14种剑蕨属植物的孢子形态特征及其系统分类学意义

利用扫描电子显微镜对水龙骨科(Polypodiaceae)剑蕨属(Loxogramme)14种植物的孢子形态和表面纹饰进行了观察。结果显示:剑蕨属的孢子具有单裂缝和三裂缝两种类型,个别物种具有中间过渡类型。剑蕨属的孢子纹饰为蠕虫状或浅波纹状。经比较发现,具三裂缝孢子的物种通常植株较小,而具单裂缝的种类则通常植株较大。从进化的角度来看,三裂缝孢子为原始类型,单裂缝孢子为进化类型,因而从孢子形态特征的角度支持剑蕨属为水龙骨科基部类群。     

中国蕨类植物孢子形态的研究 Ⅱ. 中国蕨科

利用扫描电镜对国产中国蕨科Sinopteridaceae植物9属61种6变种的孢子进行了观察。结果表明,该科植物的孢子可分为3种类型：(1)孢子球形,三裂缝;周壁较厚,疏松地包在孢子之外;外壁光滑,表面纹饰由周壁形成,呈网状、嵴状、刺状或皱状。除金粉蕨属Onychium和珠蕨属Cryptogramma外,该科其他属的植物都具此类型孢子。(2)孢子钝三角形,三裂缝;周壁较薄,由周壁和外壁共同形成表面轮廓,表面具疣状或颗粒状纹饰。具此类型孢子的只有珠蕨属。(3)孢子钝三角形,三裂缝,沿裂缝两侧各有一脊状隆起或瘤状纹饰;周壁薄,由外壁形成表面纹饰的基本轮廓;具赤道环、近极脊和远极脊。具此类型孢子的只有金粉蕨属。另外,从孢粉学的角度对该科的分类和系统演化进行了探讨。     

诸广山地区石松类和蕨类植物资源及区系研究

通过多次野外调查及资料整理,对诸广山地区石松类和蕨类植物的资源组成、地理成分、生态环境等方面进行了分析研究。结果显示:(1)诸广山地区共有石松类和蕨类植物37科、87属、249种,优势科为鳞毛蕨科、水龙骨科、金星蕨科、蹄盖蕨科、凤尾蕨科,优势属为鳞毛蕨属、凤尾蕨属、复叶耳蕨属、卷柏属,单种科有12个,单种属有39个,这些丰富度高的蕨类中既有古老孑遗种又有新生代年轻种,反映了该区蕨类植物的古老性与延续性。(2)从分布区类型来看,该区石松类和蕨类植物区系中以热带性质的科和属占绝对优势,分别占除世界分布类型外总科、属数的89. 3%和77. 6%,以泛热带分布类型为主。但种的地理成分复杂,温带成分略显优势,占50. 6%,以东亚分布类型为主,中国特有分布种占23. 3%;热带成分的种占26. 1%,以热带亚洲分布类型为主。表明该蕨类植物区系具有热带亲缘性,是明显的热带向温带过渡地段。(3)该区以土生蕨类群落类型为主,树生蕨类与石生蕨类随海拔升高而增多,物种丰富度在800-1 500 m处最高。     

海南岛吊罗山蕨类植物的多样性及其保育

对海南岛吊罗山的蕨类植物进行了专题研究。吊罗山有蕨类植物 4 3科 10 0属 2 13种及 4变种 ,其中 5种为海南新记录。蕨类物种密度高达 5 5 .8种 / 10 0km2 ,为海南蕨类多样性中心之一。该地蕨类植物区系以水龙骨科和膜蕨科为优势科 ,表现出明显的热带性质 ,热带分布的科、属、种分别达到 10 0 %、93.2 %和 95 .3%。在垂直分布上 ,蕨类植物的生态特点与植被类型相关 ,随着海拔升高 ,阳生性蕨类减少 ,阴生性蕨类、附生与石生蕨类增多 ,蕨类物种多样性在海拔 6 0 0～ 10 0 0m地段最为丰富。按照 2 0 0 1年IUCN红色名录等级及标准评估 ,在海南岛范围内 ,吊罗山有 36种受威胁蕨类植物 ,其中 6种为极危物种 ,13种为濒危物种 ,17种为渐危物种 ,这 36种受威胁蕨类中有 8种属于国家II级保护植物。导致这 36种蕨类植物受威胁的原因主要有 :人为直接破坏、生境旱化和分布区限制     

