A systematic investigation of leaf epidermis in <Emphasis Type="Italic">Camellia</Emphasis> using light microscopy

The characters of mature leaf epidermis of 58 species and 3 varieties belonging to 19 sections, representing all the 4 subgenera: Protocamellia, Camellia, Thea and Metacamellia were investigated under light microscope. The main conclusions are as follows: 1) The shape of the epidermal cells is elliptical, polygonal or irregular and the anticlinal walls are arched, straight or sinuolate, sinuous to sinuate. 2) The stomatal apparatus, consisting of a stoma (a pore plus a pair of guard cells) and 3–4 subsidiary cells, restricted to the abaxial surface of the leaves, were assigned to anisocytic, anisotricytic, isotricytic or tetracytic type. 3) Special structures in leaf epidermis, such as stomatal clusters, aborted stomata, secretory cells, cuticular intrusions and their taxonomic implications were also elucidated.     

安徽黄精属(Polygonatum)植物叶表皮研究

利用光学显微镜及扫描电子显微镜观察了安徽省黄精属９种植物的叶表皮;统计并测量了气孔类型、气孔大小、气孔密度及气孔指数等;描述了表皮角质膜、蜡质纹饰、气孔的形状及气孔外拱盖等有关特征。结果表明：黄精属植物叶表皮气孔器类型属只有２个保卫细胞而无任何副卫细胞的单子叶植物气孔器类型。气孔的某些特征,如气孔器类型、气孔器分布特征、表皮细胞形状及垂周壁式样、角质层及蜡质纹饰等在种间差异不大,可作种间区别的次级特征用。     

Epidermal Features of Leaves and Their Taxonomic Significance in Subfamily Ophiopogonoideae (Liliaceae)

This paper reports epidermal features of leaves in Ophiopogonoideae. Thirty-nine species and one variety (29 species, 1 variety in Ophiopogon, 6 species in Liriope, 4 species in Peliosanthes)were examined under scanning electron microscope. In addition, transections of stomatal apparatuses of six species (Ophiopogon: 3 species; Liriope: 2 species; Peliosanthes: 1 species) were made and examined under light microscope. The stomatal apparatus in Liriope, Ophiopogon and Peliosanthes is of the anomocytic type. These types of epidermal features of leaves in these genera are recognized: Cuticular processes type, No cuticular processes type and No stomatal band type. The cuticular processes type can be further divided into three patterns: Fibrillose, Massive and Wrinkled-massive. The taxonomic value of the epidermal features of leaves in Ophiopogonoideae is rather evident. (1)These epidermal features can be used to distinguish among those species of Ophiopogon, Liriope and Peliosanthes, even in their vegetative state; (2) The different patterns of cuticular processes are helpful to reasonable classification of some species in Ophiopogon, (3)They are of great value for recognizing some sections, (4) These epidermal features of leaves also provide evidence for further discussion on relationships among Ophiopogon, Liriope, and Peliosanthes. The evolutionary trend of the epidermal features of leaves in Ophiopogonoideae is No stomatal band type→No cuticular process type(stomatal band)→Cuticular process type (stomatal band). According to the epidermal features of leaves, flowers and fruits, Ophiopogon, Liriope and Peliosanthes are closely related, forming a subfamily Ophiopogonoideae. Ophiopogon is more close to Liriope than to Peliosanthes, and they should be grouped into the same tribe-Ophiopogoneae. Liriope seems to be more primitive than Ophiopogon. Peliosanthes, which constitutes another tribe of its ownPeliosantheae, is more advanced than Ophiopogon and Liriope, and it might have beenderived from its ancestor early.     

