Number Of Stamens Research Articles

Up- and Down-regulated Expression of OsCPK25/26 Results in Increased Number of Stamens in Rice

Calcium-dependent protein kinases play important roles in the regulation of plant growth and development. Rice genome contains 31 CDPK genes, and the biological functions of most of these CDPK genes remain unclear. To elucidate the biological function of OsCPK25/26, we first analyzed the expression profiles for OsCPK25/26. Transcripts of OsCPK25/26 were observed in the panicles, hulls, and stamens, with significantly higher expression in stamens. Plasmid constructs of either overexpression of OsCPK25 or RNAi knockdown of OsCPK25/26 were created and introduced into the Zhonghua11 (Oryza sativa L. ssp. japonica) rice variety, and single-copy homozygous lines of the resultant transgenic plants were characterized. The expression levels of OsCPK25/26 in panicles were increased 11–15-fold in the overexpressing plants and decreased 1.5–1.7-fold in the plants expressing RNAi against OsCPK25/26 compared with that in the control plants. The numbers of stamens in some florets increased with varying degrees, ranging from six to 13 stamens in both the overexpressing and RNAi plants. Compared with the control plants, the proportion of florets with increased stamen numbers in T2 generation was 30 % in the overexpressing plants and 36 % in RNAi plants and that in T3 generation was 50 and 51 %, respectively. Our results suggest that OsCPK25/26 are involved in the regulation of stamen development, and changes (increases or decreases) of OsCPK25/26 expression levels result in an increased number of stamens. Thus, the optimal expression levels of OsCPK25/26 are a key regulating factor in maintaining normal stamen numbers in rice.

Cardamine hirsuta: a versatile genetic system for comparative studies

A major goal in biology is to identify the genetic basis for phenotypic diversity. This goal underpins research in areas as diverse as evolutionary biology, plant breeding and human genetics. A limitation for this research is no longer the availability of sequence information but the development of functional genetic tools to understand the link between changes in sequence and phenotype. Here we describe Cardamine hirsuta, a close relative of the reference plant Arabidopsis thaliana, as an experimental system in which genetic and transgenic approaches can be deployed effectively for comparative studies. We present high-resolution genetic and cytogenetic maps for C.hirsuta and show that the genome structure of C.hirsuta closely resembles the eight chromosomes of the ancestral crucifer karyotype and provides a good reference point for comparative genome studies across the Brassicaceae. We compared morphological and physiological traits between C.hirsuta and A.thaliana and analysed natural variation in stamen number in which lateral stamen loss is a species characteristic of C.hirsuta. We constructed a set of recombinant inbred lines and detected eight quantitative trait loci that can explain stamen number variation in this population. We found clear phylogeographic structure to the genetic variation in C.hirsuta, thus providing a context within which to address questions about evolutionary changes that link genotype with phenotype and the environment.

A Cucumber DELLA Homolog CsGAIP May Inhibit Staminate Development through Transcriptional Repression of B Class Floral Homeotic Genes

In hermaphroditic Arabidopsis, the phytohormone gibberellin (GA) stimulates stamen development by opposing the DELLA repression of B and C classes of floral homeotic genes. GA can promote male flower formation in cucumber (Cucumis sativus L.), a typical monoecious vegetable with unisexual flowers, and the molecular mechanism remains unknown. Here we characterized a DELLA homolog CsGAIP in cucumber, and we found that CsGAIP is highly expressed in stem and male flower buds. In situ hybridization showed that CsGAIP is greatly enriched in the stamen primordia, especially during the hermaphrodite stage of flower development. Further, CsGAIP protein is located in nucleus. CsGAIP can partially rescue the plant height, stamen development and fertility phenotypes of Arabidopsis rga-24/gai-t6 mutant, and ectopic expression of CsGAIP in wide-type Arabidopsis results in reduced number of stamens and decreased transcription of B class floral homeotic genes APETALA3 (AP3) and PISTILLATA (PI). Our data suggest that monoecious CsGAIP may inhibit staminate development through transcriptional repression of B class floral homeotic genes in Arabidopsis.

