New cultivated species of the genusCryptocoryne (Araceae)

Three new species ofCryptocoryne are described, based on material received from unspecified localities in tropical Asia.Crytocoryne hejnýi Rataj andC. zukalii Rataj differ fromC. cor data Griff. by the non-infundibuliform gorge of the upper tube and by the colour of the limb of spathe.C. evae Rataj is one of the largest species of the genus and is related toC. siemensis Gagn, andC. zonata De Wit. It differs fromC. siemensis andC. blasii by the limb of spathe which is twice as broad and long, and by the coloured inner part of the kettle, fromC. zonata by the shape of the leaf-blades.     

Presence of Rhapidosomes in Various Species of Bacteria and Their Morphological Characteristics

Rod-shaped structures have been observed in cells of Pseudomonas, Photobacterium, Proteus, and Saprospira by use of the negative-contrast stain. These structures, referred to as rhapidosomes, appear to be normal components of these cells. Other bacteria including Escherichia, Salmonella, Shigella, Klebsiella, Micrococcus, Bacillus, Mycobacterium, Rhodospirillum, and Hydrogenomonas genera failed to reveal these structures. The rhapidosomes of Saprospira were found to consist of two rods, one encasing a narrower, longer structure. In contrast, the rhapidosomes of Pseudomonas, Proteus, and Photobacterium were without the rigid inner structure, but were occasionally seen filled with a homogeneous material as observed by the negative stain. Ultrathin sections of Pseudomonas cells indicate that these rhapidosomes are embedded within or are in close association with the nucleoplasm.     

Ovules and seeds in Acalyphoideae (Euphorbiaceae): structure and systematic implications

Acalyphoideae, the largest subfamily of Euphorbiaceae, are investigated with respect to ovule and seed structure on the basis of 172 species of 80 genera in all 20 tribes of Acalyphoideae sensu Webster. All species of Acalyphoideae examined have bitegmic ovules with a non-vascularized inner integument. However, noticeable differences exist among and sometimes within the genera in the thickness of the inner and outer integument, the presence or absence of vascular bundles in the outer integument, whether ovules are pachychalazal or not, the presence or absence of an aril, seed coat structure (in terms of the best-developed mechanical cell-layer), and the shape of cells constituting the exotegmen. For the latter two characters, two different types of seed coat (i.e., "exotegmic" and "exotestal") and three different types of exotegmic cell (i.e., palisadal, tracheoidal and ribbon-like) were distinguished. Comparisons showed that three tribes Clutieae, Chaetocarpeae and Pereae are distinct from the other Acalyphoideae as well as from the other Euphorbiaceae in having an exotestal seed coat with a tracheoidal exotegmen. The tribe Dicoelieae is also distinct from the other Acalyphoideae in having an exotegmic seed that is composed of ribbon-like cells of exotegmen (i.e., cells both longitudinally and radially elongated, sclerotic and pitted). The tribe Galearieae, which should be treated as a distinct family Pandaceae, is also distinct from the other Acalyphoideae in having an exotegmic seed with a tracheoidal exotegmen (i.e., cells longitudinally elongated, sclerotic and pitted). The remaining genera of Acalyphoideae always have an exotegmic seed with a palisadal exotegmen (i.e., cells radially elongated, sclerotic and pitted). The shared palisadal exotegmen supports the close affinity of Acalyphoideae (excluding five tribes) with Crotonoideae and Euphorbioideae. Within the remaining genera of Acalyphoideae, a significant diversity is found in ovule and seed morphology with respect to the thickness of the inner and outer integument, the size of chalaza, vascularization of an outer integument and an aril.     

