Flower, seed, and fruit development in three Tunisian species of Polygonum: Implications for their taxonomy and evolution of distyly in Polygonaceae.

Polygonum is the largest genus of Polygonaceae and 5 species are reported in Tunisia. In order to characterized flower, seed, and fruit development in Polygonum, flower and fruit of Polygonium equisetiforme (var. graecum and peyerinhoffi), P. aviculare and P. maritimum, collected from Tunisia, were examined. Flowers are composed of five oblong tepals. P. equisetiforme and P. aviculare have whitish-pink distylous flowers with dimorphism of style, filament and anther height, pollen diameter and stigma size. In contrast, P. maritimum shows white homostylous flowers. The floral vasculature showed that the tepals are inserted in one whorl and their traces arise independently in 3+2 manner. The eight stamens are arranged in a 5+3 manner and the staminal bundles arise independently in the two whorls. The epidermis and endothecium cells width were higher in P. maritimum and the lowest endothecium width was observed in P. aviculare. Polygonum aviculare and P. equisetiforme showed circular pollen with shallow colpi and trilobite pollen shape with deep colpi, while P. maritimum rarely showed shallow colpi. The ovule is anatropous with basal placentation in P. equisetiforme and P. aviculare and apical placentation in P. maritimum. The young seed coat was formed by an endotesta with thick-walled cells, a mesotesta and exotesta with thin-walled cells and a tegmen composed of radially elongated cells. The fruits of the studied species are trigonous with ovate-lanceolate shape. In P. aviculare, the exocarp is thicker compared to the two other species, in P. equisetiforme, the mature exocarp consists of smaller rectangular cells with narrow cavities, and in P. maritimum showed a thinner exocarpIn conclusion, P. equisetiforme and P. aviculare are a typically distylous species from the morphological point of view and we discussed the significance of heterostyly in Polygonaceae. From this first morpho-anatomical study of Polygonum species in North Africa, we can conclude mainly that there is no significant difference between P. equisetiforme var. graecum and var. peyerinhoffi supporting a taxonomic grouping of these two varieties.

Weed Growth Stage Estimator Using Deep Convolutional Neural Networks.

This study outlines a new method of automatically estimating weed species and growth stages (from cotyledon until eight leaves are visible) of in situ images covering 18 weed species or families. Images of weeds growing within a variety of crops were gathered across variable environmental conditions with regards to soil types, resolution and light settings. Then, 9649 of these images were used for training the computer, which automatically divided the weeds into nine growth classes. The performance of this proposed convolutional neural network approach was evaluated on a further set of 2516 images, which also varied in term of crop, soil type, image resolution and light conditions. The overall performance of this approach achieved a maximum accuracy of 78% for identifying Polygonum spp. and a minimum accuracy of 46% for blackgrass. In addition, it achieved an average 70% accuracy rate in estimating the number of leaves and 96% accuracy when accepting a deviation of two leaves. These results show that this new method of using deep convolutional neural networks has a relatively high ability to estimate early growth stages across a wide variety of weed species.

Floral development at multiple spatial scales in Polygonum jucundum (Polygonaceae), a distylous species with broadly open flowers.

Distyly, a special polymorph, has evolved in many groups of angiosperms and has attracted attention since Darwin's time. Development studies on distylous taxa have helped us to understand the evolutionary process of this polymorph, but most of these studies focus on species with narrowly tubular corolla. Here, we studied the floral development of Polygonum jucundum, a distylous species with broadly open flowers, at multiple spatial scales. Results showed that the difference in stigma height between flowers of the two morphs was caused by differences in style growth throughout the entire floral development process. The observed difference in anther heights between the two morphs was because the filaments grew faster in short-styled (SS) than in long-styled (LS) flowers in the later stages of floral development. In addition, the longer styles in LS flowers than in SS flowers was because of faster cell division in the early stages of floral development. However, SS flowers had longer filaments than LS flowers primarily because of greater cell elongation. These results indicate that floral development in P. jucundum differs from that of distylous taxa with floral tubes shown in previous studies. Further, we conclude that the presence of distyly in species with open flowers is a result of convergent evolution.