Evolution of stamen number in Ptychospermatinae (Arecaceae): Insights from a new molecular phylogeny of the subtribe

The palm subtribe Ptychospermatinae (Arecaceae: Arecoideae) is naturally distributed in the South West Pacific area and contains 12 genera and around 60 species, including numerous popular ornamentals. Like many palms, Ptychospermatinae flowers are small, trimerous, unisexual and always grouped into inflorescences of various sizes. However they exhibit a wide diversity in stamen number (a few to several dozen or even hundreds) that is poorly understood from an evolutionary point of view. Although advances have been made in elucidating phylogenetic relationships within Ptychospermatinae, some relationships among and within genera still remain to be clarified. Here we used a combination of five nuclear markers (nrITS2, the conserved nuclear intron BRSC10 and three low copy genes, PRK, RPB2 and AGAMOUS) and three chloroplast markers (matK, ndhA and rps15-ycf1) to propose a new phylogenetic hypothesis for the subtribe. The combination of all these markers improved the resolution and robustness of phylogenetic relationships within the subtribe, allowing us to identify four major clades. This phylogenetic framework was used to examine the evolution of stamen number in the clade. The optimization of stamen number on the phylogeny highlighted the high level of interspecific variability, showing that the character is highly labile and raising questions about the evolutionary and functional significance of this lability.

Nymphaea rubra Roxb. ex Andrews in Sri Lankan Fresh Waters

Native water lilies are wide spread in aquatic ecosystems in Sri Lanka and the RevisedHandbook to the Flora of Ceylon has recognized only two native water-lilies, Nymphaeanouchali Burm. f. and N. pubescens Willd. However, another night blooming Nymphaeaspecies with red flowers that is not either taxonomically described or recognized in the Floraduring the revision occurs in many parts of the country. A detailed taxonomic investigationwas carried out with field collected samples of all Nymphaea species occurring in local waterbodies. Forty eight morphological characters were studied in detail and coded into a datamatrix. Data were analysed using PAST software version 2.17.The multivariate analysis separated this group of Nymphaea from the other native Nymphaeaspecies as a separate phenetic group. Larger leaves (25-48 cm) with reddish purple abaxialand green adaxial surfaces, red petals and a larger number of stamens (62-103), and creamcolour stigmatic head are important characters that separates the group from its closeresemblance, N. pubescens. Comparing the morphological features of the individuals in thisphenetic group with taxonomic descriptions of N. rubra, confirmed their identity as N. rubra.A complete morphological description and an identification key to separate the differentNymphaea species occurring in Sri Lanka were constructed.

The evolution of sex ratio differences and inflorescence architectures in Begonia (Begoniaceae)

A major benefit conferred by monoecy is the ability to alter floral sex ratio in response to selection. In monoecious species that produce flowers of a given sex at set positions on the inflorescence, floral sex ratio may be related to inflorescence architecture. We studied the loci underlying differences in inflorescence architecture between two monoecious Begonia species and related this to floral sex ratios. We performed trait comparisons and quantitative trait locus (QTL) mapping in a segregating backcross population between Central American Begonia plebeja and B. conchifolia. We focused on traits related to inflorescence architecture, sex ratios, and other reproductive traits. The inflorescence branching pattern of B. conchifolia was more asymmetric than B. plebeja, which in turn affects the floral sex ratio. Colocalizing QTLs of moderate effect influenced both the number of male flowers and the fate decisions of axillary meristems, demonstrating the close link between inflorescence architecture and sex ratio. Additional QTLs were found for stamen number (30% variance explained, VE) and pollen sterility (12.3% VE). One way in which Begonia species develop different floral sex ratios is through modifications of their inflorescence architecture. The potential pleiotropic action of QTL on inflorescence branching and floral sex ratios may have major implications for trait evolution and responses to selection. The presence of a single QTL of large effect on stamen number may allow rapid divergence for this key floral trait. We propose candidate loci for stamen number and inflorescence branching for future characterization.

Early floral development of Pentaphylacaceae (Ericales) and its systematic implications