Classification,distribution and phylogeny of the genus Ottelia

The genus Ottelia is one of the great genera of Hydrocharidaceae. About 25 species distributed in the Palaeotropics, extending from Africa through India and SE. Asia to Korea and Japan, Australia and New Caledonia, 1 species in Brazil; centres of specific devolopment are found in Central Africa and SE Asia. The present study is mainly based on the materials collected during the field explorations in the lakes of Yunnan and observations on the structure of the spathe and flowers, the variation of leaf of the plants cultivated in Kunming Bot. Garden. Instead of the wings of the spathe used by Dandy, by the characters such as uni-or bisexual flowers, this genus is divided into two subgenera, which by the number of the flowers in spathe and the number of the carpus in ovary again subdivided into 4 sections. They are as the following: A. Subg. Ottelia. Flowers bisexual. Sect. 1. Ottelia. Spathe with 1 flower; ovary with 6(—9) carpus. Sect. 2. Oligolobos (Gagnep.) Dandy. Spathe with many flowers; ovary with 3 carpus. B. Subg. Boottia (Wall.) Dandy. Flowers unisexual; the male spathe with 1-many flowers, the female spathe with many flowers. Sect. 3. Boottia. The male spathe with 1 flower; ovary with 9(—15) carpus. Sect. 4. Xystrolobos (Gagnep.) H. Li. The female spathe with (2-) many flowers; ovary with 3 or 9 carpus. The Chinense species of ottelia is in great need for revision. All of the species in China previousely described under Ottelia Pers, Boottia Wall., Oligolobos Gagnep, and Xystrolobos Gagen. are here combined into 3 species. They are O. alismoides, O. cordata, O. acuminata with 4 variaties. After a study of the geographic distribution and infer relation-ships among the floristic elements it has been proved that Ottelia is certainly an ancient genus, and the primitive types came into being and widely dispersed before the separation of Laurasia from Gondwana. During a considerable period of time the elements of the genus Ottelia in freshwater environment of different continents have been separately differentiated and evolved into more or less derived types. The structure of flowers in all of the asian species shows the following evolutionary tendenoes: 1. In this genus the plants with unisexual flowers have evolved from plants with bisexual flower; 2. In the groups with bisexual or unisexual flowers the number of stamens and styles reduced to 3-merous, but the number of flowers in spathe increased. So that the subgenus Ottelia is more primitive than the subgenus Bottia; While in the subgenus Ottelia O. alismoides is a more primitive than O. balansae and in the subgenus Boottia O. cordata is the most primitive, butO. alata seems to be the most advanced.     

花背蟾蜍蝌蚪胃的发育形态学观察

应用大体解剖、组织切片和扫描电镜3种形态学方法对花背蟾蜍(Bufo raddei)蝌蚪在生长发育和变态过程中胃的形态结构变化进行了观察。结果显示,在蝌蚪发育24期(即G24)消化道呈简单的管状结构,胃与小肠等区分不明显,胃壁由内层矮柱状黏膜上皮细胞和其外的扁平上皮细胞层构成;直到26期胃略膨大,呈短粗管状,与小肠和食道可明显区分,胃壁内层的黏膜上皮细胞呈高柱状,上皮细胞间出现少量杯状细胞;36期的胃管明显膨大,其壁已具有胃的4层基本组织结构,杯状细胞数量增加,黏膜上皮细胞游离面有细长的微绒毛交织成网状覆盖;42期胃发育呈"C"字形,胃壁具备了消化道典型的4层结构,有胃腺芽出现,黏膜细胞的微绒毛短而直立,仅极少数细胞有长的微绒毛;蝌蚪发育到46期,肠道缩短,胃呈"J"字状,占消化道大部分,胃体中胃腺发达。在临近肝一侧,黏膜上皮细胞的微绒毛较短,胃腺少而小;而在相反一侧,微绒毛较长,胃腺多而大。基于上述结果说明,花背蟾蜍蝌蚪胃在36期已经基本完成了组织结构的分化,在变态发育期间结构和功能得到进一步完善,以适应变态后陆地生活的食性变化。     

Cytoskeletal cytoplasmic filament ribbon of Treponema: a member of an intermediate-like filament protein family

Development of genetic systems for many bacterial genera, including Treponema, now allow the study of structures that are specific to certain pathogens. The cytoplasmic filament ribbon of treponemes that is involved in the cell division cycle has a unique organization. Cytoplasmic bridging proteins connect the filaments, maintaining the distance between them and providing the overall ribbon-like structure. The filaments are anchored by proteins associated with the inner membrane. Each filament is composed of a unique monomer, the cytoplasmic filament protein A (CfpA), with coiled-coils secondary structures. CfpA is part of a growing family of proteins that we propose to call bacterial intermediate-like filaments (BILF).     

