Epidermal Structure and Stomatal Ontogeny in Some Polygonales and Centrospermae

The epidermal structure and ontogeny of stomata in 19 speciesof Centrospermae and two of Polygonales are described. The cellsof the epidermis are polygonal, isodiametric, or elongated invarious directions and arranged irregularly. The anticlinalepidermal walls are thick, sinuous, straight, or arched. Eleventypes of glandular and eglandular trichomes have been observed.Six types of stomata: anomocytic, paracytic, stomata with asingle subsidiary cell, diacytic, anisocytic, and transitionalbetween diacytic and paracytic, have been noticed in the speciesinvestigated. The ontogeny of anomocytic stomata is haplocheilicor perigenous, while that of the other five types is syndetocheilicor mesogenous. Abnormal stomata with a single guard cell, unequalguard cells, aborted guard cells, and arrested development arecommon. Groups of stomata are also frequent but contiguous stomataare rather rare.     

Variation in the structure and development of foliar stomata in the Euphorbiaceae

The structure and ontogeny of foliar stomata were studied in 50 species of 28 genera belonging to 17 tribes of the family Euphorbiaceae. The epidermal cells are either polygonal, trapezoidal, or variously elongated in different directions and diffusely arranged. The epidermal anticlinal walls are either straight, arched or sinuous. The architecture of cuticular striations varies with species. The mature stomata are paracytic (most common), anisocytic, anomocytic and diacytic. Occasionally a stoma may be tetracytic, cyclocytic or with a single subsidiary cell. The ontogeny of paracytic stomata is mesogenous dolabrate or trilabrate, mesoperigenous dolabrate; that of diacytic stomata is mesogenous dolabrate, whereas that of anisocytic stomata is mesogenous trilabrate; rarely an anisocytic stoma may be mesoperigenous. Hemiparacytic stomata are mesoperigenous unilabrate; tetracytic stomata are mesoperigenous dolabrate and anomocytic stomata perigenous. Abnormalities encountered include four types of contiguous stomata, stomata with a single or both guard cells aborted and persistent stomatal initials. Cytoplasmic connections between the guard cells of two adjacent stomata or the guard cell of a stoma and an adjacent epidermal/subsidiary cell, or both types occurring in a species, were noticed. The stomatal development, distribution, diversity and basic stomatal type with reference to systematics are discussed.     

Structure and Ontogeny of Stomata in Some Polemoniales

The ontogeny and structure of stomata in 22 genera and 51 speciesof the Polemoniales are described. Five main types of stomatanoticed are: anisocytic, anomocytic, diacytic, paracytic, andstomata with a single subsidiary cell. Three modes of stomataldevelopment: syndetocheilic or mesogenous, haplocheilic or perigenous,and meso-perigenous or syndeto-haplocheilic are observed. Abnormalitiesseen are: stomata with single guard cells, arrested developmentand contiguous stomata variously oriented. Contiguous stomataresult from adjacently placed meristemoids or readjustment duringmaturation. Stomata with a single guard cell are formed as aresult of degeneration of one of the guard cells before or afterpore formation. The stomatal apparatus varies in different organsof a plant in form, number, orientation and arrangement of thesubsidiary and also the surrounding cells. Three lines leadingto Polemoniales, Boraginales, and Solanales are distinet.     

Epidermal Structure and Ontogeny of Stomata in some Verbenaceae

The present paper deals with epidermal structure and developmentof stomata in 14 species of Verbenaceae. The epidermal cellsare either polygonal, isodia-metric, or elongated in variousdirections, and irregularly arranged. The anticlinal walls arethick, mostly sinuous, occasionally arched or straight. Thesurface of the cuticle shows parallel, rarely corrugated, striations.Some 12 types of eglandular and glandular trichomes, and foliarnectaries are noticed. The mature stomata are diacytic, anisocytic,paracytic, with a single subsidiary cell, anomocytic and perigenous.The development of anomocytic stomata is perigenous, while thatof others is mesogenous or syndetocheilic type. Abnormalitiesnoticed here include contiguous stomata, stomata with a singleguard cell, and aborted guard cells.     

