The resurrection of Erigeron parryi (Asteraceae)

Erigeron parryi was described in 1890 from a single collection from southwest Montana. No additional collections were made during the following 90 years. Recent floristic treatments have synonomized E. parryi under E. ochroleucus. I used principal components and discriminant analyses of morphological characters to examine the relationship of E. parryi to its presumed closest relatives, E. ochroleucus, E. radicatus, and E. scribneri, in light of several populations discovered in the past 20 years. Erigeron parryi should be considered a distinct species. It can be readily distinguished from closely related species based on indument and caudex morphology. It is allopatric with E. ochroleucus and E. scribneri and ecologically separated from E. radicatus. Erigeron scribneri is intermediate between E. ochroleucus and E. radicatus and is probably best treated as a variety of one or the other of these species.     

Chemotaxonomic value of flavonoids in Chromolaena congesta (Asteraceae)

The phytochemical investigation on the aerial parts of Chromolaena congesta led to the isolation of nine flavonoids, known in the literature as genkwanin (1) kumatakenin (2) acacetin (3), kaempferol 3-methyl ether (4), apigenin (5), apigenin 5,7-dimethyl ether (6), apigenin 5-methyl ether (7), luteolin (8) and kaempferol (9). The chemical structures were established on the basis of spectral evidence. All the compounds were isolated from this species for the first time. The results from the present study provide further information about the flavonoids as taxonomic marker of the genus Chromolaena, and the chemotaxonomic significance of these compounds were also summarized.     

The internal cuticle of Cirsium horridulum (Asteraceae) leaves

Leaf internal cuticle has not previously been studied in detail, and yet its existence has profound implications for the path of water movement. The internal cuticle forms a uniform layer on the inner periclinal epidermal walls that border substomatal cavities. This cuticle is continuous with the external cuticle through the stomatal pores. The thickness of the internal cuticle on nonstomatal epidermal cells is approximately one-third that of the external cuticle on the same cells. On both the abaxial and adaxial sides of the leaf the internal cuticle forms irregularly shaped islands bordered by mesophyll cells. The size of the islands coincides with the epidermal area of the substomatal cavity. The internal cuticle remains intact and connected to the external cuticle after incubation in cellulytic enzymes. After treatment with sulfuric acid or chloroform, both cuticles remain intact. The autofluorescence of both cuticles is increased by staining with auramine O. These results indicate that large portions of the leaf epidermis are covered by both an internal and an external cuticle.     

A taxonomic revision of Centaurea section Acrocentron (Asteraceae) in Iran

The taxonomic status of Centaurea section Acrocentron in Iran is briefly reviewed. A critical study of 251 herbarium specimens, and an additional 37 accessions collected specifically for this research, led to the discovery of a new variety, Centaurea irritans var. longispinosa Montazerolghaem , and the revival of another, C. persica var. subinermis, a taxon previously treated as a synonym for about 25 years. A key to all Iranian species of Centaurea section Acrocentron is provided. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 99–106.     

Nine polymorphic microsatellite markers in Crepis sancta (Asteraceae)

We describe nine new variable di‐ and trinucleotide microsatellites in the plant Crepis sancta, as well as conditions for multiplexing and simultaneous genotyping sets of loci. Their variability was assessed in four populations. Four to 33 alleles were detected per locus; two to 23 alleles per population. Significant deviations from Hardy–Weinberg equilibrium could be attributed either to a mating system involving partial selfing or to null alleles. Genetic differentiation over all loci was significant among the four populations studied. These markers will constitute an efficient tool for investigating dispersal patterns in fragmented landscapes. Cross‐species amplification provided few loci variability in three other Crepis species (C. pulcra, C. foetida and C. rubra).     

Flavonoids of Pallenis spinosa (Asteraceae)

Pallenis spinosa was investigated for its flavonoid content. Two mono- and diglycosides of patuletin, a quercetin monoglycoside, two tricin monoglycosides, and four methoxylated flavonols were reported.     