祖先性状重建法揭示铁线蕨属植物孢子表面纹饰的形态多样性及其演化

蕨类植物孢子表面的纹饰形态复杂多样, 在分类学和古生物学研究中具有重要意义, 目前探索祖先性状演化常用形态学与系统发育学结合的方法。本文选取一回羽叶铁线蕨类植物为材料, 用扫描电子显微镜观察其孢子形态, 用5个叶绿体基因序列构建系统树, 用最大似然法和最大简约法来分析孢子性状的演化。结果表明: 一回羽叶铁线蕨类的孢子纹饰有5种类型, 即光滑、粗糙、颗粒、疣状及瘤状; 这一类群的祖先孢子纹饰有很大的可能是瘤状纹饰; 疣状纹饰可能是由瘤状纹饰演化而来; 孢子纹饰由简单向复杂演化, 越进化的物种其孢子纹饰越复杂。     

广西蕨类植物孢子形态的研究Ⅰ.水龙骨科

该文是广西蕨类植物孢子形态研究的第一部分。首次利用光学显微镜和扫描电子显微镜对广西产水龙骨科6属9种植物的孢子形态进行了观察研究。对每个种的孢子形态特征及表面纹饰进行了描述。水龙骨科6属9种植物孢子都为单裂缝类型孢子,孢子外壁表面具有皱状、细孔状、蠕虫状、瘤状、光滑、索状条纹和颗粒状纹饰7种纹饰类型。讨论了各属、种问的差异,为水龙骨科系统分类及孢粉学研究提供资料。     

中国水蕨属孢子形态及其系统学意义的研究

利用扫描电镜和透射电镜技术对我国产水蕨属2种的孢子形态进行了观察,对2种的形态结构进行了描述。本属孢子是同型孢子蕨类植物中最大的孢子,三裂缝,肋状纹饰,由外壁形成纹饰的轮廓;具较薄的周壁,在高倍放大的情况下呈颗粒或杆状,我们从孢子形态角度,支持水蕨作为一个独立的科,它与海金沙科的非洲蕨属（Mohria)的亲缘关系较近,是介于海金沙科和裸子蕨科之间蕨群。     

湖北恩施地区蕨类植物区系研究

蕨类植物是森林植被中草本层的重要组成部分,对森林的生长发育有重大影响。本研究在搜集文献、野外调查和采集标本的基础上,对湖北恩施地区蕨类植物区系成分及特点进行研究。结果显示:(1)恩施地区蕨类植物共有39科96属380种,其中中国特有种106种;该地区蕨类植物起源古老,物种分化水平较高,优势科属明显、物种丰富、组成多样,是蕨类植物物种多样性的典型代表地区之一。(2)该地区稀子蕨属、荚果蕨属、黔蕨属和骨牌蕨属种类齐全、分布广泛,是这些属的分化和分布中心。(3)该地区蕨类植物生活类型齐全,以土生为主(占81.36%)。(4)恩施地区在中国蕨类植物地理区系中占有重要地位,该地区蕨类植物科属以泛热带区系成分相对较多,总体偏热带区系成分;物种以温带亚洲、东亚和中国特有分布型为主(占60.79%),具有显著的亚热带性质。(5)恩施蕨类植物区系与其他地区联系广泛,过渡性比较明显,尤其与四川地区联系紧密。     

