Anatomical aspects of field ectomycorrhizas on Polygonum viviparum (Polygonaceae) and Kobresia bellardii (Cyperaceae)

 Root systems of the herbaceous species Polygonum viviparum and Kobresia bellardii were excavated from an alpine site in the Rocky Mountains, Colorado, and processed for microscopic examination. Several ectomycorrhizal morphotypes were present on root systems of both species;K. bellardii often had complex clusters of mycorrhizal roots present. A mantle and Hartig net were present on all mycorrhizal root tips processed. The Hartig net was confined to the epidermis, and the parenchyma cells of this layer were radially elongated, vacuolated and contained densely staining inclusions. Intracellular hyphae and structures typical for vesicular-arbuscular mycorrhizas were never observed. Both herbaceous species, therefore, had ectomycorrhizal associations comparable to those described for woody angiosperm species. Accepted: 14 February 1998     

Altitudinal variations in flower and bulbil production of an alpine perennial, Polygonum viviparum L. (Polygonaceae)

Two opposite views exist regarding sexual versus asexual reproductive performance of Polygonum viviparum . One suggests that increasing altitude favors flower production, while the other suggests that increasing altitude increases bulbil production. In this study, we present an investigation of the reproductive performance of 13 populations of P. viviparum on the Qinghai–Tibet Plateau (QTP). Our results show that, with increasing altitude, the height of inflorescence and total number of flowers and bulbils decrease significantly, but there is no significant effect on bulbil and flower number. In addition, there is a weak correlation between the proportion of flowers per population and altitude in our study sites due to the exception population 12, which is in a disturbed habitat. We conclude that more resources might be allocated to flowers in populations at higher altitudes, indicating the importance of sexual reproduction over asexual reproduction in alpine plants of QTP.     

Nomenclatural changes in Polygonum section Echinocaulon (Polygonaceae)

As a result of comprehensive systematic study onPolygonum sectionEchinocaulon, three new nomenclatural changes are made:P. clarkei stat. et nom. nov.,P. subsagittatum stat. nov., andP. senticosum var.sagittifolium stat. nov.     

Ultrasculpture of achene surface in Polygonum section Polygonum (Polygonaceae) in Russia

Based on SEM examination of 47 specimens and 33 species from Russia and Europe, this is a survey of achene surface ultrasculpture in 6 subsections of annual species of Polygonum. Early and late achenes detected in most species possess sound distinctions in achene shape, size, color and exocarp structure. Late achenes with early and fast seed germination preserve exocarp structure typical for premature achenes of both types: thin colorless walls and vast cavities, thin cuticle and insignificant wax deposits. Early achenes destined for long-term preservation in soil are thickwalled and covered with thick and smooth cuticles and wax layers. The structure of achene surfaces changes substantially during maturing, especially in early achenes: coarse or foveo-rugulate background becomes minutely rough, foveosmooth or minutely reticulate. Verrucae are not obligatory ornaments. Depending on their location and arrangement of exocarp cells the surface is evenly verrucate (subsect. Paatula Tzvel.), linear-verrucate (subsect. Salsuginea Tzvel.) or striate-verrucate (subsect. Humifusa Tzvel., most species in subsect. Polygonum ). Smooth and glossy achenes are more common in permanently wet environments (subsect. Maritima Tzvel., Arenaria Tzvel., P. arenastrum and P. calcatum from subsect. Polygonum ). In places with fluctuating availability of water the achenes have heavier sculpturing and thicker cutin and wax coverings. A broad range of surface sculptures in some species and their similarity across taxonomically distant taxa decrease the value of the characters for taxa identification.     

Distyly in Polygonum jucundum Meisn. (Polygonaceae)

Pollen grains of tribe Sanguisorbeae (Rosaceae, Rosoideae) were examined using scanning electron microscopy to identify useful characters, test taxonomic and phylogenetic hypotheses among genera, and elucidate pollen character evolution based on a molecular phylogeny. Aperture number, aperture structure, pollen shape, and exine sculpturing were variable within Sanguisorbeae and were used to delineate six pollen types. Four types (I–IV) were observed only in subtribe Sanguisorbinae whereas two types (V–VI) were found only in subtribe Agrimoniinae. Pollen grains of tribe Sanguisorbeae were generally subprolate to spheroidal in shape, had operculate or pontoperculate apertures, and had three apertures, except for Margyricarpus (tetraperturate). Exine sculpturing within Sanguisorbinae represented variations of striate, verrucate, rugulate, and perforate patterns often with microechinate sculpturing. Striate exine patterns and prolate shapes characterized the pollen of the Agrimoniinae, except for the microechinate-verrucate pattern and subprolate to spheroidal shapes observed in Hagenia. Pollen characters are most useful at the generic level and, when mapped on to a molecular phylogenetic tree of the tribe, are concordant with a monophyletic Agrimoniinae and a clade comprising Margyricarpus + Acaena + Polylepis + Cliffortia + Sanguisorba in the Sanguisorbinae. Outgroup comparison indicated that operculate colpi, three apertures, and polymorphism for striate or microverrucate exines represented primitive states for tribe Sanguisorbeae.     

