchior's division of the subfamily Violoideae into two tribes A preliminary search for evidence which could be brought to bear on the taxonomic placement of the Sauvagesieae was unproductive. On the other hand, the inclusion of the genus Leonia in the Violaceae received strong anatomical support, as did its assignment to a subfamily which presumably diverged early from the ancestral stock
A phylogenetic study of the genus Viola used internal transcribed spacer (ITS) DNA sequences for 44 taxa representing many infrageneric groups in Viola plus outgroups Hybanthus concolor and Noisettia orchidiflora. Parsimony and maximum likelihood approaches place Latin American sections basal in Viola, supporting an Andean origin for the genus. Groups of sect. Chamaemelanium, mostly stemmed and yellow-flowered with x = 6 chromosomes, intermingle with groups of sect. Nomimium that are stemless and white- or blue-flowered with x = 12 or an aneuploid number. Neither section is monophyletic, and the assemblage forms a weak clade or grade, depending on the analysis. The remaining sect. Nomimium groups with primarily blue flowers and x = 10 and aneuploid or polyploid numbers form a clade including Hawaiian sect. Nosphinium, with pansies of sect. Melanium (typically stemmed with multicolored flowers and x = 5 to 17) at the base. Phylogenetic relationships from ITS data herald the need for drastic remodeling of Viola. Proposed changes include splitting sect. Chamaemelanium and some of sect. Nomimium into several sections, transferring the remainder of Nomimium to the segregate sect. Viola, and merging Hawaiian sect. Nosphinium with the amphi-Beringian V. langsdorffii complex under the Langsdorffianae in sect. Viola.
S ummary
The floral biology of Viola riviniana Rchb., V. reichenhachiana Jord. and V. hirta L. is described in detail. The flowers are very complicated morphologically and many changes in the floral organs occur during anthesis. Differences in the flowering periods of the three species were found but comparisons of the length of flower life, the pollen and nectar presentation and the receptivity of the stigmatic surfaces showed few differences between species. Movements of the pedicel and corolla directly affect the outline and colour patterns presented by the flower and these are probably of prime importance in the attraction of insect visitors to these species. All the movements of the floral organs and the changes which they undergo together suggest that anthesis has two distinct phases. The first is characterized by the retention of pollen within the androecium and the second is characterized by the gradual displacement of pollen from the anthers to the petals. Pollination during the flrst phase is effected only by a few insect species which operate the pollination mechanism precisely. By contrast, pollination during the second phase may be effected by a wide variety of insect visitors and is not, therefore, entirely dependent upon the activities of a small number of highly adapted species, as previously supposed. This may be of critial importance to the many species of Viola which are predominantly in‐breeders. In the absence of highly adapted pollinators (which is frequently the case), the second phase of anthesis may be the only opportunity for out‐breeding. The frequency of pollen exchange in the three species is, therefore, partially dependent upon the change in the mode of pollen presentation during anthesis.
A small shrub Hybanthus floribundus (Lindl.) F. Muell. Violaceae growing in Western Australia accumulates nickel and cobalt to a very high degree. Values of up to 23% nickel in leaf ash may represent the highest relative accumulation of a metal on record. The high accumulation of nickel poses interesting problems in plant physiology and plant biochemistry.
Malpighiales are one of the least resolved of the major angiosperm orders; more comparative data are needed to elucidate deep relationships and character evolution within the order. This article reevaluates pollen and tapetal characters, with a focus on one major subclade, the parietal clade. Pollen structure and, where possible, development are examined in representatives of the parietal clade from Passifloraceae (Passiflora, Turnera), Salicaceae (Populus, Salix), and Violaceae (Viola), and in Euphorbia (Euphorbiaceae), Hypericum (Hypericaceae), and Linum and Reinwardtia (Linaceae) from other Malpighiales. Pollen and tapetal characters in the parietal clade and selected outgroups are tabulated, using both original observations and an extensive literature search. Optimization of pollen and tapetal characters onto a recent molecular phylogeny indicates that lalongate endoapertures are a potential synapomorphy for the parietal clade. Passifloraceae (including the former Turneraceae) have some potential apomorphies: larger pollen size, greater diversity in endoaperture shape, and a plasmodial tapetum. The occurrence of a thick bilayered or channeled apertural intine may support a sister relationship between Passifloraceae and Violaceae, together with pollen with more than three colporate apertures. Very small pollen size indicates that Goupiaceae are potentially more closely related to the Lacistemataceae-Salicaceae clade than to Passifloraceae-Violaceae. Highly apomorphic, thin-walled, inaperturate pollen occurs in the wind-pollinated Populus. Outside the parietal clade, Malpighiales pollen is highly diverse, including large, intectate, baculate pollen in Linaceae with an exine composed of sporopollenin granules that could be an example of paedomorphosis, and unusual aperture structure in Euphorbia, with similarities to opercula. This pollen diversity may be a consequence of the considerable ecological diversity of Malpighiales and their rapid radiation in the mid-Cretaceous, and it indicates the need for further work on pollen and tapetal characters in this clade.