Early floral development of four species from the genera Anneslea, Cleyera, Eurya, and Ternstroemia of Pentaphylacaceae, was studied comparatively using scanning electron microscopy. Together with earlier studies in Euryodendron and Adinandra, 6 out of 12 genera of Pentaphylacaceae have now been studied for their floral development. The usually pentamerous flowers of these taxa share a number of developmental features: the perianth organs appear in a clockwise or anticlockwise spiral sequence on the floral apex with relatively long plastochrons between successive organs, resulting in conspicuous size differences among perianth organs during early developmental stages. The early development of the usually polystemonous androecium is characterized by an indistinct ring-primordium and a mostly concave floral apex; individual stamens appear subsequently on this ring-primordium. However, further development of the androecium differs conspicuously among taxa and we describe three main developmental patterns for the family including features such as centripetal stamen whorls and stamens fascicles. Unusual features of floral development and organization of Pentaphylacaceae include: (1) a pronounced spiral sequence of organ appearance during early floral development in perianth and androecium; (2) the occurrence of paired organs in the corolla and the androecium of some species; (3) sepals and petals that are positioned opposite from each other in the genera Anneslea and Ternstroemia; and (4) a concave floral apex at the beginning of androecium development. From a systematic point of view our results clearly support a close relationship between Anneslea and Ternstroemia and also suggest a closer relationship among Adinandra, Cleyera, and Euryodendron on the one hand and between Eurya and Visnea on the other. Further, our developmental study stresses the differences between Pentaphylacaceae and Theaceae, which earlier where thought to form a natural group of plants. While high stamen numbers are achieved via centripetal pattern of stamen formation in the former family, stamens are formed centrifugally in the latter.

O gênero Mimosa L. (Leguminosae: Mimosoideae) na APA Serra Branca/Raso da Catarina, Bahia, Brasil

This work consists of a floristic survey of the genus Mimosa L. in APA Serra Branca/Raso da Catarina, located in Jeremoabo, Bahia, Brazil. We analyzed specimens collected from June/2010 to October/2011 and collections deposited in the ALCB, HRB, HUEFS, and MBM herbaria. We registered 11 species distributed in two sections: Mimosa sect. Batocaulon DC. (Mimosa acutistipula (Mart.) Benth. var.acutistipula, M. adenophylla var. mitis Barneby, M. arenosa (Willd.) Poir. var. arenosa, M. caesalpiniifolia Benth., M. lewisii Barneby, M. misera Benth., M. piscatorum Barneby, M. quadrivalvis var. leptocarpa (DC.) Barneby, and M. tenuiflora (Willd.) Poir.) and Mimosa sect. Mimosa (M. pudica var. tetrandra (Humb. & Bonpl. ex Willd.) DC. And M. sensitive L. var. sensitiva). The main characters used for delimitation of the species were inflorescence morphology, number of pinnae, leaflets, perianth elements and stamens, as well as aspects from the fruit. The species occurs mainly open areas and more degraded along trails on sandy soils. Keys for identification of species, descriptions, illustrations and comments about geographic distribution and flowering and fruiting periods of the species are presented.

Flower structure and sex expression of leaky dioecy in Eurya obtusifolia

The genus Eurya is described as strictly dioecious, but rare leaky plants have been found in some species, causing much confusion about the sex expression of the genus. Through field investigations from 2009 to 2011, morphologically hermaphroditic flowers in Eurya obtusifolia were discovered. In order to understand the sex expression of these plants, their stamens, pistils and ovules were carefully observed. Staining methods were used to assess the functional gender. The flowers of the leaky plants can be classified into six types: pistillate, staminate, cryptic pistillate, cryptic staminate, hermaphrodite and infertile. Leaky plants usually exhibit a combination of different kinds of flowers, making them either gynoecious, androecious, gynomonoecious or monoecious. Some individuals have infertile flowers. Bagging experiments verified the bisexual function of E. obtusifolia plants, some of which possess the ability to self‐pollinate. The flower morphology of leaky plants varied more than that of dioecious ones, and the number of ovules were significantly negatively correlated with the number of stamens. These plants show lower fitness than normal dioecious plants. This may owe to allocation tradeoffs or sexual genome conflicts. As leaky dioecy is rarely reported in this genus, E. obtusifolia is an important species to study in order to better understand the ecological adaptations and evolutionary pathways that lead to dioecy in Eurya. Our findings provide some evidence that dioecy of Eurya evolved from hermaphroditism, but further studies are still needed.