中国蓼属萹蓄组植物果实形态的研究

应用解剖镜和电子扫描显微镜对中国产蓼属萹蓄组Polygonum sect.Polygonum 16种1变种及1变型植物的果实形态进行了研究。发现该组5种一年生植物的果实具有两型性,即有长、短两种果实类型。短果类型为卵形,具三棱,包于宿存花被内或与花被近等长,呈黑褐色。在解剖镜下观察到其表面具小点、无光泽,而在电子扫描显微镜下观察到其表面具有散乱分布或排列成行的瘤状颗粒;长果类型为狭卵形,具三棱,长于宿存花被,黄褐色或淡黄绿色,在解剖镜下观察到其表面平滑、有光泽,而在电子扫描显微镜下观察到其表面上部具有散乱分布的瘤状颗粒,中、下部则具不规则洼点、星花状褶皱或浅波纹状。果实具两型性的植物有萹蓄P.aviculare、乌鲁木齐萹蓄P.urumqiense、展枝萹蓄P.patulum、直立萹蓄P.avicularef.erectum和尖果萹蓄P.rigidum。果实微形态可分为两种类型：1.果实表面无瘤状颗粒或疣状突起、有光泽,此类型又可以分为2种亚类型：（1）果实表面平滑、浅波纹状,如岩萹蓄P.cognatum、松叶萹蓄P.acerosum和帚萹蓄P.argyrocoleum;（2）果实表面具浅洼点或洼点,如铁马鞭P.plebeium和针叶萹蓄P.polycnemoides。2.果实表面有瘤状颗粒或疣状突起,无或具微光泽,此类型又可分为4种亚类型：（1）果实表面具疣状突起,如圆叶萹蓄P.intramongolicum.;（2）果实表面具散乱分布的瘤状颗粒,如普通萹蓄P.humifusum和展枝萹蓄的短果;（3）果实表面具有纵行排列的瘤状颗粒,如萹蓄和乌鲁木齐萹蓄的短果;（4）果实表面上部具散乱分布的瘤状颗粒,中、下部具不规则洼点、星花状褶皱或浅波纹状,如萹蓄、展枝萹蓄、直立萹蓄和尖果萹蓄的长果。因此果实两型性和果实微形态特征对蓼属萹蓄组种、变种的鉴定具有较大的分类学价值。基于果实微形态特征以及其他形态特征,确定了新种晖春萹蓄Polygonum huichunense F.Z.Li,Y.T.Hou＆C.Y.Qu,同时恢复褐鞘萹蓄Polygonum aviculareL.var.fusco-ochreatum（Kom.）A.J.Li为原种,即Polygonum fusco-ochreatum Kom.。     

A taxonomic revision of Calotropis (Asclepiadaceae)

The genus Calotropis of the tribe Asclepiadeae of Asclepiadaceae subfamily Ascle-piadoideae is revised throughout its Tange in tropical and subtropical Africa and Asia. The three species recognized are keyed out, illustrated and described with appropriate bibliography, synonymy, notes on ecology, distribution and uses. Distribution maps for the species are provided. The taxonomic position of the genus is discussed and a historical review is provided.     

A revision of the genus Oxytheca Nutt. (Polygonaceae)

The genusOxytheca of western North America and temperate South America consists of seven species which are keyed, described, discussed, illustrated, and mapped. They are divided among sect.Oxytheca, sect.Acanthoscyphus stat. & comb. nov., and sect.Neoxytheca sect. nov.Oxytheca dendroidea subsp.chilensis is given as a new combination, whileO. parishii var.cienegensis andO. parishii var.goodmaniana are described as new. The history and relationships of the genus are discussed. It is retained as distinct fromEriogonum and is thought to have arisen from the larger genus nearE. spergulinum, E. parishii, andE. apiculatum in subgenusGanysma. Cytological data indicatedn= 20.     

An unusual homoisoflavanone and a structurally-related dihydrochalcone from Polygonum ferrugineum (Polygonaceae)

The homoisoflavanone 5,7-dihydroxy-6-methoxy-3-(9-hydroxy-phenylmethyl)-chroman-4-one (1) and its structurally related 2',4',6'-trihydroxy-3'-methoxy-alpha-hydroxymethyl-beta-hydroxy-dihydrochalcone (2) along with the known pashanone (3), flavokawin B (4) and cardamonin or alpinetin chalcone (5) pinostrobin (6) and 5,8-dimethoxy-7-hydroxychroman-4-one (7) were isolated from dry leaves of Polygonum ferrugineum (Polygonaceae). To our knowledge, this is the first report of the isolation of a homoisoflavanone from the Polygonum genus and the Polygonaceae family, and could be an important chemotaxonomic finding. In addition, the pattern of substitution of this homoisoflavanone is different from others previously reported.     