中国蕨类植物孢子形态的研究ⅩⅣ.卷柏科

利用扫描电镜对中国产卷柏科25种植物孢子形态进行了观察。结果显示:(1)卷柏科植物大孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4;极面观一般为三角圆形或近圆形,赤道面观为近圆形、近扇形或近椭圆形;极轴长为158~548μm,赤道轴长为196~675μm。(2)小孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4或几达赤道线;极面观一般为近圆形或三角圆形,赤道面观为近圆形或近扇形;极轴长为10~40μm,赤道轴长为17~63μm。(3)孢子表面具颗粒状、瘤状、疣状、刺状、棒状、网状、片状、疣块状和脑状纹饰。研究认为,孢子形态特征可以作为该科亚属及种的分类学依据。     

23种顶蒴藓类孢子形态的观察

报道了中国２３种顶蒴藓类孢子的形态特征。观察结果显示：孢子形状有两类,球形和卵球形。孢子直径可分为４组：１０μm以下、１１－２０μm、２１－３０μm和３１μm以上。萌发孔有３种类型：近极薄壁区、单裂缝和无萌发孔。外壁纹饰有４种：棒状、瘤状、疣状和鼓槌状。孢子颜色有６种：黄褐色、黑褐色、金黄色、草绿色和紫红色。藓类孢子体积不同物种间有差异,但球形和卵球形是基本类型。苔藓孢子的萌发孔有３种类型：三裂缝为类     

A new late Westphalian fossil marattialean fern from Nova Scotia

Sydneia manleyi gen. et sp. nov. is based on part of a fertile frond from the upper Westphalian D of the Sydney Coalfield, Nova Scotia, Canada. It has small synangia composed of laterally fused sporangia that are elongate and with a circular cross-section. The sporangia yielded variably sized monolete and trilete spores with laevigate and microspinate ornamentation; intermediate forms were also observed. The spores can be correlated with the sporae dispersae species Latosporites minutus , Punctatosporites oculus and Laevigatosporites minimus . Size distribution of the spores is variable and highly skewed, suggesting heterogeneity of the spores within the sporangium. Spore ultrastructure indicates that the fossil is part of a fern, and the morphology of the spores and synangia indicate marattialean affinities.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 199–212.     

Some notes on Marattia anglica from the Jurassic of Yorkshire

In this paper the spores of the Jurassic fern Marattia anglica are redescribed. It appeared that at least 30% of the spores have a more or less trilete, instead of the usual monolete, laesura. In Marattia muensteri, M. hoerensis and M. crenulata (three species from the Jurassic), trilete spores also appeared to occur, although in much lower percentages than in M. anglica. The spores of M. anglica are compared with recent Marattia spores and with Jurassic dispersed spores.Furthermore, the systematic position of M. anglica and other Jurassic Marattia species is discussed.     

STUDIES OF PALEOZOIC MARATTIALEANS: NEW SPECIES OF SCOLECOPTERIS (MARATTIALES) FROM THE PENNSYLVANIAN OF NORTH AMERICA

Two new species of the late Paleozoic fern Scolecopteris (Marattiales) are described and their relationships within the genus are discussed. Scolecopteris charma sp.n., from Steubenville, Ohio (Duquesne Coal, Upper Pennsylvanian), is similar to species in the Oliveri group, while S. gnoma sp.n. from Providence, Kentucky (Baker Coal, Middle Pennsylvanian), compares favorably with the Latifolia species group. Scolecopteris gnoma is most similar to S. fragilis but differs in its smaller synangia and spore type. S. charma appears generally similar to S. iowensis because of its large pedicel and histologically undifferentiated walls, but differs in a number of characters such as vasculature and spore type. Despite its occurrence late in the Pennsylvanian, S. charma is thought to possess a number of primitive character states (large trilete spores, vascularized pedicels, flat pinnules with downturned margins). Using the same criteria for the much older S. gnoma, we note a number of relatively apomorphic character states (small monolete spores, unvascularized pedicels, extended pinnule margins). An outgroup analysis of species-level characters of Scolecopteris gives a better concept of primitive versus derived traits in marattialean and other ferns. Genera in the Paleozoic fern orders Filicales (Ankyropteris) and Zygopteridales (Corynepteris, Musatea) were chosen as outgroups, and the comparisons support suggestions for the polarity of several important characters. Some of these agree with previously proposed evolutionary polarities based on the geological occurrence of marattialean ferns.     