Reevaluation of the perianth and androecium in Caryophyllales: implications for flower evolution

The Caryophyllales have the highest diversity in androecial patterns among flowering plants with stamen numbers ranging from 1 up to 4,000. Thanks to the recent progress in reconstructing the phylogeny of core Caryophyllales, questions of floral evolution, such as the origin and diversification of the androecium, can be readdressed. Caryophyllales are unique among core eudicots in sharing an androecial ring meristem or platform with centrifugal development of stamens and petals. Stamens are basically arranged in two whorls and evolution within the clade depends on the shift of either the antesepalous or the alternisepalous whorls to an upper position on the ring meristem and the reduction of the other. Four main developmental phenomena are responsible for the high diversity in androecial patterns: (1) the sterilisation of the outermost stamens through a division of common primordia; (2) the secondary addition of stamens by a centrifugal initiation of supernumerary stamens superimposed on a lower stamen number; (3) the pairwise displacement of alternisepalous stamens to the middle of the outer sepals and their potential fusion, or as part of a pluristaminate androecium; (4) the inversed sequence, reduction and loss of antesepalous stamens. Shifts in stamen numbers depend on pressures of the calyx and carpels and changes in the number of the latter. These patterns are expressed differently in the three main evolutionary lines of core Caryophyllales and are systematically relevant: (1) A basal grade of Caryophyllales, culminating with Caryophyllaceae, Amaranthaceae, Stegnosperma and Limeum, has the antesepalous stamens initiated in upper position on the ring meristem, and alternisepalous stamens are preferentially reduced. Among the antesepalous whorl there is a progressive loss of stamens following a sequence inversed to sepal initiation. Petaloid staminodes are formed by the radial division of outer stamens. (2) The raphide-clade and Molluginaceae are characterized by alternisepalous stamens in upper position on the ring meristem, with a trend to secondary stamen multiplication, and loss of antesepalous stamens. (3) The Portulacineae share the pattern of the raphide clade, but some taxa show shifts to an upper position on the ring meristem of either antesepalous or alternisepalous stamens, linked with secondary multiplications and reduction of either whorl. Different floral characters are plotted on a recent cladogram of Caryophyllales. The data show a consistent correlation between shifting carpel and stamen numbers independent of perianth evolution. Comparative data suggest that the basic androecium of Caryophyllales consists of two whorls of five stamens, linked with an absence of petals, and the evolution of the androecium is a combination of reductions and secondary multiplications of stamens with a highly predictive systematic value.

Phylogenetic Systematics of the Mesa Mints: <I>Pogogyne</I> (Lamiaceae)

Abstract Pogogyne (Lamiaceae) is a small genus of annual plants, occurring almost entirely in vernal pool habitats. To infer the phylogenetic relationships of this group, DNA sequence data from the trnQ-rps16 chloroplast spacer and both ETS and ITS nuclear regions were obtained from all seven extant species and several outgroups and analyzed using both parsimony and Bayesian phylogeny reconstruction methods. Ancestral state reconstructions were performed for morphological characters that have been used to separate groups within Pogogyne. This study indicates that subgenus Hedeomoides is monophyletic with good support and can be diagnosed by two apomorphies: a reduction in stamen number and a reduced corolla size. Subgenus Pogogyne is paraphyletic, but with poor support. Several clades within the genus Pogogyne have discrete biogeographic distributions. The Pogogyne genus clade has a relatively long stem lineage, but its crown clade has quite short branches. Our estimate for the mean divergence time of the...

Pollen production and depositional behaviour of teak (Tectona grandis Linn. F.) and sal (Shorea robusta Gaertn. F.) in tropical deciduous forests of Madhya Pradesh, India: An overview

Teak (Tectona grandis Linn. F.) of the family Verbenaceae and Sal (Shorea robusta Gaertn. F.) of Dipterocarpaceae, are dominating as well as important constituents of tropical deciduous forests of India and Madhya Pradesh, constituting about 24–26% of the total forest flora of the country. These two taxa are high pollen producers, but their pollen grains are retrieved in lesser frequencies in the sediments (surface samples, moss cushions/polsters, samples of sediment profiles/cores). This peculiar behaviour in the representation of their pollen grains could be attributed to poor pollen preservation in the sediments as well as low dispersal efficiency. However, microbial as well as chemical degradation of their pollen in the sediments cannot be ruled out. The number of stamens, flowers, inflorescences on a plant, anther size, pollen grain size, and types and nature of pollination are also related with the abundance of pollen. Genotypes in association with the variations in environmental factors could also govern the pollen production of a particular taxon/variety. In addition to knowing the pollen productivity of the taxa, assessing the representation of the taxa in extant vegetation is helpful in establishing the modern pollen/vegetation relationships which serve as modern analogues for the appropriate explanation of fossil pollen diagrams.