中国伞形科天胡荽亚科果实解剖特征及其系统学意义

经对中国伞形科天胡荽亚科 (Hydrocotyloideae)中天胡荽属 (HydrocotyleL .)积雪草属 (CentellaL .)和马蹄芹属(DickinsiaFranch .) 10种植物果实解剖结构的观察比较 ,发现 3属的果实横切面以合生面为基准可以分成 2个类型 ,即两侧压扁类型 (天胡荽属和积雪草属 )和背腹压扁类型 (马蹄芹属 )。除此之外 ,中果皮的外侧是否有色素块沉积、内侧是否有木化细胞层或厚壁细胞层以及最内层是否形成晶体细胞层 ,内果皮细胞的层数、排列方向以及有无棱槽油管等性状 ,可以作为区分 3属的重要解剖学特征。在此基础上 ,结合外部形态特征 ,讨论了该亚科及其内部各属的解剖学特征、属间区别及其演化关系。认为马蹄芹属应归属于Mulineae族 ,另外 2个属应归属于天胡荽族(Hydrocotyleae) ;3属中积雪草属原始而马蹄芹属进化 ;天胡荽亚科可能不是自然的类群 ,它的分类系统和演化地位有待深入研究。     

Integrated small RNA profiling and degradome analysis of Anthurium andraeanum cultivars with different-colored spathes

MicroRNAs (miRNAs) are known to play vital roles in coloration of leaves, flowers, and fruits in plants. However, their functions in spathe coloration are poorly known. Anthurium andraeanum is a popular ornamental plant with various spathe colors. In this study, small RNA and degradome libraries from three A. andraeanum cultivars with different-colored spathes were constructed and sequenced. Illumina sequencing resulted in 94 conserved miRNAs, and 34 novel miRNAs in total were then identified based on precursor sequences and hairpin structures. Differential expression analysis showed that 52, 51, and 49 miRNAs were differentially expressed in comparisons of orange- versus white-colored spathe, purple- versus white-colored spathe, and purple- versus orange-colored spathe, respectively. The expression patterns of miRNAs and their corresponding targets involved in spathe coloration were further analyzed, and displayed that miR156b and miR529 were highly abundant in the spathes with higher anthocyanin content. These two miRNAs co-targeted a gene encoding SPL17, which may function as a negative regulator in anthocyanin accumulation. In addition, miR408 was also abundantly expressed in purple- and orange-colored spathes, and its typical targets were also identified. This comprehensive integrated analysis provides insight into the miRNA-mediated genetic regulation in spathe coloration of A. andraeanum.

     

Architecture and assembly of the Type VI secretion system

The Type VI secretion system (T6SS) delivers protein effectors to diverse cell types including prokaryotic and eukaryotic cells, therefore it participates in inter-bacterial competition and pathogenesis. The T6SS is constituted of an envelope-spanning complex anchoring a cytoplasmic tubular edifice. This tubular structure is evolutionarily, functionally and structurally related to the tail of contractile phages. It is composed of an inner tube tipped by a spike complex, and engulfed within a sheath-like structure. This structure assembles onto a platform called “baseplate” that is connected to the membrane sub-complex. The T6SS functions as a nano-crossbow: upon contraction of the sheath, the inner tube is propelled towards the target cell, allowing effector delivery. This review focuses on the architecture and biogenesis of this fascinating secretion machine, highlighting recent advances regarding the assembly of the membrane or tail complexes. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.     

Recombinant expression of tatABC and tatAC results in the formation of interacting cytoplasmic TatA tubes in Escherichia coli

The twin-arginine translocation (Tat) system of bacteria and plant plastids serves to translocate folded proteins across energized biological membranes. In Escherichia coli, the three components TatA, TatB, and TatC mediate this membrane passage. Here we demonstrate that TatA can assemble to form clusters of tube-like structures in vivo. While the presence of TatC is essential for their formation, TatB is not required. The TatA tubes have uniform outer and inner diameters of about 11.5 nm and 6.7 nm, respectively. They align to form a crystalline-like structure in which each tube is surrounded by six TatA tubes. The tube structures become easily detectable even at only a 15-fold overexpression of the tatABC genes. The TatA tubes could also be visualized by fluorescence when untagged TatA was mixed with low amounts of TatA-GFP. The structures were often found in contact with the cell poles. Because TatC is most likely polar in E. coli, as demonstrated by a RR-dependent targeting of translocation-incompatible Tat substrates to the cell poles, and because TatC is required for the formation of aligned TatA tubes, it is proposed that the TatA tubes are initiated at polarly localized TatC.     