High water level impedes the adaptation of Polygonum hydropiper to deep burial: responses of biomass allocation and root morphology.

Many studies have investigated the individual effects of sedimentation or inundation on the performance of wetland plants, but few have examined the combined influence of these processes. Wetland plants might show greater morphological plasticity in response to inundation than to sedimentation when these processes occur simultaneously since inundation can negate the negative effects of burial on plant growth. Here, we evaluate this hypothesis by assessing growth of the emergent macrophyte Polygonum hydropiper under flooding (0 and 40 cm) and sedimentation (0, 5, and 10 cm), separately and in combination. Deep burial and high water level each led to low oxidation-reduction potential, biomass (except for 5-cm burial), and growth of thick, short roots. These characteristics were generally more significant under high water level than under deep burial conditions. More biomass was allocated to stems in the deep burial treatments, but more to leaves in the high water level treatments. Additionally, biomass accumulation was lower and leaf mass ratio was higher in the 40-cm water level + 10-cm burial depth treatment than both separate effects. Our data indicate that inundation plays a more important role than sedimentation in determining plant morphology, suggesting hierarchical effects of environmental stressors on plant growth.

[Effect of slice thickness on drying process of Polygonum multiflorum root tuber].

OBJECTIVE: To study the effect of slice thickness on drying process of Polygonum multiflorum root tuber. METHODS: The root tuber of Polygonum multiflorum was sliced with thickness of 2, 5 and 8 mm. Drying experiments were conducted at temperatures of 45, 55, 65 and 75 degrees C. The experimental data were fitted to ten thin-layer drying models to select a suitable model for describing the drying characteristic of Polygonum multiflorum root tuber. Based on thin-layer drying theory, the kinetics parameters of drying process were calculated. RESULTS: The drying processes of Polygonum multiflorum root tuber were consisted of two regions, 1st and 2nd falling rate periods when the slice thickness was thick or the drying temperature was high. Aghbashlo model was the best one to describe its drying behavior. The variation of thickness had significant effect on effective moisture diffusivity (D), but had little effect on activation energy E(a). CONCLUSION: Thin-layer drying theory can be an effective tool for the study of drying behavior of Polygonum multiflorum root tuber. The result provides experimental basis for the quality control of Polygonum multiflorum root tuber drying process.

[Microscopic and polariscopic characteristics of 30 medicinal plants of Polygonum].

Polygonum L. s. str., belonging to Polygonaceae family, is a big genus with abundant medicinal plants. More than 10 plants are specified in Chinese Pharmacopoeia and many local medicinal standards and over 50 species are used as folk medicines. Owing to the similar morphologies and very small flowers and fruits, they are uneasily identified and often confused with each other and misused clinically. In order to provide a basis for identification of Polygonum s. str. plants, a histological study on stems and leaves of 30 species from Polygonum was undertaken by a routine/polarized light microscopy for the first time. The results showed that: (1) the transverse sections of stems of Polygonum are relatively similar, sclerenchyma such as xylem and fibres with strong polarization effects; (2) the surface views of leaves of Polygonum are distinguishable on distributions and types of stomata, with or without attachments (such as glandular hairs/scales or non-glandular hairs) and the polariscopic features of epidermal cell walls, stomata and cell contents. Observed under polarized light, it was found for the first time that stomata on leaf surface of some plants have a Maltese-cross effect with the arms of the cross intersecting at the stomatal opening. As a result, a key combining the microscopic and polariscopic characteristics of the stems as well as leaves was provided for identifying the 30 medicinal plants of Polygonum. The polarized light microscopic method was proven to be one of the quick, simple and effective techniques for the identification of medicinal plants and botanic crude materials.

Phenotypic plasticity and population differentiation in an ongoing species invasion.