Taxonomic significance of pollen types in the Guyana Highland-centred composite genera of Mutisioideae (Asteraceae)

The Guyana Highland-centred genera, or Stenopadus group, are a complex of species that belong to the tribes Mutisieae and Stifftieae of Asteraceae. The pollen morphologies of 29 species, from 12 of 13 genera of this complex, are described and illustrated using light and scanning electron microscopy. The exine sculpture and structure are highly significant. Four exine types, previously characterized, were distinguished: Gongylolepis , Wunderlichia , Mutisia , and Stenopadus . The characterization of the Stenopadus exine type is enlarged here. These exine types led to the recognition of four well-defined pollen types, whereas the spine length and exine thickness characterized six subtypes. Pollen types circumscribe genera or groups of genera, and some subtypes distinguish species. The pollen morphology within the complex is discussed in relation to the rest of Mutisioideae and other palynologically allied tribes of Cichorioideae. There is little correlation between pollen types and tribes; only the Stenopadus exine type is exclusive to the Stifftieae tribe. The remaining types are shared by the two tribes of the complex. Pollen morphology supports the hypothesis that this group of genera is close to the Gochnatia complex and the Cardueae tribe.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 327–340.     

Cleistogamous capitulum in Centaurea melitensis (Asteraceae): heterochronic origin

Cleistogamous capitula formed by Centaurea melitensis display a number of morphological and functional changes with respect to chasmogamous capitula that ensure self-fertilization. Because no studies have hitherto addressed the evolution of cleistogamy in Asteraceae, it was considered useful to ascertain whether these changes are attributable to one or more of the heterochronic processes reported in the literature. Bivariate allometric analyses were performed, and changes were represented graphically using Gould's clock models for size, shape, and age of several capitulum and floret structures. Results suggest that the partially paedomorphic appearance of cleistogamous with respect to chasmogamous capitula is attributable to three processes: (1) early onset of floral development (predisplacement), (2) decreased growth rate of the whorls studied (except gynoecium width) and (3) early offset time (progenesis). The latter appears to play the most significant role in the origin of the cleistogamous capitulum.     

The development of pistillate and perfect florets in Xeranthemum squarrosum (Asteraceae)

The formation of capitulum inflorescence with two different types of floret is an interesting issue in floral biology and evolution. Here we studied the inflorescence, floral ontogeny and development of the everlasting herb, Xeranthemum squarrosum, using epi‐illumination microscopy. The small vegetative apex enlarged and produced involucral bracts with helical phyllotaxy, which subtended floret primordia in the innermost whorl. Initiation of floret primordia was followed by an acropetal sequence, except for pistillate peripheral florets. The origin of receptacular bracts was unusual, as they derived from the floral primordia rather than the receptacular surface. The order of whorl initiation in both disc and pistillate flowers included corolla, androecium and finally calyx, together with the gynoecium. The inception of sepals and stamens occurred in unidirectional order starting from the abaxial side, whereas petals incepted unidirectionally from the adaxial or abaxial side. Substantial differences were observed in flower structure and the development between pistillate and perfect florets. Pistillate florets presented a zygomorphic floral primordium, tetramerous corolla and androecium and two sepal lobes. In these florets, two sepal lobes and four stamen primordia stopped growing, and the ovary developed neither an ovule nor a typical stigma. The results suggest that peripheral pistillate florets in X. squarrosum, which has a bilabiate corolla, could be considered as an intermediate state between ancestral bilabiate florets and the derived ray florets.     

Natural products from Tolpis barbata (L.) Gaertn. (Asteraceae,Cichorieae)

One sesquiterpene lactone – 9α-hydroxy-3-deoxyzaluzanin C, three benzopyrans: desmethoxyencecalin (6-acetyl-2,2-dimethylchromene), desacetylripariochromen B and 6-(1-hydroxyethyl)-2,2-dimethylchromene, one coumarin – scopoletin and two eugenol derivatives were isolated from the roots of Tolpis barbata (L.) Gaertn, hitherto unexamined species. In the extract from aerial parts of the plant, five known phenolic compounds, namely: esculin, esculetin, chlorogenic acid (5-CQA), luteolin 7-O-glucoside and 3,5-dicaffeoylquinic acid (3,5-DCQA) were identified as major constituents. Except for the two coumarins – scopoletin and esculetin, which were previously obtained from Tolpis webbii Sch.Bip. and T. proustii Pit., the isolated and identified compounds have not been previously reported as constituents of Tolpis spp. Though benzopyrans were found in numerous species of the Asteraceae, their occurrence in the tribe Cichorieae has not been demonstrated before.     

