Surface-viewed shoot apex ofAngiopteris lygodiifolia Ros. (Marattiaceae)

Marattian ferns are thought to be an exception to the rule that a single apical cell is always present in the shoot apex of ferns; the occurrence of plural apical initials has been generally accepted for these ferns. However, a contradicting conclusion was reached in this study which examined the apical organization of the shoot ofAngiopteris lygodiifolia Ros., using fresh materials which had not been fixed. Shoot apices were hand-sectioned transversely into thin sections, including the surface layer of the shoot apex, which were observed by differential interference contrast microscopy without staining. In contrast with the generally accepted view, the shoot apex ofA. lygodiifolia was found to usually possess a single apical cell with three cutting faces. The segments cut off from the apical cell are regularly arranged in a helical sequence. The apical cell seems to actually function as an initial cell of the whole shoot apex. The shoot apices, particularly those of plants cultivated in a greenhouse, sometimes show somewhat irregular organization. In extreme cases, no apical cell is recognizable. However, even in these exceptional cases of such apparently irregular shoot apices, plural apical initials are not found.     

Estimation of chronological age for sporophyte maturation in three semi-evergreen ferns in Hokkaido

To elucidate the life cycle time schedule of semi-evergreen ferns at natural sites in Sapporo, the chronological age for sporophyte maturation was estimated from the increase in the number of veins (NV, number of midrib branches) from overwintered to newly expanded leaves. The measurements were conducted on populations ofPolystichum braunii, Polystichum tripteron andDryopteris crassirhizoma at altitudes of 50–650 m on Mt. Teine to compare the interspecific maturation age of sporophytes. The mean age for sporophyte maturation was estimated to be 7.6 yr forP. braunii, 16.5 yr forP. tripteron and 12.6 yr forD. crassirhizoma. The minimum ages (1% fertility rate) for sporophyte maturation ofP. braunii, P. tripteron andD. crassirhizoma were 5.8, 11.0 and 7.9 yr, respectively. The maturation age was shortest forP. braunii and longest forP. tripteron. The maturation age of a species thus seems to differ according to altitude and habitat, and that of the present three species seems to be influenced by the geographical location of the species distribution. Contribution No. 3315 from the Institute of Low Temperature Science, Hokkaido University.     

湖北省蕨类植物分布新记录（一）

武陵山区是中国植物多样性研究的热点地区之一。1988年,中国科学院植物研究所等单位完成了对该地区的第一次生物多样性普查[1],由于行政区域重新划定和交通条件限制等原因,诸多区域未涉及。近期,中南民族大学在国家科学技术部科技基础性工作专项的支持下,再次对该区域(湖北部分)进行了野外调查并采集了大量标本,以相关书籍[2-6]和近期发表的相关调查结果[7-13]为依据,鉴定出一批在湖北省区域内未曾记录的蕨类植物并将陆续予以报道。本文报道了其中的11种1变种,分别隶属于5科10属,凭证标本均存于中南民族大学植物标本馆( HSN),各种类形态特征见图1。     

Heinrichsia cheilanthoides gen. et sp. nov., a fossil fern in the family Pteridaceae (Polypodiales) from the Cretaceous amber forests of Myanmar

Divergence time estimates suggest that most clades constituting the fern family Pteridaceae (Polypodiales) were in existence by the Early Cretaceous. However, fossil evidence to corroborate this remains exceedingly rare. Burmese amber is an important source of new information on the radiation of derived fern lineages during the Cretaceous Terrestrial Revolution. This study describes Heinrichsia cheilanthoides gen. et sp. nov., a fern with suggested affinities to Pteridaceae, based on fertile foliage portions preserved in Early Cretaceous (~100 Ma) amber from Myanmar. Heinrichsia cheilanthoides is characterized by a pinnate‐pinnatifid frond that bears apical, marginal sori protected by a pseudoindusium. Sporangia are of the polypod type and contain tetrahedral‐globose, trilete spores with a striate perine. This discovery provides a new calibration point to test and refine molecular clock‐based concepts of the evolutionary history of the Pteridaceae. Heinrichsia cheilanthoides further substantiates the suggestion that the Cretaceous forests of Myanmar were home to a rich fern flora.     