Vandiemenia ratkowskiana Hewson (Marchantiophyta): a revised description and reassessment of its taxonomic status

Abstract

The endemic Tasmanian hepatic Vandiemenia ratkowskiana Hewson, originally referred to the family Vandiemeniaceae (Marchantiophyta), is restudied taxonomically. The rhizoids, female plants, calyptrae and sporophytes are described for the first time. These features are closest to those of Metzgeria (Metzgeriaceae) and support the placement of Vandiemenia within the Metzgeriaceae.     

Taxonomy of the Polygonum douglasii (Polygonaceae) complex with a new species from Oregon

The taxonomy of the Polygonum douglasii complex is revised. A summary of relevant taxonomic information is provided, along with a key to the species and subspecies, plus typification, synonymy, discussion, distribution, and ecology. Morphology and micromorphology of stems, leaves, perianth, pollen, and achenes are analyzed and illustrated. Based on these data, 12 species and two subspecies are recognized. A new species, P. gabrielae, is described and illustrated from Oregon.     

A taxonomic revision of the Phreodrilidae (Oligochaeta)

Seven of the 20 former species of the Phreodrilidae have been examined. Information derived from a study of this material has necessitated a re-assessment of the interpretations of some of the anatomical features formerly employed in the separation of genera. As a result, all of the known species are merged in the single genus Phreodrilus with seven subgenera, 17 species and two taxa recognizable only as unidentifiable phreodrilids.     

超积累植物水蓼吸收锰的生理与分子机制

水蓼(Polygonum hydropiper)是一种新近发现的锰超积累植物.本文通过营养液模拟试验,研究了锰在水蓼细胞中的分布与化学形态特征,以及锰胁迫下水蓼的生理生化响应机制.结果表明:锰在水蓼叶片非活性代谢部分(细胞壁和液泡)的积累是其解毒耐锰的主要机制之一;水蓼叶片中的锰大部分以水溶性有机盐或草酸锰的形态存在;在锰浓度处理为8 000 μmol/L时,叶绿素a含量显著降低,而在其它处理条件下,叶绿素a无明显变化;在锰处理≤5000 μmol/L时水蓼叶片的细胞膜还没有受到明显伤害;水蓼叶片的可溶性蛋白含最随锰处理浓度小同而变化,说明植物在代谢和结构上发生了调整;随锰处理浓度的增加,水蓼叶片SOD和POD活性提高,保护酶活性的提高义可清除活性氧自由基,这是水蓼耐高锰和累积锰的一种生理响应机制.     

Pollen morphology of the genera Polygonum s. str. and Polygonella (Polygoneae: Polygonaceae)

The pollen of 30 taxa (27 species, one subspecies and two varieties) in two genera, viz Polygonum s. str. and Polygonella was investigated with LM and SEM, and some selected taxa with TEM. In all genera investigated the pollen is prolate to spheroidal, and the aperture is mostly tricolporate, rarely panto-hexacolporate (especially Polygonum section Polygonum). The exine sculpturing pattern is the most variable feature. Three types of exine can be recognized. Type 1 (Avicularia-Type, sensu Hedberg) - All species of section Polygonum and section Tephis share the smooth tectate exine with spinules, sometimes the surface is more or less rough (Polygonum afromontanum in section Tephis). Type 2 (Pseudomollia-Type, sensu Hong) - Pollen of Polygonum molliaeforme (section Pseudomollia) has the exine, which is verrucose on both poles and nearby the mesocolpium, and mostly psilate around the ectoaperture. Type 3 (Duravia-Type, sensu Hedberg) - Pollen grains of Polygonum section Duravia and Polygonella have the exine which is semitectate-reticulate at the mesocolpium and the poles, and rugulate/reticulate or sometimes foveolate with microspinules around the ectoapertures. The pollen grains in four taxa (viz Polygonum section Pseudomollia, P. section Duravia and genus Polygonella) have a well-marked dimorphism of the ektexine, which is considered to be a synapomorphic condition. The differences of pollen grain between the genus Polygonella and Polygonum section Duravia are almost non existent and clearly interrelated. It is therefore postulated that the similarity in pollen of both taxa is not the result of convergency, but is interpreted as a homology. It is noteworthy that the pollen of Polygonum molliaeforme (section Pseudomollia) appears as intermediate between the Avicularia-type and the Duravia-type, and is well supported the value of separated section for its own. Additionally, in TEM, some exine ultrastructures (e.g. columellae, foot layer, endexine) appear to be valuable characters for comparison between/among taxa. The systematic potentialities of the pollen data of the studied taxa at various systematic levels are also discussed.