Electron Microscopic Observations on the Structure of the Envelopes of Mature Elementary Bodies and Developmental Reticulate Forms of Chlamydia psittaci

Purified suspensions of Chlamydia psittaci were prepared from L cells. Thin sections of intact elementary bodies and intact developmental reticulate bodies and of their purified envelopes were observed by electron microscopy. In both intact organisms and partially purified envelopes, two membranous structures, each appearing in electron micrographs as two darkly stained layers, were observed. In the elementary body sections, the outer membrane was round, apparently rigid, and was not soluble in 0.5% sodium dodecyl sulfate. The inner layer was irregular in shape and was completely removed by detergent treatment. We interpret these results to indicate that the outer rigid layer of the envelope is the cell wall and the inner layer is the cytoplasmic membrane. When the fragile reticulate body envelopes were similarly studied, the outer cell wall was clearly visible, and some evidence of an inner membrane was seen. After treatment with nucleases and detergent, all evidence of inner or cytoplasmic membrane was removed, but the outer cell wall remained. Thus, it appears that the cell wall of this organism is continuous throughout the growth cycle and that the fragility and lack of rigidity of the reticulate body cell is due to changes in chemical composition or structure of the cell wall.     

Further observations on the ultrastructure of Cystosporogenes operophterae (Canning, 1960) (phylum Microsporidia) parasitic in Operophtera brumata L. (Lepidoptera, Geometridae)

Reinvestigation of Cystosporogenes operophterae [J. Parasitol. 46 (1960) 755] by electron microscopy confirmed that development in host cells takes place in a vacuole with a single membrane at its boundary. Although ribosomes were not clustered on this membrane, it is hypothesised that it originates from host endoplasmic reticulum. The dome-shaped anchoring disc, the morphology of the polaroplast and the separation of the polar tube coils from the ribosome-packed cytoplasm are newly described details of spore structure. The polaroplast consists of an outer region of compact lamellae forming 'arms' surrounding an inner region of widely spaced lamellae. The 'arms' extends back into the region of an elongate nucleus. The genera Cystosporogenes and Endoreticulatus were differentiated by their positions in a previously obtained 16S rDNA phylogeny and on the new ultrastructural data.     

Studies of male sexual tubes in hermit crabs (crustacea, decapoda, anomura, paguroidea). I. Morphology of the sexual tube in Micropagurus acantholepis (Stimpson, 1858), with comments on function and evolution

The external morphology and internal structure of the male sexual tube of the hermit crab Micropagurus acantholepis, a member of the family Paguridae from Australian waters, is described in detail using histological thick sectioning and scanning and transmission electron microscopy techniques. This is the first in-depth study of a sexual tube in the Paguroidea, a group where a remarkable number of genera (55.9% in the family Paguridae) with species having these intriguing sexual structures are known. In M. acantholepis a sexual tube is present on the left side, whereas only a gonopore is present on the right side. The tube is used for the delivery of spermatophores to the female and consists of a sheath of cuticular origin surrounding an internal, functional extension of the posterior vas deferens. Pedunculate spermatophores were observed within the lumen and partially extruding from the terminal opening of the tube in preserved specimens. The tube protrudes from the left coxa of the fifth pereopod as an elongate 3-mm-long, hollow, coiled structure with a terminal opening. Exteriorly the tube consists of a conspicuous thick chitinous cuticular ridge throughout its length, and a thin chitinous cuticle with sparse, regularly arranged simple setae. Interior to the cuticle, the tube contains loose connective tissue, secretory cells, oblique muscle, circular muscle, and epithelial cells. The latter cells line a central lumen that runs the length of the sexual tube. The morphology, cellular composition, and function of the tube are discussed.     

Structure of spermatodoses in shield-back bushcrickets (Tettigoniidae,Tettigoniinae)

Many aspects of the reproductive anatomy and physiology of tettigoniids have been studied extensively. These include the large, externally visible spermatophores and the bundles of sperm, known as spermatodesms. However, spermatodoses, spermatophore-like structures found within the spermatheca, seem to have been almost completely overlooked: their structure has not been described since 1913 and they have subsequently received only passing mention in the literature. Each time the female mates, a separate spermatodose is formed. Here I use photographs, from light-microscopy, of whole and sectioned spermatodoses to describe the external and internal structure of spermatodoses of nine different genera within the subfamily Tettigoniinae. The structure of the spermatodoses is very similar for the different genera. Each spermatodose is pear- or onion-shaped and consists of a thin outer layer, enclosing a thick, gelatinous inner layer. A large sperm mass occupies the bulbous end of the spermatodose, while a thin sperm-tube leads from the sperm mass, along the center of the elongated neck of the spermatodose, and appears to exit at the pointed-tip of the spermatodose. Feather-like bundles of sperm (spermatodesms) were clearly visible within the sperm mass and also appeared to be present within the sperm-tube. The wall of the sperm tube appeared to be composed of material similar to that of the outer layer of the spermatodose. Within the spermatheca, spermatodoses appeared to be stratified in that only one of them ever occupied the position nearest to the spermathecal duct. The possible function of spermatodoses is discussed: it is proposed that they have evolved as a result of sexual conflict and function to protect the sperm from being destroyed by the female while they are in storage.     