Phenolics from Tanacetum sinaicum (Fresen.) Delile ex Bremer & Humphries (Asteraceae)

The phytochemical investigation on Tanacetum sinaicum (Fresen.) Delile ex Bremer & Humphries led to the isolation of eight flavonoid aglycones (apigenin 1, acacetin 2, luteolin 3, chrysoeriol 4, cirsilineol 5, jaceidin 6, chrysosplenetin 7 and vitexicarpin; casticin 8), four flavonoid glycosides (apigenin 7-O-β-glucopyranoside 9, apigenin 7-O-β-glucuronide 10, luteolin 7-O-β-glucopyranoside 11 and luteolin 7-O-β-glucuronide 12) and three phenolics (4-hydroxy-3-methoxy benzoic acid 13, 3,4-dimethoxy benzoic acid 14 and 4-hydroxy acetophenone 15). Their structures were determined by chemical and spectroscopic analysis. Among them, compounds 1–3, 9, 11, 13 and 14 were reported for the first time from T. sinaicum. The chemotaxonomic significance of the isolated flavonoids was also summarized.     

6-Phosphogluconate Dehydrogenase (6PGD) Gene Duplication in Kalimeris (Asteraceae)

Abstract The genus Kalimeris with a diagnostic character of short or inconspicuous pappus consists of two sections, Asteromoea and Cordifolium. As a result of 6PGD isozyme analysis, sect, Asteromoea, including 2 × and poly-ploid taxa from 5 × to 8 ×, show similar cytosolic isozyme multiplicity and share a monomorphic locus. The data suggest that gene duplication of polyploid members was derived from a common ancestor. K. miqueliana, belonging to sect. Cordifolium. also possessed a gene duplication in 6PGD, though significant differences were detected in electrophoretic mobility between the sections. The occurrence of gene duplication in East Asian diploid Astereae leaves intact the validity of the allopolyploid-origin hypothesis of n= 9, which was rejected by Gottlieb (1981a) in American Astereae.     

Genotypic variation in agamospermous Erigeron compositus (Asteraceae)

Few integrative analyses of the structure of agamospermous plant populations have been conducted. Erigeron compositus occurs in montane western North America and comprises both sexual and agamospermous populations. Sexual E. compositus has previously been characterized as outcrossing and predominantly diploid (2n = 18). Agamic E. compositus is usually hexaploid (2n = 54), though counts herein range from 2n = 36 to 2n = 80. Starch-gel electrophoresis, cytology, and analysis of pollen production were used to evaluate variation within and among agamospermous populations. Fifteen enzyme loci were used to identify 24 unique multilocus genotypes in seven populations, an average of 3.4 genotypes per population. Proportion of distinct genotypes per population sample size (GIN) and measures of genetic diversity (D) and evenness (E) are 0.10, 0.48, and 0.61, respectively, which indicate that E. compositus maintains levels of diversity similar to other agamospermous taxa. Most agamospermous populations are mosaics comprising groups of genetically distinct individuals that are frequently distinguished by cytotype and capacity for pollen production. The geographical and ecological separation of sexual and agamospermous populations make it unlikely that gene flow from sexual populations is a direct source of genetic variation in agamospermous populations. Instead, crossing between genetically distinct facultative agamosperms probably accounts for most variation. Genetic and morphological evidence document one such putative crossing event. Agamospermous E. compositus is very similar genetically to sexual E. compositus. Allozyme analysis further shows that genetic variation in agamospermous populations is partitioned among a few highly heterozygous genotypes, whereas sexual populations maintain numerous genotypes of relatively low heterozygosity.     

菊科入侵植物三叶鬼针草的繁殖特征及其与入侵性的关系

三叶鬼针草(Bidens pilosa)是一种危害严重的菊科入侵植物.通过实验观察和人工控制套袋等方法,对其花序开花动态、花粉胚珠比(P/O)、自交亲和性、花粉活力、访花昆虫和种子(瘦果)的萌发率等与繁殖相关的特征进行了研究,探讨了这些繁殖特征与入侵性的关系.三叶鬼针草在10-11月开花,单个花序的花期约为5-6天.每小花的花柱基部有圆筒状的蜜腺环绕.单个花序内可自交亲和,自交结实率和花粉活力均较高,其P/O值为1754.12士29.87.主要访花者为灰蝶科(Lycaenidae)、粉蝶科(Pjerjdae)和茧蜂科(Braconidae)昆虫.三叶鬼针草所具有的灵活交配机制是其入侵成功的重要因素.此外,三叶鬼针草结实量大、种子产生迅速且适于传播,以及种子萌发范围广和短期快速萌发等特性也增强了其入侵性.     