应用叶表皮结构讨论槽稃草属Euthryptochloa Cope(Gramineae)的归属问题

比较研究单种属,槽稃草属Euthryptochloa Cope与显子草属Phaenosperma Munro的叶表皮微形态,并结合外部形态特征说明槽稃草属与显子草属无论在叶表皮微形态或外部形态上都无区别。根据国际植物命名法规的优先律,槽稃草属不能独立成属,应归入显子草属。     

Studies on the Epidermal Structure of Tingia carbonica

Two leafy specimens of Tingia carbonica were collected as impression from Shanxi formation of Permian, from Inner Mongolia, China. The epidermal structure of its leaves is reported in this paper. Under SEM, well preserved epidermal cells as well as some concaves on the surface of large leaves were clearly recognized. The epidermal cells are approximately rectangular in shape, about 100～150 um long and 20～30 um wide. They are arranged longitudinally parallel to veins. The concaves usually in rows are round or elliptical, about 0.65～0.35 mm long and 0.2～0.35 mm wide. Density of concaves is about 1.8/ mm² and no stomata occur inside the concaves. In all probability, this is the upper epidermis. On the other side of the epidermis, anomocytic stomata are scattered irregularly, each with 5～6 epidermal cells around. The stomatal apertures are about 35.8 µm long, and 18.7 um wide, which is organised parallel to the common epidermal cells. As far as shape and size is concerned, it is similar to that described on the upper epidermis. Density of the stomata is about 60/mm². In all Probability, this is the lower epidermis. The ecological preference and classification of Tingia are discussed according to these new characters of the epidermis andsubordinate struture of the leaf.     

SEM study of surface structures of the spathe in Cryptocoryne and Lagenandra (Araceae: Aroideae: Cryptocoryneae)

SEM studies of the spathe structures in the two closely related genera Cryptocoryne and Lagenandra show differences between the inner and outer surfaces, as well as in cell structures in the various parts of the spathe. The cell structure reveals patterns mat makes it possible to depict homologous structures of the spathe, even though the spathes of the two genera look different. The basal part of the kettle has a mucilage covering of the cells, interpreted as a hitherto unnoticed food source. The cells of the inner surface of the kettle and tube have downward pointing trichomes. On the second day of flowering these collapse and sink into the cell lumen, which is suggested to create a unique lattice-like structure that enables the insects to climb out of the kettle and tube. The cell structure of the flap shows that it is a prolongation and continuation of the spathe tube margin.     

Cellular Differentiation and Leaf Morphogenesis in Arabdopsis

A focused approach that exploits a single plant species, namely, Arabidopsis thaliana, as a means to understand how leaf cells differentiate and the factors that govern overall leaf morphogenesis has begun to generate a significant body of knowledge in this model plant. Although many studies have concentrated on specific cell types and factors that control their differentiation, some degree of consensus is starting to be reached. However, an understanding of specific mechanisms by which cells differentiate in relation to their position, that appears to be an overriding factor in this process, is not yet in place for cell types in the Arabidopsis leaf. It is clear that perturbations in cellular development within the leaf do not necessarily have a general effect on morphogenesis. Environmental factors, particularly light, have been known to affect leaf cell differentiation and expansion, and endogenous hormones also appear to play an important role, through mechanisms that are beginning to be uncovered. It is likely that continued identification of genes involved in leaf development and their regulation in relation to positional information or other cues will lead to a clearer understanding of the control of differentiation and morphogenesis in the Arabidopsis leaf.     

Ultrastructural contributions to an understanding of the cellular mechanisms involved in lizard skin shedding with comments on the function and evolution of a unique Lepidosaurian phenomenon

