山东石松类和蕨类植物新记录

该研究报道了山东地区4种1变种和1变型石松类和蕨类植物新记录,分别是石松类的伏地卷柏( Sel-aginella nipponica Franch. et Sav.),蕨类的小戟叶耳蕨[Polystichum hancockii (Hance) Diels]、阔羽贯众(Cyrtomium yamamotoi Tagawa)、粗齿阔羽贯众[C. yamamotoi Tagawa var. intermedium (Diels) Ching et Shing ex Shing]、小羽贯众[C. fortunei J. Sm. f. polypterum (Diels) Ching]、远叶瓦韦[Lepisorus ussuriensis var. distans (Makino) Taga-wa]。同时采用扫描电镜对其孢子形态进行了观察,该研究结果为其分类鉴定提供了孢粉学依据。     

普通针毛蕨颈卵器和卵的发育

蕨类植物卵发生是有性生殖研究的重要内容。真水龙骨类II的卵发生尚无人研究, 本文对该类群中的普通针毛蕨(Macrothelypteris torresiana)卵发生过程进行了光镜和透射电镜研究。结果显示: 卵细胞刚形成时, 与腹沟细胞紧密相连, 随着卵进一步发育, 卵细胞和腹沟细胞之间逐渐形成分离腔, 但孔区处卵细胞和腹沟细胞始终相连。随后, 卵细胞上表面有不定型物质堆积在质膜外, 形成一层加厚的卵膜, 孔区处没有卵膜覆盖的位置最后形成受精孔。在卵发育后期, 卵细胞核变得不规则, 近成熟时卵核产生大量核外突。卵发育过程中卵膜的出现、受精孔的产生以及核外突等特征, 与进化的真水龙骨类中其他蕨类植物的卵发生研究结果相似, 与薄囊蕨类中原始基部类群的卵发生现象有显著差别。由此可见, 普通针毛蕨属于进化类型。依据卵发生中卵膜和受精孔等特征推测原始薄囊蕨类经过里白类、桫椤类, 最终演化为水龙骨类。     

湖南蕨类植物区系新资料（Ⅱ）

报道了湖南蕨类植物区系新记录20种（隶属5科7属）;它们是毛足铁线蕨 (Adiantum bonatianum)、多芒复叶耳蕨（Arachniodes aristatissima）、狭长复叶耳蕨（A. attenuata）、粗裂复叶耳蕨(A. grossa)、南川复叶耳蕨(A. nanchuanensis)、黑鳞复叶耳蕨（A. ningrospinosa）、缩羽复叶耳蕨(A. reducta)、长刺复叶耳蕨（A. setifera）、节肢蕨（Arthromeris lehmannii）、多羽节肢蕨（A. mairei）、上斜刀羽耳蕨（Polystichum assurgentipinnum）、深裂耳蕨（P. incisopinnulum）、前原耳蕨（P. mayebarae）、假线鳞耳蕨（P. pseudosetosum）、边果耳蕨（P. shimurae）、钻鳞耳蕨（P. subulatum）、等基贯众（Cyrtomium aequibasis）、尖齿肋毛蕨（Ctenitis dentisora）、梵净肋毛蕨（C. wantsingshanica）、琼崖舌蕨（Elaphoglossum mcclurei）。     

2-deoxy-3-epiecdysone from the fern Blechnum vulcanicum

2-Deoxy-3-epiecdysone and ecdysone were isolated from fronds of the fern Blechnum vulcanicum. The structure and stereochemistry of the epiecdystero     

Assessment of gene copy number in the homosporous fernsCeratopteris thalictroides andC. richardii (Parkeriaceae) by restriction fragment length polymorphisms

Homosporous ferns are generally considered polyploid due to high chromosome numbers, but genetically diploid since the expression of isozymes is generally controlled by a single locus. Gene silencing over evolutionary time is one means by which this apparent contradiction can be explained. A prediction of this hypothesis is that silenced gene sequences still reside in the genomes of homosporous ferns. We examined the genomes ofCeratopteris richardii andC. thalictroides for sequences which are similar to expressed gene sequences. Genomic DNA blots hybridized withC. richardii cDNA clones showed that the majority of these clones detected multiple fragments, suggesting that most gene-like sequences are duplicated inCeratopteris. Hybridization signal intensity often varied between fragments of the same size between accessions, sometimes dramatically, which indicates that not all sequences are equivalent, and may represent the products of silenced genes. Observed reciprocal differences in intensity could be due to reciprocally silenced genes. In addition, an unusual segregation pattern for one locus followed by one probe may indicate homeologous chromosome pairing and segregation.     