Karyological studies in Sonchus section Muritimi (Asteraceae) from the Iberian Peninsula

MEJÍAS, J. A. & VALDÉS, B., 1988. Karyologiepl studies in Sonchus section Madtimi (Asteraceae) from the Iberian Peninmula. Karyological data support the distinction of S. aquatilis Pourret and S. maritimus L. at the specific level. Karyological data and hybridization experiments support the idea that S. × novocaslcllanus Cirujano has been produced by the hybridization of S. crassifolius Pourret ex Willd. and S. maritimus L.     

Development and characterization of nine new microsatellite markers in Taraxacum (Asteraceae)

This study aims at developing and characterizing new microsatellite primer pairs in Taraxacum officinale auct. to produce polymorphic markers for genetical and evolutionary studies on apomixis in this sexual‐apomictic complex. A total of 24 diploid plants were tested for allelic polymorphism and heterozygosity. Out of nine loci three deviated significantly from the Hardy–Weinberg equilibrium expectations, probably due to the presence of null‐alleles. Successful cross‐species amplification was obtained for all markers in 29 Taraxacum microspecies from five sections.     

Influence of Pluchea lanceolata (Asteraceae) on selected soil properties

Allelopathic interference may operate simultaneously, sequentially, and/or in combination with other mechanisms of interference such as nutrient interference. It is hypothesized that under field conditions, allelopathic plants may cause changes in chemical characteristics of soils in addition to qualitative and quantitative changes in the allelochemical status of soil infested with the allelopathic plant. To test this hypothesis, the perennial allelopathic weed Pluchea lanceolata was selected. A comparative study of P. lanceolata-infested soils, and soils 10, 20, 30, and 40 m away from the weed was undertaken to examine soil characteristics and quantitative and qualitative variation in soil phenolics. Impact of seasonal weather on the biotic and chemical characteristics of P. lanceolata, and quantitative variation in phenolics of weed-infested soils was also studied. Growth experiments were conducted to study the seasonal impact on allelopathic interference of P. lanceolata toward certain crop plants. Results indicate that P. lanceolata influences soil properties in addition to causing variation in soil phenolics. Two-way tests (i.e., analyzing allelopathic and nutrient interference) should be run regardless of whether one is studying allelopathy or nutrient interference and it is important to test allelopathy in all studies dealing with nutrient interference.     

Phylogenetic implications of corolla morphology in subfamily Barnadesioideae (Asteraceae)

The previously insignificant and small South American subtribe Barnadesiinae of tribe Mutisieae has been shown recently to be ancient within Asteraceae. Due to absence of a 22 kb diagnostic chloroplast inversion, plus other features, this subtribe has been elevated to subfamilial status as Barnadesioideae, now containing 90 species in nine genera. Recent cladistic analyses at the generic and specific levels based on morphology and DNA sequences (ITS and trnL intron) have revealed different relationships among taxa of the subfamily. To better understand these conflicts, we analyze specific morphological features of corollas (shape and vascularization) to develop trends (trees) in these features based on minimal structural change (i.e., morphological parsimony), and to compare these with relationships among genera derived from the two recent cladistic analyses. We define six principal types of corollas in Barnadesioideae (tubular, split, double split, ligulate, subbilabiate and bilabiate) and six principal types of corolla vascularization patterns (combinations of presence or absence of central bundles, fusion of adjacent bundles and fusion of bundles at the apex of corolla lobes). In all features we assume character states in Calyceraceae to be ancestral. In corolla shape, from tubular ancestry, we hypothesize two general evolutionary trends within the subfamily: (1) splitting of the tube, and (2) flattening of the tube. In vascularization of corollas, from an ancestral condition of one central and one lateral bundle in each corolla lobe and all traces fused at the apex, we hypothesize four basic trends: (1) gain or (2) loss of lateral vascular traces in each lobe, (3) loss of the central vein, and (4) loss of fusion of traces in lobe apices. These morphological trends allow tests of the two previous phylogenetic hypotheses by (1) counting step changes (following steps in the morphological network) in the two characters on the two competing phylogenetic trees and (2) constructing an index of morphological advancement for each genus (based on morphological trees of the two characters) and correlating these with cladistic distances within the two phylogenies. Results of both tests reveal the molecular phylogeny to be more compatible with evolutionary inferences from the two morphological features. With Fulcaldea excluded, a highly significant correlation is seen between morphological advancement and cladistic distance in the molecular phylogeny.