Previous reports on the fine structure of lizard epidermis are confirmed and extended by SEM and TEM observations of cell differentiation and the form of shed material from the American anole Anolis carolinensis. Attention is drawn to two issues: 1) the tips of the spinules arising from the mature oberhautchen are markedly curved; this morphology can be seen during differentiation; 2) the median keels of scales from all parts of the body show “naked” oberhautchen cells that lack characteristic spinules, but have a membrane morphology comprising a complex system of serpentine microridges. Maderson's ([1966] J. Morphol. 119:39–50) “zip-fastener” model for the role of the shedding complex formed by the clear layer and oberhautchen is reviewed and extended in the light of recent SEM data. Apparently periodic lepidosaurian sloughing permits somatic growth; understanding how the phenomenon is brought about requires integration of data from the organismic to the molecular level. The diverse forms of integumentary microornamentation (MO) reported in the literature can be understood by considering how the cellular events occurring during the renewal phase prior to shedding relate to the emergence of the form-function complex of the β-layer, which provides physical protection. Issues concerning the evolutionary origin of lepidosaurian skin-shedding are discussed. J. Morphol. 236:1–24, 1998. © 1998 Wiley-Liss, Inc.     

Epidermal differentiation in the developing scales of embryos of the Australian scincid lizard Lampropholis guichenoti

Formation of the first epidermal layers in the embryonic scales of the lizard Lampropholis guichenoti was studied by optical and electron microscopy. Morphogenesis of embryonic scales is similar to the general process in lizards, with well‐developed overlapping scales being differentiated before hatching. The narrow outer peridermis is torn and partially lost during scale morphogenesis. A second layer, probably homologous to the inner peridermis of other lizard species, but specialized to produce lipid‐like material, develops beneath the outer peridermis. Two or three lipogenic layers of this type develop in the forming outer surface of scales near to the hinge region. These layers form a structure here termed “sebaceous‐like secretory cells.” These cells secrete lipid‐like material into the interscale space so that the whole epidermis is eventually coated with it. This lipid‐like material may help to reduce friction and to reduce accumulation of dirt between adjacent extremely overlapping scales. At the end of their differentiation, the modified inner periderm turns into extremely thin cornified cells. The layer beneath the inner peridermis is granulated due to the accumulation of keratohyalin‐like granules, and forms a shedding complex with the oberhautchen, which develops beneath. Typically tilted spinulae of the oberhautchen are formed by the aggregation of tonofilaments into characteristically pointed cytoplasmic outgrowths. Initially, there is little accumulation of β‐keratin packets in these cells. During differentiation, the oberhautchen layer merges with cells of the β‐keratin layer produced underneath, so that a typical syncytial β‐keratin layer is eventually formed before hatching. Between one‐fourth distal and the scale tip, the dermis under epidermal cells is scarce or absent so that the mature scale tip is made of a solid rod of β‐keratinized cells. At the time of hatching, differentiation of a mesos layer is well advanced, and the epidermal histology of scales corresponds to Stage 5 of an adult shedding cycle. The present study confirms that the embryonic sequence of epidermal stratification observed in other species is basically maintained in L. guichenoti. J. Morphol. 241:139–152, 1999. © 1999 Wiley‐Liss, Inc.     

Formation of large micro‐ornamentations in developing scales of agamine lizards

The embryonic scales of two Australian agamine lizards (Hypsilurus spinipes and Physignatus lesueuerii) derive from the undulation of the epidermis to form dome‐shaped scale anlage that later become asymmetric and produce keratinized layers. Glycogen is contained in basal and suprabasal cells of the forming outer scale surface that are destined to differentiate into β‐keratin cells. The outer peridermis is very flat, but the second epidermal layer, provisionally identified as an inner peridermis, is composed of large cells that accumulate vesicular bodies and a network of coarse filaments. The sequence of epidermal layers produced beneath the inner peridermis in these agamine lizards corresponds to that of previously studied lizards, but the first subperidermal layer has characteristics of both clear (keratohyalin‐like granules) and oberhautchen (dark β‐keratin packets) cells. This layer is here identified as an oberhautchen since it fuses with the underlying β‐keratinizing cells forming large spinulae as the entire tissue becomes syncytial so that the units appear to increase in size. These spinulae very likely represent sections of honeycomb‐shaped micro‐ornamentations. A mesos layer appears underneath the β‐layer before hatching. J. Morphol. 240:251–266, 1999. © 1999 Wiley‐Liss, Inc.