Structure and Development of Stomata in Some Leptosporangiate Ferns

The structure and development of stomata are described for 17species of leptosporangiate ferns. In these species the maturestomata are anomocytic, diacytic, Pyrrosia(applied), tetracytic,suspended, or floating type. Stomata are present on both surfacesof floating as well as sub merged leaves of Azolla and Marsilea.In a few species twin stomata, arrested development, and persistentstomatal initials are present Floating stomata result from disintegrationof the anticlinal suspending wall in Pleopeltis, and by detachmentand displacement in Azolla pinnata. The development of stomatais haplocheilic, syndetocheilic, or syndetohaplocheilic. InCyathea spinulosa the guard cell nuclei divide amitoticallyand the resulting two daughter nuclei occupy the opposite polesof the guard cells     

Structure, distribution and taxonomic importance of foliar stomata in some Indian Amaranthaceae

The structure, distribution and taxonomic importance of foliar stomata in 45 taxa belonging to 19 genera have been studied. In all, six stomatal types have been recognized viz., anomocytic, anisocytic, diacytic, paracytic, hemiparacytic and brachyparacytic. The majority of the taxa are amphistomatic whereas hypostomatic leaves are confined to only three taxa. Stomatal diversity is common but most of the taxa show either dominance or codominance. Stomatal distribution is helpful in distinguishing the three tribes of the Amaranthaceae. The tribe Celosieae shows exclusive presence of anomocytic and anisocytic stomata whereas Amarantheae and Gomphreneae show other stomatal types viz., paracytic and diacytic in addition to anomocytic and anisocytic stomata. Further, the latter two tribes are each distinguishable into two subtribes on the basis of stomata.     

Cuticular studies in some species of Mendoncia and Thunbergia (Acanthaceae)

The cuticular and epidermal anatomy of two species of Mendoncia (subfamily Mendoncioideae) and eight of Thunbergia (subfamily Thunbergioideae) has been studied. The species of Mendoncia are characterized by the presence of diacytic stomata on hypostomatic leaves, subsessile glandular hairs with a globular head, non-glandular hairs with a stellate hair-base, and the absence of cystoliths. In Thunbergia the cuticles show diacytic stomata on hypostomatic leaves, subsessile glandular hairs with a panduriform head, and non-glandular hairs with a two- or more-celled simple hair-base. Cystoliths are absent. The presence of diacytic stomata in all the investigated species of Mendoncia and Thunbergia , as well as in the other genera of the Acanthaceae, is considered as significant. The retention of Mendoncioideae and Thunbergioideae as subfamilies of the Acanthaceae is justified from the present investigation.     

Observations on the cotyledonary and hypocotyledonary stomata and trichomes in some Caesalpiniaceae with a note on their taxonomic

The structure and ontogeny of stomata on cotyledons and hypocotyls and the trichomes on hypocotyl are accounted for in eighteen species of Caesalpiniaceae. Trichomes are eglandular, bi- rarely tri-celled, smooth walled or walls wavy with cuticular striations or tubercles. Anomocytic, haplocytic, paracytic, diacytic, transitional, tetracytic, tricytic and cyclocytic stomata occur in different combinations even on the same surface of the cotyledon. In all, there are fourteen combinations. Inspite of the diversity, the most frequent type is anomocytic in most of the species and paracytic in some species of Cassia and Delonix (abaxial) but rarely it is haplocytic or anisocytic. In hypocotyls it is anomocytic. Ontogenetically anomocytic, tetracytic and cyclocytic stomata are perigenous, whereas other types are mesogenous or mesoperigenous. There is an increase in the number of subsidiary cells by their division or the neighbouring perigenes assuming their shapes. About eight such types are described. A pair of stomata has a common subsidiary cell. Twelve types of guard cell and stomatal approximation abnormalities are described. A range in the number, size and shape of the nuclei in guard cell are recorded. Megastomata (giant stomata) are observed in Parkinsonia and Tamarindus. The taxonomic significance of the stomata is also discussed.     

Stomatal Features in the Leaf of Aganosma dichotoma (Roth) K. Schum

Paracytic and anisocytic types of mature stomata are found inthe leaf of Aganosma dichotoma. Stomata with one guard cell,stomata with degenerated guard cells, and contiguous stomataare common. Stomata with arrested pore development are alsofound in certain cases. A single guard cell without any porehas not been designated as a stoma with one guard cell in thepresent investigation. Ontogeny of contiguous stomata have beentraced. Subsidiary cells are, morphologically, just like theircontiguous guard cells. Subsidiary cells may retain their shapeand contents even when their contiguous stoma becomes mature,or may change their shape and lose their contents. They mayor may not divide. Subsidiary cells form a whorl of more thantwo subsidiary cells around a stoma by their divisions. Degenerationof guard cell(s)— their contents and nuclei—havebeen traced. In certain cases guard cells divide forming morethan two guard cells associated to a single pore. Cytoplasmicconnections are found between two guard cells of nearby stomata,and between a guard cell and an epidermal cell. Near the wound,the epidermal cells over the veins become meristermatic givingrise to new epidermal cells but no meristemoid.     