Isolation and functional analysis of the ClM8-FRUITFULL-like MADS-box gene from Chrysanthemum lavandulifolium

AP1/FUL-like genes encode class-specific MADS box transcription factors in angiosperms and play important roles in the plant floral transition and floral organ identity. Chrysanthemum lavandulifolium (Fisch. ex Trautv.) Makino is one of the original species of Chrysanthemum. Understanding the function of AP1/FUL-like genes in C. lavandulifolium provide molecular-level insight into the flowering mechanism of Chrysanthemum. Here, an AP1/FUL-like gene was isolated from C. lavandulifolium. Sequence and phylogenetic analyses indicated that this gene, ClM8, belongs to the euFUL clade of the AP1/FUL-like genes. We observed different expression levels of ClM8 in C. lavandulifolium roots, stems, fruits and leaves and high expression in the flowers. A subcellular localisation assay showed that ClM8 is localised to the nucleus in vivo. The over-expression of ClM8 in Arabidopsis resulted in altered flowering time and inflorescence structure. These aberrant, transgenic Arabidopsis plants showed early flowering following the production of four to six small rosette leaves, lateral flowers and a composite terminal flower. The terminal flower consisted of two or four pistils surrounded by an abnormal number of sepals, petals and stamens. In addition, the morphology of the style of 35S::ClM8 plants silique differed from wild type, appearing thinner and longer. Further investigation suggested that the expression levels of FLOWERING LOCUS T (FT), LEAFY (LFY) and APETALA1 (AP1) were apparently increased in ClM8-transgenic Arabidopsis. Thus, we speculate that ClM8 promoted flowering in Arabidopsis due to the upregulation of FT. Taken together, our results suggest that ClM8 is involved in flowering induction and floral development that might also play a role in the development of fruits and leaves.

Flower development in Abrus precatorius (Leguminosae: Papilionoideae: Abreae) and a review of androecial characters in Papilionoideae

The jequirity bean (Abrus precatorius) is well known because of its shiny black and red coloured seeds and because of the poison (abrin) it contains. The genus Abrus is placed in a monogeneric tribe Abreae which is placed in a relatively isolated systematic position at the base of Millettieae. To contribute to a better understanding of this taxon, a detailed ontogenetic and morphologic analysis of its flowers is presented. Floral primordia are subtended by an abaxial bract and preceded by two lateral bracteoles which are formed in short succession. Sepal formation is unidirectional starting abaxially. All petals are formed simultaneously. The carpel is formed concomitantly with the outer (antesepalous) stamen whorl, which arises unidirectionally, starting in an abaxial position. In the inner, antepetalous stamen whorl two abaxial stamens are formed first, followed by two lateral stamen primordia. The adaxial, antepetalous position remains organ free (i.e. this stamen is lost). Later in development the nine stamen filaments fuse to form an adaxially open sheath. The filament bases of the two adaxial outer-whorl stamens grow inwards, possibly to provide stability and to compensate for the lost stamen. In the mature flower a basal outgrowth can be found in the position of the lost stamen. However this is more likely to be an outgrowth of the filament sheath rather than a remnant of the lost stamen. These ontogenetic patterns match in parts those found in other Millettieae (unidirectional formation of sepals and stamens, simultaneous petal formation). In contrast, the complete loss of a stamen is rather unusual and supports the isolated position of Abreae and probably justifies (among other characters) its tribal status. A review of androecial characters shows that androecial merosity is on the one hand extremely variable among Leguminosae, varying from a single stamen per flower to more than 500. On the other hand it is noteworthy that the number of stamens becomes stabilised in more derived Papilionoideae such as the large non-protein-amino-acid-accumulating clade (NPAAA clade). This indicates that the androecium has played an important role in the success of a major part of Leguminosae.

Características florais e carpométricas e germinação in vitro de grãos de pólen de cultivares de amoreira‑preta

