Effect of oil on recruitment from the seed bank of two tidal freshwater wetlands

The effect of oil spills on the recruitment of freshwater tidal wetland species was determined using soil seed bank samples collected in early March from two New Jersey Delaware River marshes. Samples were exposed to simulated tidal cycles 0 (2 days), 2 and 4 wk after soil was collected; 0 wk samples were treated before germination began. Oil treatment significantly reduced survival to I May (end of study) of Acnida cannabina and Bidens laevis, the dominant species, as well as number of species per sample and height of B. laevis. Total perennial seedlings, present in low numbers, also showed significant reduction with treatment. However, during the course of the study, Peltandra virginica recruitment and survival were not reduced by oil treatment and recruitment of Sagittaria latifolia appeared enhanced. There was no consistent pattern regarding which treatment time produced the greatest effect. Interactions (site, treatment, time) were generally not significant. Because these tidal freshwater wetlands and seed banks are dominated by annuals, reduction in seedling numbers and growth could substantially alter vegetation patterns. Timing of oil spills would be important, but impact would depend on species composition of the seed bank and colonizing vegetation, dispersal of seeds into the site, and germination requirements.     

Taxonomic significance of the inner structure of the ovary in the genusImpatiens (Balsaminaceae)

The inner structure of the ovary inImpatiens was examined from the viewpoint of taxonomy, based on the materials obtained during the 1979 Botanical Expedition to Thailand. The species studied areI. kerriae, I. larsenii, I. hongsonensis, I. psittacina, I. salaengensis, I. charanii, I. kanburiensis andI. macrosepala. It is worthy of special mention that they are all characterized by 4 lateral sepals, large round outer sepals, a nipple-like short spur of the lip and connate wing petals. Contrary to the prevailing information about the ovary ofImpatiens, these Thai species were found to have 4-locular and 4-carpellate ovaries. The arrangement and the number of ovules in a loculus show a tendency of reduction from biseriate to uniseriate and from several to single or none. The species of more advanced type have smaller numbers of ovules and often sterile loculi of the ovary, as represented byI. macrosepala. The types of ovule development were proved to correspond to the degree of specialization of floral characters. Supported by a Grant in Aid of Scientific Research of Ministry of Education, No. 404126 and No. 504352, and partly reported at the Meeting of the Japan Society of Plant Taxonomists in March 1981.     

Genetic instability of anthocyanin production in Impatiens balsamina

Summary It is established that in a naturally occurring variegated Impatiens balsamina the phenotype is determined by a mutable allele p ^m, of an anthocyanin-governing gene P ^r. The special allele produces an acyanic phenotype like the stable recessive p but undergoes frequent changes to P ^r in somatic and germinal cells (causing a variegated phenotype in the former) when a controlling element M is also present in the genome. It is suggested that p ^m is a repressed p ^r and M acts either by removing or inactivating whatever causes that repression. Such changes proceed in a unique fashion: either p ^m changes to p ^r or to an intermediate labile condition P which then changes to p ^r, resulting either in dark or pale, or dark super-imposed on pale, sectors; a reverse situation was not observed. Colourless plants which occasionally appear in unstable lines seem to be due to loss of M although changes ofp ^m itself cannot be ruled out at present.     

Variation in nectar volume and composition of Impatiens capensis at the individual,plant, and population levels

Although the volume and chemical composition of nectars are known to vary among plant species and to affect pollinator response to plants, relatively little is known of the variation in volume, and sugar and amino acid composition within species. We collected nectar from Impatiens capensis in a nested design: three flowers from each of three plants from each of three populations. This design enabled us to quantify variation within individual plants, among plants within populations, and among populations. Using high performance liquid chromatography, we analyzed the sugar and amino composition of the 27 flowers. Analysis of variance showed that none of the parameters (volume, concentrations of three sugars and 24 amino compounds) varied within individuals. Variation in nectar volume was not significant among plants but was nearly significant among populations. Of the three sugars detected (sucrose, glucose, and fructose), the only significant variation was that of sucrose among populations. Concentrations of 12 amino compounds varied significantly at the plant level while 7 amino compounds varied among populations. The results indicate that: (1) pooling of nectar samples from flowers of individual plants can be an acceptable methodology for those seeking to understand within species variation; (2) amino compounds appear to vary more than either volumes or sugar concentrations; (3) future studies should assess how much of the observed variation is due to genetic versus environmental differences; (4) additional studies should examine the geographic variation in nectar parameters and pollinators of I. capensis in order to assess the role different pollinators play in shaping nectar composition.     

十四种凤仙花属植物种皮微形态特征及其分类学意义

通过扫描电镜对凤仙花属(Impatiens)14种植物的种子表皮微形态特征进行了观察。根据种皮表面纹饰及衍生物的特点,将该属植物的种皮微形态特征划分为4种类型,即光滑型、颗粒型、网状型和隆起型,后两者又可细分为若干亚型,其中负网状亚型和网状-丘状隆起亚型为首次报导。研究表明,14种凤仙花属植物种子表皮微形态特征差异显著,它们作为属内种的分类鉴别特征具有重要价值;种子表皮的微形态学特征与其植物体的部分表型特征具有相关性,在一定程度上反映了属内类群的分化。     

广西凤仙花属(凤仙花科)一新变种——瑶山凤仙花

描述了中国广西凤仙花科Balsaminaceae凤仙花属Impatiens一新变种——瑶山凤仙花I. macrovexilla var. yaoshanensis S. X. Yu, Y. L. Chen ＆ H. N. Qin。该变种与原变种不同在于叶卵圆形或卵状矩圆形, 侧生萼片全缘, 翼瓣的上部裂片全缘, 翼瓣背部的小耳明显, 此外花粉形态和种皮纹饰等性状也支持该变种的建立。     

Stream invertebrate diversity reduces with invasion of river banks by non‐native plants

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