The ability to succeed in diverse conditions is a key factor allowing introduced species to successfully invade and spread across new areas. Two non-exclusive factors have been suggested to promote this ability: adaptive phenotypic plasticity of individuals, and the evolution of locally adapted populations in the new range. We investigated these individual and population-level factors in Polygonum cespitosum, an Asian annual that has recently become invasive in northeastern North America. We characterized individual fitness, life-history, and functional plasticity in response to two contrasting glasshouse habitat treatments (full sun/dry soil and understory shade/moist soil) in 165 genotypes sampled from nine geographically separate populations representing the range of light and soil moisture conditions the species inhabits in this region. Polygonum cespitosum genotypes from these introduced-range populations expressed broadly similar plasticity patterns. In response to full sun, dry conditions, genotypes from all populations increased photosynthetic rate, water use efficiency, and allocation to root tissues, dramatically increasing reproductive fitness compared to phenotypes expressed in simulated understory shade. Although there were subtle among-population differences in mean trait values as well as in the slope of plastic responses, these population differences did not reflect local adaptation to environmental conditions measured at the population sites of origin. Instead, certain populations expressed higher fitness in both glasshouse habitat treatments. We also compared the introduced-range populations to a single population from the native Asian range, and found that the native population had delayed phenology, limited functional plasticity, and lower fitness in both experimental environments compared with the introduced-range populations. Our results indicate that the future spread of P. cespitosum in its introduced range will likely be fueled by populations consisting of individuals able to express high fitness across diverse light and moisture conditions, rather than by the evolution of locally specialized populations.

Compartmentalization and ultrastructural alterations induced by chromium in aquatic macrophytes.

The aim of the present study was to identify the sites of accumulation of Cr in the species of macrophytes that are abundant in the Cachoeira river, namely, Alternanthera philoxeroides, Borreria scabiosoides, Polygonum ferrugineum and Eichhornia crassipes. Plants were grown in nutritive solution supplemented with 0.25 and 50 mg l(-1) of CrCl(3)·6H(2)O. Samples of plant tissues were digested with HNO(3)/HCl in a closed-vessel microwave system and the concentrations of Cr determined using inductively-coupled plasma mass spectrometry (ICP-MS). The ultrastructure of root, stem and leaf tissue was examined using transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) in order to determine the sites of accumulation of Cr and to detect possible alterations in cell organelles induced by the presence of the metal. Chromium accumulated principally in the roots of the four macrophytes (8.6-30 mg kg(-1) dw), with much lower concentrations present in the stems and leaves (3.8-8.6 and 0.01-9.0 mg kg(-1) dw, respectively). Within root tissue, Cr was present mainly in the vacuoles of parenchyma cells and cell walls of xylem and parenchyma. Alterations in the shape of the chloroplasts and nuclei were detected in A. philoxeroides and B. scabiosoides, suggesting a possible application of these aquatic plants as biomarkers from Cr contamination.

[Medicinal species of genus Polygonum s. lat. distributed in Anhui Province].

OBJECTIVE: To clarify the resource of medicinal plants of genus Polygonum s. lat. distributed in Anhui Province. METHOD: Conducting field investigation and consulting related specimens and data. RESULT AND CONCLUSION: The distribution, growing environment and medicinal use of 32 taxa have been clarified. A scientific basis for further study for these medicinal plants has been provided.

[Pharmacognostical identification of Polygonum perfoliatum].

In the paper, phamacognostical identification and UV-identification of Polygonum perfoliatum L. were studied.

[Pharmacognostical identification on Chinese drug zhizhuliao].

In this paper, 2 kinds of Zhizhuliao that original plants are Polygonum suffultum Maxim., P. amplexicaule D. Don. var. sinense Forb. et Hemal. are made an initial study on the characteristics, microscopical and physichemical sides. It provides scientific basis for its comprehensive development and ultilization, and to use in clinical.

[Pharmacognostical identification on the Chinese drug quanshen].

In this paper, 5 kinds of Quanshen that original plants are Polygonum bistorta L., P. viviparum L., P. paleacum Wall., P. sphaerostachyum Meisn., P. macrophyllum D. Don. are made an initial study on the characteristics, microscopical and physichemistical sides. It provide scientific basis for its comprehensive development and ultilization, and to use in clinical.