SUMMARY Three populations of the cleistogamous species Oxalis acetosella and one population of the cleistogamous species Viola hirta (during 2 years), were investigated to determine whether the fertilization success of chasmogamous flowers influences the number of per ramet produced chasmogamous seeds, cleistogamous flowers, cleistogamous seeds and the total number of released seed per ramet. In both species chasmogamous (CH) flowers are produced before the cleistogamous (CL) ones. Fertilization success influenced number of produced CH seeds per ramet. In both species, ramets with one or more unfertilized CH flowers produced significantly fewer CH seeds. The number of produced CL flowers per ramet varied due to site membership (O. acetosella) and ramet size, but also due to the fertilization success of CH flowers. In both species, ramets with some CH flowers left unfertilized, responded with an increased production of CL flowers and seeds. In none of the species did the fertilization success of CH flowers influence the total seed output per ramet. Consequently, the increased production of CL flowers compensated for any loss in fruit- and seed-set owing to unsuccessful fertilization of CH flowers.
Viola subsect.Boreali-Americanae, confined to North America including northern México, has long been considered one of the most taxonomically difficult temperate
groups of the angiosperms. Hybridization, followed in some localities by introgression, has made it difficult for systematists
to discern the “core” species by using only standard macromorphological characters. Analyses that employed scanning electron
microscopy (SEM) of seed coats and petal trichomes generated new characters. SEM of the surface of seeds of each of the orthospecies
revealed a suite of primary and secondary sculpture characters unique to each species that are correlated with a suite of
macromorphological characters. In a number of species, SEM of petal trichomes provided additional unique characters. SEM of
the surface of seed coats enabled, also, the identification of instances of hybridization by revealing blends of structures
of the primary and secondary sculpture typical of different orthospecies and instances of putative introgression by revealing
deviations in surface structures from those typical of orthospecies. A procedure based on iterative examinations of macromorphology
and micromorphology, which was developed in this research, enable the discernment of hybrids and putative introgressants.
Combining the micromorphological and macromorphological data with ecological and phytogeographical data enabled the delimitation
of sixteen orthospecies.
Nectar is the most common floral reward that plants produce to attract pollinators. To determine the effect of nectar production on hawkmoth behavior, pollen movement, and reproductive success in Mirabilis multiflora, I manipulated nectar volumes and observed the subsequent foraging behavior of the hawkmoth Hyles lineata and the resulting pollen movement patterns. Individual hawkmoths visited significantly more flowers on plants with more nectar. The increase in flower visits significantly increased pollen deposition on stigmas and pollen removal from anthers when nectar volume was raised to twice the highest level found in nature. As hawkmoths visited flowers consecutively on a plant, the proportion of self pollen deposited on stigmas increased significantly and rapidly. Based on simulated hawkmoth visits, seed set was significantly reduced for flowers later in a visit sequence. A simple model combining these results predicts that the form of selection on nectar production varies depending on pollinator abundance. Using a multiple regression analysis a nearly significant (P < 0.08) effect of stabilizing selection was detected during a single season as predicted by the model for the prevailing hawkmoth abundance. Although increased nectar production may indirectly affect plant fitness by reducing resources available for other plant functions, the direct effect of high nectar production on pollinator behavior and self pollination may generally limit floral nectar production.
Nickel and Zn were determined in 57 taxa of western North American genera containing serpentine-tolerant species. The studies resulted in the identification of 3 varieties of Thlaspi montanum (var. montanum, var. siskiyouense, and var. californicum) which are hyperaccumulators (>1000 mu g/g dry mass) of Ni. These three taxa together with the previously reported Streptanthus polygaloides are the only hyperaccumulators of Ni so far reported for continental America. Significantly higher than normal Ni values (up to 664 mu g/g) were recorded for the serpentinophyte Viola cuneata. Elevated Zn levels (>1000 mu g/g dry mass) were also recorded in 4 of the Thlaspi taxa and confirms the tendency of many species of this genus to accumulate Zn. -from Authors Thlaspi montanum Streptanthus polygaloides Viola cuneata hyperaccumulators
Herbarium specimens (89) of Rinorea bengalensis collected throughout Southeast Asia, were analysed for their nickel content. Concentrations of up to 17,500 μg/g (dry weight) place this species in the hyperaccumulator (> 1000 μg/g) class. Plants growing over ultrabasic substrates invariably contained over 3000 μg/g Ni. Most major ultrabasic regions in the area covered by this plant's distribution were identified from the nickel content of the herbarium specimens and one previously unrecorded ultrabasic area in West Irian (Indonesia) was pinpointed.