Tube formation by complex cellular processes in Ciona intestinalis notochord

In the course of embryogenesis multicellular structures and organs are assembled from constituent cells. One structural component common to many organs is the tube, which consists most simply of a luminal space surrounded by a single layer of epithelial cells. The notochord of ascidian Ciona forms a tube consisting of only 40 cells, and serves as a hydrostatic “skeleton” essential for swimming. While the early processes of convergent extension in ascidian notochord development have been extensively studied, the later phases of development, which include lumen formation, have not been well characterized. Here we used molecular markers and confocal imaging to describe tubulogenesis in the developing Ciona notochord. We found that during tubulogenesis each notochord cell established de novo apical domains, and underwent a mesenchymal–epithelial transition to become an unusual epithelial cell with two opposing apical domains. Concomitantly, extracellular luminal matrix was produced and deposited between notochord cells. Subsequently, each notochord cell simultaneously executed two types of crawling movements bi-directionally along the anterior/posterior axis on the inner surface of notochordal sheath. Lamellipodia-like protrusions resulted in cell lengthening along the anterior/posterior axis, while the retraction of trailing edges of the same cell led to the merging of the two apical domains. As a result, the notochord cells acquired endothelial-like shape and formed the wall of the central lumen. Inhibition of actin polymerization prevented the cell movement and tube formation. Ciona notochord tube formation utilized an assortment of common and fundamental cellular processes including cell shape change, apical membrane biogenesis, cell/cell adhesion remodeling, dynamic cell crawling, and lumen matrix secretion.     

Ultrastructure of a possible new type of crustacean cuticular strain receptor in Carcinus maenas (crustacea,decapoda)

A hitherto unknown sensillum type, the “intracuticular sensillum” was identified on the dactyls of the walking legs of the shore crab, Carcinus maenas. Each sensillum is innervated by two sensory cells with dendrites of “scolopidial” (type I) organization. The ciliary segment of the dendrite is 5–6 μm long and contains A-tubules with an electron-dense core and dynein arm-like protuberances; the terminal segment is characterized by densely packed microtubules. The outer dendritic segments pass through the endo- and exocuticle enclosed in a dendritic sheath and a cuticulax tube (canal), which is suspended inside a slit-shaped cavity by cuticular lamellae. The dendrites and the cavity terminate in a cupola-shaped invagination of the epicuticle. External cuticular structures are lacking. Three inner and four to six outer enveloping cells are associated with each intracuticular sensillum. The innermost enveloping cell contains a large scolopale that is connected to the ciliary rootlets inside the inner dendritic segments by desmosomes. Scolopale rods are present in enveloping cell 2. Since type I dendrites and a scolopale are regarded as modality-specific structures of mechanoreceptors, and since no supracuticular endorgan is present, the intracuticular sensilla likely are sensitive to cuticular strains. The intracuticular sensilla should be regarded as analogous to insect campaniform sensilla and arachnid slit sense organs.     

A new class and order of myxozoans to accommodate parasites of bryozoans with ultrastructural observations on Tetracapsula bryosalmonae (PKX organism)

Tetracapsula bryosalmonae, formerly PKX organism, is a myxozoan parasite that causes proliferative kidney disease in salmonid fish. Its primary hosts, in which it undergoes a sexual phase, are phylactolaemate bryozoans. It develops in the bryozoan coelomic cavity as freely floating sacs which contain two types of cells, stellate cells and sporoplasmogenic cells, which become organised as spores. Eight stellate cells differentiate as four capsulogenic cells and four valve cells which surround a single sporoplasmogenic cell. The sporoplasmogenic cell undergoes meiosis and cytoplasmic fission to produce two sporoplasms with haploid nuclei. Sporoplasms contain secondary cells. The unusual development supports previously obtained data from 18S rDNA sequences, indicating that species of Tetracapsula form a clade. It diverged early in the evolution of the Myxozoa, before the radiation that gave rise to the better known genera belonging to the two orders in the single class Myxosporea. The genus Tetracapsula as seen in bryozoans shares some of the characters unique to the myxosporean phase and others typical of the actinosporean phase of genera belonging to the class Myxosporea. However, it exhibits other features which are not found in either phase. A new class Malacosporea and order Malacovalvulida are proposed to accommodate the family Saccosporidae and genus Tetracapsula. Special features of the new class are the sac-like proliferative body, valve cells not covering the exit point of the polar filament, lack of a stopper-like structure sealing the exit, maintenance of valve cell integrity even at spore maturity, absence of hardened spore walls and unique structure of sporoplasmosomes in the sporoplasms.     