Studies in the Spore Morphology of Vittaria Smith

The spore morphology of 32 species of Vittaria Smith has been described. Spores are ellipsoidal or long ellipsoidal in polar view, and kidney-shaped in equatorial view, (18.2–65) × (39–110.5) × (19.5–52)μ in size, monolete, without perine. The stratification of exine which is generally 1.9–2.6 μ in thickness is distinct or indistinct. When it is distinct, the sexine is thicker than the nexine. The exine is generally orna- mented with indistinct granulose or vague sculpture, and with small verrucae in three species. In some species, there is a striate texture on the surface of the exine. As far as it goes, it is a very interesting phenomenon that has not been mentioned elsewhere in the literature of palynology. According to the references, the spores are trilete in a few species of this genus. But it is only monolete in our investigated meterial. Because the gross-morphology of plant in these genera of Vittariaceae is very similar to one anther, we raise the quastion whether the few species which have trilete spores really belong to this genus or to the other genus of Vittariaceae which have trilete, it may be further considered. On the basis of the spore types, Vittariaceae (E. B. Copeland, 1948) may be divided into two groups the one belongs to monolete spore type, and the other to trilete spore type. Based on morphology and anatomy of the plant, R. C. Ching (1940) separated out some genera which have trilete from Vittariaceae to establish a new family– Antrophyaceae, it is valuable to further exploration.     

Spore morphology of Serpocaulon A.R.Sm. and related taxa from Brazil (Polypodiaceae)

The epiphytic fern genus Serpocaulon (Polypodiaceae) comprises 42 species nested within the neotropical clade of the family together with genera such as Campyloneurum, Grammitis, Microgramma, Niphidium, Pleopeltis, Pecluma, Polypodium and Terpsichore. Although Serpocaulon is a well-supported genus, its intra-specific relationships are still not completely resolved. The morphological dataset for Serpocaulon and related genera is therefore expanded here with information on spore morphology to provide additional information for phylogenetic consideration. Spores have been collected from herbarium vouchers and acetolysed for light and scanning electron microscopy. All members of the neotropical clade have monolete spores, except for Grammitis and Terpsichore, which have trilete spores. Both verrucate and papillate ornamentation types are recognised. The palynological analysis shows close similarity between spores of Serpocaulon, Campyloneurum, Pleopeltis and Polypodium and supports close phylogenetic relationships between these taxa. Species of the grammitid clade, although nested within the Polypodiaceae, have spore morphology that supports a separate position.     

Ecological and evolutionary consequences of desiccation tolerance in tropical fern gametophytes

Ferns have radiated into the same diverse environments as spermatophytes, and have done so with an independent gametophyte that is not protected by the parent plant. The degree and extent of desiccation tolerance (DT) in the gametophytes of tropical fern species was assessed to understand mechanisms that have allowed ferns to radiate into a diversity of habitats. Species from several functional groups were subjected to a series of desiccation events, including varying degrees of intensity and multiple desiccation cycles. Measurements of chlorophyll fluorescence were used to assess recovery ability and compared with species ecology and gametophyte morphology. It is shown that vegetative DT (rare in vascular plants) is widely exhibited in fern gametophytes and the degree of tolerance is linked to species habitat preference. It is proposed that gametophyte morphology influences water-holding capacity, a novel mechanism that may help to explain how ferns have radiated into drought-prone habitats. Fern gametophytes have often been portrayed as extreme mesophytes with little tolerance for desiccation. The discovery of DT in gametophytes holds potential for improving our understanding of both the controls on fern species distribution and their evolution. It also advances a new system with which to study the evolution of DT in vascular plants.     