Flavonoid patterns in athyriaceae and dryopteridaceae

Fifty-one fern species, representative of 11 genera of the Japanese Athyriaceae and Dryopteridaceae (21 species of 6 genera of the former and 30 species of 5 genera of the latter family) have been chemically surveyed for flavonoid glycosides in their fronds, and the results are discussed in connection with their taxonomy and the phylogeny.     

Seasonal variation in the phytomass,chemical composition and nutritional value of Azolla filiculoides Lam. along the water courses in the Nile Delta,Egypt

The present study aims to assess phenological behaviour, phytomass production, chemical composition and nutritional value of Azolla filiculoides in the water courses of the Nile Delta, Egypt. The sampling process was carried out seasonally using twenty‐five plots (each of 1 × 1 m) distributed along 15 irrigation canals and 10 drainage canals in the study area. Sprouting of A. filiculoides had its maximum activity during winter, vegetative growth during spring and summer and withering during autumn. Maximum seasonal phytomass (285.2 g DW m^‐2) was found during spring. The annual mean was significantly higher in drainage canals (278.3 g DW m^‐2) than in irrigation canals (144.4 g DW m^‐2). The concentrations of Ca, Mg and Na in A. filiculoides from drainage canals were significantly higher than in those from irrigation canals. Regarding the type of water courses, there were no significant differences in organic contents and nutritive values between the irrigation and drainage canals. The analysis of growth characteristics indicated that A. filiculoides can grow quite well in drainage canals; its macronutrient (N, Ca, Mg, Na and Fe) contents are high enough to allow it to be used as a bio‐fertilizer. On the other hand, A. filiculoides could be considered as a ‘nutrients and heavy metals remover’ especially in drainage canals for wastewater treatment if the plant is harvested during its maximum phytomass. As feed supplement for animals, this plant could be considered as excellent forage because its high levels of carbohydrate, protein, crude fat, total digestible nutrients and the lower crude fiber contents (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Present,past and future of the European rock fern Asplenium fontanum: combining distribution modelling and population genetics to study the effect of climate change on geographic range and genetic diversity

Background and Aims

Climate change is expected to alter the geographic range of many plant species dramatically. Predicting this response will be critical to managing the conservation of plant resources and the effects of invasive species. The aim of this study was to predict the response of temperate homosporous ferns to climate change.

Methods

Genetic diversity and changes in distribution range were inferred for the diploid rock fern Asplenium fontanum along a South–North transect, extending from its putative last glacial maximum (LGM) refugia in southern France towards southern Germany and eastern-central France. This study reconciles observations from distribution models and phylogeographic analyses derived from plastid and nuclear diversity.

Key Results

Genetic diversity distribution and niche modelling propose that genetic diversity accumulates in the LGM climate refugium in southern France with the formation of a diversity gradient reflecting a slow, post-LGM range expansion towards the current distribution range. Evidence supports the fern''s preference for outcrossing, contradicting the expectation that homosporous ferns would populate new sites by single-spore colonization. Prediction of climate and distribution range change suggests that a dramatic loss of range and genetic diversity in this fern is possible. The observed migration is best described by the phalanx expansion model.

Conclusions

The results suggest that homosporous ferns reproducing preferentially by outcrossing accumulate genetic diversity primarily in LGM climate refugia and may be threatened if these areas disappear due to global climate change.     

Evolution of a unique anatomical precision in angiosperm leaf venation lifts constraints on vascular plant ecology

The main role of leaf venation is to supply water across the photosynthetic surface to keep stomata open and allow access to atmospheric CO₂ despite evaporative demand. The optimal uniform delivery of water occurs when the distance between veins equals the depth of vein placement within the leaf away from the evaporative surface. As presented here, only angiosperms maintain this anatomical optimum across all leaf thicknesses and different habitats, including sheltered environments where this optimization need not be required. Intriguingly, basal angiosperm lineages tend to be underinvested hydraulically; uniformly high optimization is derived independently in the magnoliids, monocots and core eudicots. Gymnosperms and ferns, including available fossils, are limited by their inability to produce high vein densities. The common association of ferns with shaded humid environments may, in part, be a direct evolutionary consequence of their inability to produce hydraulically optimized leaves. Some gymnosperms do approach optimal vein placement, but only by virtue of their ability to produce thick leaves most appropriate in environments requiring water conservation. Thus, this simple anatomical metric presents an important perspective on the evolution and phylogenetic distribution of plant ecologies and further evidence that the vegetative biology of flowering plants—not just their reproductive biology—is unique.