Volatile components of violet leaves were extracted with 1,1,2-trichloro-1,2,2-trifluoroethane as well as hexane and analysed using GC, GC-MS and GC-FTIR. Quantitatively, the yields of leave solids varied greatly according to the experimental parameters. Qualitatively, the chemical composition differs with respect to the solvent used. More than 100 compounds were separated, of which 23 compounds have been identified, representing 95% of the total; 1-dodecanol, pentadeca-5,10-dien-1-ol, pentadec-5-en-1-ol, 1-octadecene, 1-eicosene and octadeca-9,12-dienoic acid are reported as violet leaf volatiles for the first time.
Morphological, cytological, and phytochemical data were incorporated into numerical and statistical analyses to produce a revision of Viola subsection Nuttallianae. A basic chromosome number of x = 6 was confirmed for this polyploid complex, which includes five species: V. vallicola, 2n = 12; V. tomentosa, 2n = 12; V. nuttallii, 2n = 24; V. praemorsa, 2n = 36 and 48; and V. bakeri, 2n = 48. Departures from recent authors include the recognition of two varieties in V. vallicola, vallicola and major (Hook.) Fabijan, based on flavonoid chemistry and distribution. Viola praemorsa is envisaged as embracing a wide range of morphological and chemical diversity, the extremes of which are recognized as the subspecies praemorsa, flavovirens (Pollard) Fabijan, and linguaefolia. In the absence of significant morphological or distributional differences between the V. linguaefolia and V. praemorsa subspecies major (sensu Baker and Clausen) and oregona, these three previously recognized taxa are included in subspecies linguaefolia. Based on cytological, morphological, and flavonoid data presented here, possible phylogenetic relationships are discussed.
This study has confirmed the occurrence of diploid and tetraploid races in Viola adunca J. E. Smith, in both of which sexual reproduction is normal. Also found to exist is a triploid which is sterile. The tetraploid is distributed widely in western Canada and the two races appear to be virtually allopatric. Differences have been found which permit separation of the races on morphological grounds. Taxonomic recognition of the two chromosome races is recommended but is not included here because necessary information on the type specimen is not available at the present time.
The pattern of fatty acid esters of violaxanthin and the minor xanthophylls in the petals of Viola tricolor (yellow varieties) is unusually complex. This is due to the fact that β-hydroxy acids (12:0, 14:0, 16:0) take part in the esterification in addition to the usual acids (12:0, 14:0, 16:0, 18:0).
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The distribution of pollen upon the insect‐visitors to three species of Viola is described and correlated with their feeding and cleaning behaviour. Visitors adopt one of two basic positions while feeding. In the prone position the insect alights on the anterior petal and probes for nectar so that its dorsal surfaces contact the floral genitalia. The supine position may be adopted after alighting on the anterior petal when the insect rotates so that it is virtually standing on its head. While probing for nectar from this position it is the ventral surfaces which contact the floral genitalia. Bumblebees adopt either feeding position; many large solitary bee species almost invariably adopt the supine one while large hoverflies always feed from the prone position. The behaviour of short‐tongued visitors tends to be highly individual with respect to contact with the floral genitalia and many body surfaces may be involved.
The varying activities of insect‐visitors while feeding result in the deposition of pollen at different locations on the integument. Consequently insect‐borne pollen is presented to the stigma in various ways and there is a spectrum of pollination effects: medium and long‐tongued nectar‐seeking insects tend to be systematic cross‐pollinators while short‐tongued or pollengathering species tend to be chance cross‐ or self‐pollinators.
The cleaning behaviour of insect‐visitors strongly influences pollination as it removes much integumental pollen. Two requirements of the pollen deposition mechanism are postulated: that pollen should be placed (a) in a position not occupied by foreign pollen and (b) in a position irregularly or inefficiently cleaned. There were no positions which were free of foreign pollen throughout the visitor‐species. On the other hand, violet pollen was found to be concentrated at locations inaccessible to the cleaning mechanism.
Systematic cross‐pollination results from the visits of a variety of insects with proboscides over 5 mm long including bumblebees, honeybees, solitary bees, hoverflies and beeflies, therefore, the violet flower is not simply a ‘bee flower’ as previously supposed. The widespread practice of generalizing on the role of insect‐visitors in pollination is questioned and the error in labelling flowers according to the taxonomic position of their pollinators is pointed out; the greater relevance of the morphological and behavioural characteristics of the insect‐visitors is emphasized.
Differences in the floral genitalia of these Viola spp. may reflect a shift from allogamy to facultative autogamy which, in turn, may be a response to a paucity of pollinators at certain seasons. However, the diverse range of pollinators may maintain some out‐crossing by the least efficient but more abundant short‐tongued pollinators.
The diversity of pollinators, therefore, provides a mechanism whereby a sexual system can simultaneously produce variation and invariance. The evolutionary versatility of a mating system incorporating this mechanism may have been partially responsible for the success of the genus Viola throughout the temperate regions of the world.