Ultrastructural interpretation of the Late Cretaceous megaspore Glomerisporites pupus and its associated microspores

The ultrastructure of the Late Cretaceous (Santonian–?early Campanian) megaspore Glomerisporites pupus and its associated microspores has been examined in an attempt to resolve a number of problems concerning the interpretation of their morphology. The new observations presented are based on an analysis of entire, fragmentary, and thin-sectioned specimens under scanning and transmission electron microscopes. These add to, and partly correct, previous observations on this taxon. They include the following: (1) The exine of the megaspore consists of thin, homogeneous, outer undulating and inner electron dense layers, with a thicker zone of spongy structure in-between. (2) The perispore (or perine) of the megaspore comprises four layers, in order towards the exterior: loose filamentous, dense filamentous, vacuolate, and columnar. (3) This is completely enclosed by a thick mat of hairs, which appears to be attached to the underlying perisporal layers by means of connections with a few of the “spines” that originate from the dense filamentous zone, and with some elements of the columnar perine. (4) The tripartite neck (acrolamella) of the spore, which is hidden beneath the mat of hairs, is predominantly an extension of the dense filamentous and vacuolate layers, but also involves the columnar layer, especially in the lower part. (5) Some of the numerous small floats that are embedded in the mat have hairs originating from them. (6) Both long tangled and circinate hairs surround the perispore of the microspores. (7) The exine of the microspore was at least partly attached to the perispore when the organ was viable. (8) It comprises four zones that vary in structure and electron density. These facts and comparisons made with other megaspores and their associated microspores confirm evolutionary links between G. pupus and several taxa included within the Salviniaceae (Azolla, Parazolla, Salvinia) and possible ancestors of this group (the parent plants of Ariadnaesporites and Capulisporites).     

Tree Ferns in the Interior and at the Edge of a Mexican Cloud Forest Remnant: Spore Germination and Sporophyte Survival and Establishment1

The three most common tree fern species in a Mexican montane cloud forest fragment (Alsophila firma, Lophosoria quadripinnata and Sphaeropteris horrida) were selected for laboratory and transplant experiments. The objectives were: (1) to determine the percentage of spore germination and gametophytes producing sporophytes, and (2) to compare early establishment of sporophytes at the edge and in the interior of the forest. Percent spore germination varied between 16 and 86 percent, and the number of gametophytes that produced sporophytes was high (>50%). Survival and growth of sporophytes differed between species and habitats. Survival was greater at the edge than in the forest interior for Lophosoria, but it was similar for Alsophila and Sphaeropteris. Number and length of fronds were higher at the forest edge for individuals of Alsophila and Lophosoria, but not for Sphaeropteris. RGR was higher at the forest edge than in the forest interior for sporophytes of the three species. This study suggests that the forest edge is an appropriate habitat for establishment of Alsophila and Lophosoria, but Sphaeropteris is apparently a forest interior species.     

A human-induced downward-skewed elevational abundance distribution of pteridophytes in the Bolivian Andes

Aim  To search for differences in the spatial variability of upper and lower elevational distribution limits of tropical ferns, based on the assumption that these are determined to different degrees by biotic and abiotic factors.
Location  The Yungas biogeographical region, in the Bolivian Andes.
Methods  From a data base of > 25,000 herbarium records, we analysed the skewness of the elevational distribution of 220 montane pteridophyte species, each with  15 records. Additionally, we compared the spatial variability of upper and lower elevational range limits of ferns in 351 plots of 400 m² each along four elevational transects separated by 15–450 km.
Results  Individual species showed variable elevational distribution patterns, ranging from symmetric to asymmetric, i.e. downward and upward skewed, but overall there was a statistically significant trend towards asymmetric distributions with abrupt upper limits and diffuse lower limits. This trend, however, was almost exclusively due to terrestrial species occurring at and above the current timberline. The analysis of the elevational transects revealed no significant trends.
Main conclusions  The downward-skewed distributional abundance of terrestrial, open-country ferns near the timberline appears to be a result of the extensive forest destruction that has lowered the timberline in the high Andes by 500–800 m, opening up habitats for a restricted suite of species. Our study shows that a limited number of species can cause a general trend in the overall data set, and that failure to extract these data may result in unsupported conclusions, in our case to assign a greater importance to biotic and abiotic factors in the elevational limitation of plants at lower and upper elevations, respectively.