O objetivo deste trabalho foi avaliar as características florais e carpométricas, a viabilidade dos grãos de pólen e a capacidade germinativa de sementes de cultivares de amoreira‑preta. Foram avaliadas as cultivares Brazos, Caingangue, Cherokee, Choctaw, Comanche, Guarani, BRS Tupy e Ébano. Utilizou-se um delineamento experimental inteiramente casualizado com as oito cultivares e dez repetições. Foram feitas avaliações quanto a: número de estames, carpelos, pétalas e sépalas; composição do meio de cultura; número de grãos de pólen por antera e por flor; taxa de germinação de grãos de pólen; percentagem de frutificação; massa de matéria fresca, dimensões e número de sementes dos frutos; massa e dimensões dos drupetes; e percentagem de emergência de plântulas. O meio de cultura estabelecido para as cultivares de amoreira‑preta foi acrescido de 90 g L‑1 de sacarose e 400 mg L‑1 de ácido bórico, com pH aferido para 6,5 e meio solidificado com 8 g L‑1 de ágar. 'Caingangue', 'Ébano' e 'BRS Tupy' apresentaram baixa germinação de grãos de pólen. 'Ébano' apresentou frutos arredondados e com poucos drupetes. 'Choctaw' e 'Comanche' apresentaram baixa percentagem de emergência de plântulas. 'Brazos' destacou-se na maioria das características avaliadas e é considerada como boa progenitora para programas de melhoramento genético.

Duplicated STM-like KNOX I genes act in floral meristem activity in Eschscholzia californica (Papaveraceae)

In angiosperms, the shoot apical meristem is at the origin of leaves and stems and is eventually transformed into the floral meristem. Class I knotted-like homeobox (KNOX I) genes are known as crucial regulators of shoot meristem formation and maintenance. KNOX I genes maintain the undifferentiated state of the apical meristem and are locally downregulated upon leaf initiation. In Arabidopsis, KNOX I genes, especially SHOOTMERISTEMLESS (STM), have been shown to regulate flower development and the formation of carpels. We investigated the role of STM-like genes in the reproductive development of Eschscholzia californica, to learn more about the evolution of KNOX I gene function in basal eudicots. We identified two orthologs of STM in Eschscholzia, EcSTM1 and EcSTM2, which are predominantly expressed in floral tissues. In contrast, a KNAT1/BP-like and a KNAT2/6-like KNOX I gene are mainly expressed in vegetative organs. Virus-induced gene silencing (VIGS) was used to knockdown gene expression, revealing that both EcSTM genes are required for the formation of reproductive organs. Silencing of EcSTM1 resulted in the loss of the gynoecium and a reduced number of stamens. EcSTM2-VIGS flowers had reduced and defective gynoecia and a stronger reduction in the number of stamen than observed in EcSTM1-VIGS. Co-silencing of both genes led to more pronounced phenotypes. In addition, silencing of EcSTM2 alone or together with EcSTM1 resulted in altered patterns of internodal elongation and sometimes in other floral defects. Our data suggest that some aspects of STM function present in Arabidopsis evolved already before the basal eudicots diverged from core eudicots.

Reseda minoica(Resedaceae), a New Species from the Eastern Mediterranean Region

Reseda minoica Martín-Bravo & Jim. Mejías (Resedaceae), a new species from the eastern Mediterranean region, is described and illustrated. It is distributed in Crete (Gavdos Island), Cyprus and S Anatolia (Mersin), where it grows mostly on basic, occasionally schistose, substrates near the coast. It is included in Reseda sect. Phyteuma, a taxonomically complex group mostly containing narrow endemics from the western or eastern Mediterranean region. Reseda minoica has been confused with R. odorata, R. orientalis and R. balansae in Crete, Cyprus and Turkey. It can be distinguished from those by the lower number of stamens, seed size, colour of petals and indumentum. An identification key to the eastern Mediterranean taxa of Reseda sect. Phyteuma is provided.

A New Species of <I>Kuhlmanniodendron</I> (Lindackerieae, Achariaceae) from Eastern Brazil and the Systematic Position of the Genus in Achariaceae