Organization of the vascular system in the stems of Diplazium and Blechnum (Filicales)

Detailed analysis of the three-dimensional vascular organization in species of Diplazium and Blechnum indicates that these ferns possess reticulate (dictyostelic) vascular systems that closely reflect the helical phyllotaxis of the shoot. In each species, the vascular pattern shows a specific relationship to the phyllotaxis, so that the phyllotactic fraction can be determined by examination of the number of cauline vascular bundles (meristeles) in cross section of the stem. The number of meristeles in a cross section equals the denominator of the phyllotactic fraction, i.e., the number of foliar orthostichies on the stem. The same numerical relationship also exists in the eusteles of seed plants between the number of axial (sympodial) stem bundles and the phyllotaxis. There is a further parallel between the three-dimensional reticulate pattern of fern dictyosteles and the reticulate patterns that characterize some herbaceous dicotyledons. However, the hypothesized separate origins of seed plant eusteles and fern dictyosteles from protostelic precursors preclude any direct homologies between these similar patterns. The parallel evolution of presumably more physiologically efficient reticulate systems in herbaceous seed plants and in ferns that have only a primary plant body is noteworthy. The similar relationships between the primary stem vascular patterns and phyllotaxy in both ferns and seed plants further emphasize the likely similarity of the morphogenetic events that occur at the shoot apex in these taxonomically disparate groups.     

Does lack of available suitable habitat explain the patchy distributions of rare calcicole fern species?

In Canada, as in many countries, a relatively large number of fern species occur in specialized habitats and have low numbers of known populations containing few individuals. It has been suggested that the distribution of ferns is mostly determined by factors of climate and habitat due to relatively low limitations in ferns for dispersal and establishment. Here, we attempt to explain whether the local patchy distribution of three calcicole fern species rare in Canada ( Asplenium ruta-muraria , Pellaea atropurpurea and Woodsia obtusa ) is due to a lack of available habitat. Analyses based on micro-scale differences between sites occupied by the ferns and nearby, unoccupied sites did not reveal any significant differences, thereby indicating that the rarity of these species is not entirely driven by the rarity of their microhabitat at a local scale. Our results suggest that the widely accepted premise that ferns are not limited by dispersal or establishment should be reconsidered, as such limitations are the only likely explanation for empty available and suitable habitat.     

Diversity and distribution of ferns in sub-Saharan Africa, Madagascar and some islands of the South Atlantic

Aim This paper reports the diversity and endemism patterns of African ferns, and explores the potential role of diversity refuges and environmental and historical factors in the shaping of these patterns. Material and locations The extant fern taxa occupying Africa south of the Sahara, Madagascar and some islands of the South Atlantic. Methods The number of taxa in each area or operational geographical unit (OGU) was scored, and the correlation between this number and physical and climatic variables analysed by standard pairwise and stepwise multiple regression analysis (SPR and SMR). The effects of biological factors such as dispersal capacity, reproductive biology, genetic features and certain physiological adaptations were evaluated by comparing the number of species in each OGU. Floral affinities among OGUs were analysed using non‐metric multi‐dimensional scaling (NMS) and parsimonic analysis of dispersion (PAD), and compared with β‐turnover and inter‐OGU distances. Results OGU area, elevation and the distance between refuges determined the composition of local floras, but only greater OGU area and the existence of higher maximum elevations increased species richness. The distance between refuges also affected the number of endemic species, especially on islands. The biological features studied only slightly influenced fern distribution. The main climatic predictor of species number was humidity. SPR and SMR revealed three main groups of ferns with different ecological trends. NMS and PAD analyses separated the four areas of highest diversity in Africa, three of which are inhabited by ferns with distinct ecological requirements. The fourth area was Madagascar, which shows an accumulation of endemic and relict diversity that is not easy to explain. Main conclusions The distribution of ferns in Africa has been influenced by refuges. These probably allowed many species to recolonize the neighbouring areas after the extinctions of the Pleistocene. Three major components were detected in the African flora: Guinea‐Congolian thermophilous, cold‐tolerant Afro‐montane, and Southern drought‐tolerant elements. These are related to the three main refuge areas, i.e. the Gulf of Guinea area, the eastern tropical region, and the Cape region. Endemicity in ferns was found to be lower than that of seed plants due to the higher dispersability of fern spores. The distance between OGUs seems to be the main predictor of the number of endemic fern species these areas contain.