A one‐step rectification of sperm cell targeting ensures the success of double fertilization

Successful fertilization in animals depends on competition among millions of sperm cells, whereas double fertilization in flowering plants usually involves just one pollen tube releasing two immobile sperm cells. It is largely a mystery how the plant sperm cells fuse efficiently with their female targets within an embryo sac. We show that the initial positioning of sperm cells upon discharge from the pollen tube is usually inopportune for gamete fusions and that adjustment of sperm cell targeting occurs through release and re-adhesion of one sperm cell, while the other connected sperm cell remains in stagnation.This enables proper adhesion of each sperm cell to a female gamete and coordinates the gamete fusions. Our findings reveal inner embryo sac dynamics that ensure the reproductive success of flowering plants and suggest a requirement for sperm cell differentiation as the basis of double fertilization.     

Ultrastructure of the labrum and foregut of Derocheilocaris remanei (Crustacea,Mystacocarida)

The cuticle-lined foregut of Derocheilocaris remanei consists of the mouth with its associated labrum, and an undifferentiated esophagus. It is separated from the midgut by an esophageal valve. The labrum is a conspicuous structure moved by five pairs of muscles (four dorsoventral and one longitudinal). Four pairs of subcuticular glands open to its inner face forming two longitudinal, lateral rows of cuticular pores. Each secretory unit is composed of a glandular component (with one or two secretory cells), a neck cell, and a duct cell. In addition, a single gland cell opens mesially into the buccal cavity. The ventrally located mouth is a complex structure characterized by a filter-like system, a sensory organ, and epithelial cells with highly developed microvilli. The esophagus is a simple tube with a characteristic curvature following the mouth. It has a rounded cross section and a triradiate lumen. A layer of circular musculature surrounds this region. The end of the esophagus protrudes into the midgut lumen forming the so-called esophageal valve. The ultrastructural features of the foregut, with the presence of a mucus-trapping mechanism, a relatively well-developed filter system and associated structures and an esophagus lacking glands confirm the microphagic feeding habits of mystacocarids. © 1996 Wiley-Liss, Inc.     

Environmental filtering predicts plant‐community trait distribution and diversity: Kettle holes as models of meta‐community systems

• Meta‐communities of habitat islands may be essential to maintain biodiversity in anthropogenic landscapes allowing rescue effects in local habitat patches. To understand the species‐assembly mechanisms and dynamics of such ecosystems, it is important to test how local plant‐community diversity and composition is affected by spatial isolation and hence by dispersal limitation and local environmental conditions acting as filters for local species sorting.We used a system of 46 small wetlands (kettle holes)—natural small‐scale freshwater habitats rarely considered in nature conservation policies—embedded in an intensively managed agricultural matrix in northern Germany. We compared two types of kettle holes with distinct topographies (flat‐sloped, ephemeral, frequently plowed kettle holes vs. steep‐sloped, more permanent ones) and determined 254 vascular plant species within these ecosystems, as well as plant functional traits and nearest neighbor distances to other kettle holes.Differences in alpha and beta diversity between steep permanent compared with ephemeral flat kettle holes were mainly explained by species sorting and niche processes and mass effect processes in ephemeral flat kettle holes. The plant‐community composition as well as the community trait distribution in terms of life span, breeding system, dispersal ability, and longevity of seed banks significantly differed between the two habitat types. Flat ephemeral kettle holes held a higher percentage of non‐perennial plants with a more persistent seed bank, less obligate outbreeders and more species with seed dispersal abilities via animal vectors compared with steep‐sloped, more permanent kettle holes that had a higher percentage of wind‐dispersed species. In the flat kettle holes, plant‐species richness was negatively correlated with the degree of isolation, whereas no such pattern was found for the permanent kettle holes.Synthesis: Environment acts as filter shaping plant diversity (alpha and beta) and plant‐community trait distribution between steep permanent compared with ephemeral flat kettle holes supporting species sorting and niche mechanisms as expected, but we identified a mass effect in ephemeral kettle holes only. Flat ephemeral kettle holes can be regarded as meta‐ecosystems that strongly depend on seed dispersal and recruitment from a seed bank, whereas neighboring permanent kettle holes have a more stable local species diversity.