Action of growth regulators on the cotyledonary stomata ofCucumis sativus L.: Structure and ontogeny

Anomocytic stomata and stomata with single subsidiary cells are commonly observed Sometimes a stoma appears anisocytic. Double cytoplasmic connections between nearby stomata and division of guard cells with persistent or degenerating nuclei are seen in GA. One or more divisions of guard cells, displaced guard cells and single guard cells with or without pore are noticed in SUC. Formation of single guard cells is a common feature in TIBA. Paracytic stomata, one and a half stomata and persistent stomatal initials are seen in SUL. COUM seems to be not inhibitory inCucumis sativus. In COL stomata with unequal guard cells, unequal stomatal cells with thickening in between but without intervening pore, stoma with double pores, persistent stomatal initials which may be solitary or in groups with varying shapes and with one or two nuclei of different shapes are noticed. The growth regulators affect the frequency of stomata, epidermal cells; stomatal index; size of guard and epidermal cells.     

Epidermal structure and development of stomata in vegetative and floral organs ofHybanthus enneaspermus (Linn.)F. Muell

The present paper deals with the epidermal structure and ontogeny of stomata in vegetative and floral organs ofHybanthus enneaspermus. The epidermal cells are either polygonal or elongated with straight, sinuous or arched thick anticlinal walls. The surface of the cuticle shows parallel striations radiating from the guard cells or hair bases. Unicellular and uniseriate bicellular trichomes with verrucose margins have been observed on all organs. The mature stomata are anisocytic, paracytic, anomocytic and transitional between anisocytic and paracytic. The ontogeny of anisocytic and paracytic stomata is syndetocheilic or mesogenous, anomocytic is haplocheilic or perigenous, while that of the transitional type is mesoperigenous. Four types of stomata have been observed on all the vegetative and floral organs and their ontogeny from organ to organ of this plant is constant. Stoma with a single guard cell is the result of disintegration of one of the guard cells before or after pore formation. Contiguous stomata are also occasionally noticed.     

Some Observations on the Diversity of Stomata and Trichomes in Six Species of Dioscorea

Stomata and trichomes are described on the leaves of six speciesof Dioscorea. As many as six types were found in D. bulbiferaand D. oppositifolia, four types in D.hispida and D. wallichii,three types in D. belophylla, but only two types in D. alata.Although there is a diversity of stomata even on the same surface,the predominant type is anomocytic in all the species exceptD. bulbifera in which it is tricytic. Rarely a stoma is alsocyclocytic in D. bulbifera. An increase in the number of subsidiarycells in paracytic, tricytic, or diacytic stomata takes placeby the wall formation in them. Similarly a reduction in thenumber of subsidiary cells of a tetracytic stoma is the resultof lateral subsidiary cells assuming the form of epidermal cells.Abnormalities such as a stoma with one guard cell, degenerationof guard cells, and contiguous stomata are also met with. Theorganization of different types of stomata is studied in D.bulbifera and D. wallichii and shown to be perigenous. Capitateglandular hairs were seen on the leaves of D. belophylla, D.bulbifera, D. hispida, and D. wallichii but non-glandular, uniseriate,3-celled trichomes were observed only in D. hispida.     

Stomatal opening by fusicoccin is accompanied by depolymerization of actin filaments in guard cells

Actin in guard cells is assembled in a radial pattern when stomata are induced to open under light, but the filaments are disassembled when stomata are closed under darkness or by abscisic acid (S.-O. Eun and Y. Lee, 1997, Plant Physiol. 115: 1491–1498). To test if signals that open stomata commonly generate the polymerized form of actin in guard cells, leaves of Commelina communis L. were treated with a potent stomatal opening agent, fusicoccin, and the actin organization examined by immunolocalization techniques. When stomata were induced to open by fusicoccin, hardly any of the filamentous form of actin was detected; instead, the actin resembled that present in guard cells that had been treated with an antagonist to actin filaments, cytochalasin D, and showed a sharp contrast to the long filaments developed in illuminated guard cells. Furthermore, treatment of illuminated leaves with fusicoccin disintegrated actin filaments that had already been formed in the guard cells. Preincubation of leaves with phalloidin, which interferes with fusicoccin-induced actin depolymerization, delayed fusicoccin-induced opening during the early phase. These observations suggest that the prevention of actin filament formation and/or depolymerization of actin filaments may accelerate the stomatal opening process in response to fusicoccin. Received: 1 October 1999 / Accepted: 29 November 1999     