Kuhlmanniodendron macrocarpum Groppo, Favaretto & Fiaschi (Lindackerieae, Achariaceae), a second species of the genus, is here described and illustrated. This species is known from a small number of collections from the state of Bahia, eastern Brazil, and considered endangered given its restricted geographical distribution and the rapid deforestation of the Brazilian Atlantic Rain Forest. Kuhlmanniodendron macrocarpum can be readily distinguished from K. apterocarpum, the other species of the genus, by its larger fruits (5-8 + 4-6 cm vs. 3-4 + 2.5-3 cm), the leaf venation pattern, and the disposition and number of stamens in male flowers. In addition to morphological characters used to characterize the new species, phylogenetic analyses were carried out using an rbcL sequence from the new species together with other Malpighiales sequences deposited in GenBank. These analyses involved maximum parsimony and Bayesian inference. The results confirmed the close relationship of the new species with K. apterocarpum in a strongly supported clade. Kuhlmanniodendron appeared close to Camptostylus, Lindackeria, Xylotheca, and Caloncoba in a strongly supported clade (posterior probability = 0.99) that cor- responds with the tribe Lindackerieae of Achariaceae (Malpighiales). The arrangement of the stamens in the male flowers of the new species were investigated using transversal anatomical sections, revealing a combination of stamens with basally connate filaments externally arranged in a ring and internally arranged in sets of three (or two), the first report of this pattern of stamen arrangement in Achariaceae. Pollen of K. macrocarpum are 3-colporate and microreticulate, and typical of many eudicots. A picrosodic paper test was performed in herbarium dry leaves, and cyanogenic glycosides, a class of compounds usually found in Achariaceae, were detected. A detailed description and illustrations of this new species are provided, as well as comments on geographic distribution, phenology, generic relationships, and conservation status.

Tracking the development of the petaloid fertile stamen in Canna indica: insights into the origin of androecial petaloidy in the Zingiberales

Flowers of the order Zingiberales demonstrate a remarkable trend of reduction in the number of fertile stamens; from five or six fertile, filamentous stamens bearing two thecae each in Musaceae and Strelitziaceae to just a single petaloid stamen bearing a single theca in Cannaceae and Marantaceae. As one progresses from ancestral to derived floral forms, 5-6 fertile stamens are replaced by 4-5 petaloid staminodes. In Cannaceae and Costaceae, all members of the androecial whorls exhibit petaloidy, including the fertile stamen. In Costaceae, a single fertile stamen develops two thecae embedded on a broad petaloid appendage, while in Cannaceae the single fertile stamen is further reduced to a single theca with a prominent, expanded petaloid appendage. Whether petaloidy of the fertile stamen is a synapomorphy of the entire ginger clade (including Cannaceae, Costaceae, Zingiberaceae and Marantaceae), or the result of independent convergent evolution in Cannaceae, Costaceae, and some Zingiberaceae, is unclear. We combine a developmental series of the formation of the petaloid fertile stamen in Canna indica with data on the expression of B- and C-class floral organ identity genes to elucidate the organogenetic identity of the petaloid stamen and staminodes. Our data indicate that the single fertile theca in C. indica and its petaloid appendage are derived from one-half of the primordium of a single stamen, with no contribution from the remaining part of the stamen (i.e. the second theca primordium) which aborts early in development. The petaloid appendage expands later, and develops from the position of the filament/connective of the developing theca. Floral identity gene expression shows that petal identity genes (i.e. B-class genes) are expressed in all floral organs studied while C-class gene AG-1 is expressed in an increasing gradient from sepals to gynoecium, and AG-2 is expressed in all floral organs except the petals. The canonical model for molecular specification of floral organ identity is not sufficient to explain petaloidy in the androecial whorl in Canna sp. Further studies understanding the regulation of gene networks are required.

Multivariate analysis of morphological and anatomical characters ofCalophyllum(Calophyllaceae) in South America

Calophyllum (Calophyllaceae), previously placed in Clusiaceae, is easily recognizable by its opposite entire leaves with close parallel venation alternating with resin canals. However, distinction between species has been difficult, because of infraspecific variation in tepal and stamen number and resemblance among species that share similar habitats. Here, I report the results of multivariate analyses of morphological and anatomical characters for Calophyllum in South America, and provide a taxonomic treatment for the genus in South America, the first since that of Vesque in 1893. Thirteen preliminary morphogroups were identified. Thirty-two morphological characters of the leaf, flower and fruit from 401 specimens, and 17 anatomical leaf characters from 45 specimens were measured and analysed using principal component analyses (PCAs) and discriminant analyses (DAs). PCAs were used to find groups and DAs were used to validate those PCAs that were potential groups. Two main subgroups were identified in the general analysis. Subgroup M1 has terete stems and smaller leaves and flowers than subgroup M2, which, instead, has quadrangular stems. Only subgroup M2 showed distinctive clusters in regional and local analyses. Distinctive clusters and morphological and anatomical characters helped us to recognize four species in South America, including a new species, Calophyllum pubescens sp. nov.. In addition, a new species, Calophyllum mesoamericanum sp. nov., is described from Central America. © 2013 The Linnean Society of London,