Structure,Ontogeny and Taxonomic Significance of Stomata in Some Cucurbitaceae

Stomatal structure, ontogeny in vegetative and floral organs of 9 genera and 12 species of Cucurbitaceae are described. The stomatal types conform to aperigenous, monoperigenous, diperigenous, hemipara-mesoperigenous and para-mesoperigenous types of Fryns-Claessens & Van Cotthem (1973). Stomatal abnormalities such as contiguous stomata, single guard cells with or without pore, one and a half stomata, degeneration of one or both the guard cells, cytoplasmic connections between guard cells of neighbouring stomata and a guard cell of a stoma and an adjacent epidermal cell, and division of guard cells are described. Stomata index, frequency of stomata, epidermal cells, size of guard and epidermal cells and organwise distribution of stomata are given. Stomatal studies does not support the view that the Cucurbitaceae are related to the Passifloraceae. The inclusion of 9 genera and 12 species studied in the tribe Cucumerineae is justified.     

A scanning electron microscope study of normal and vitrified leaves from Datura insignis plantlets cultured in vitro

The surface anatomy of normal and vitreous leaves of plantlets obtained from Datura insignis Barb Rodr nodal segment cultures was compared using scanning electron microscopy. Normal and vitrified leaves are similar in several ways. They are both amphistomatic, and have similar distributions of glandular and non-glandular trichomes. Stomata have similar length, diameter and distribution in normal and vitreous plants. Immature stomata, which have closed pores, and plugged stomata, which contain an amorphous material between their guard cells, occur in both normal and vitrified leaves. Normal and vitreous leaves differ in the frequency of normal and abnormal stomata. Normal stomata have kidney-shaped guard cells and resemble closely those found in field-grown plants, whereas abnormal stomata have deformed guard cells. Normal stomata represent approximately 80% of the total number of stomata in normal leaves, but only 7% of the total number of stomata in vitreous leaves. Abnormal stomata represent 90% of the total number in vitreous leaves. The deformation of guard cells could possibly be a mechanical impediment to stomatal function.     

Structure and development of stomata on the primary root of Ceratonia siliqua L

Stomata of various sizes are produced on the primary root of Ceratonia siliqua L. Most are generated during embryogenesis, prior to seed desiccation. They can be detected on the dry embryo in a wide zone just above the root tip. Initially, large stomata are formed. These have the ability to induce divisions of their neighbouring cells, creating particular cell patterns around them. Later, small perigenous stomata are generated. As the root grows following seed germination, the stomatal zone overlaps with that of the root hairs. Although root stomata of C. siliqua undergo a structural differentiation that seems almost identical to that of the elliptical stomata formed on leaves, they are unable to move and remain permanently open. Polarizing microscopy of fully differentiated stomata and young stomata at the stage of stomatal pore formation revealed deposition of radial cellulose microfibril systems on their periclinal walls. However, these systems were less developed than those on leaf stomata, a feature that might be responsible for their inactivity. Besides, plastids of the root guard cells (GCs) do not differentiate into chloroplasts but function solely as amyloplasts. Root stomata have a short life span. During rapid and intense root growth, GCs cannot keep pace with the elongation of their neighbouring rhizodermal cells. They therefore split in their mid-region, transversely to the stoma axis. The two parts of the transversely torn stoma are dragged apart and a large opening is formed on the root surface, just above the substomatal cavity. The root stomata, together with these openings, may facilitate increased gaseous exchange during respiration and/or an increased transfer of some nutrients and water in the rapidly growing primary root.     

Structure and Development of Stomata on the Vegetative and Floral Organs in Some Members of Caesalpiniaceae

The structure and development of stomata in 19 species of thefamily Caesalpiniaceae are described. The study is mostly confinedto the leaves, but observations have also been made on othervegetative and floral organs of some species Stomata may beparacytic, anisocytic, anomocytic, and with one subsidiary cell.Occasionally a stoma is diacytic, cyclocytic, or actinocytic.Different types occur individually or may be found side by sideeven on the same surface of an organ. The most prevalent typein all the genera is paracytic except in Caesalpima where itis anomocytic. The development of an anomocytic stoma is perigenous,but those with subsidiary cells are largely mesogenous; rarelyparacytic stomata are mesoperigenous. In spite of diversityof stomata, different types of stomata have similar patternsof development in different organs of the same plant. The presentinvestigation also indicates that the inconstancy of stomatain the family is due to (a) their diversity and (b) an increasein the number of subsidiary cells either by their division orby the neighbouring perigenes becoming subsidiary cell-like.     

HELICOCYTIC AND ALLELOCYTIC STOMATA: UNRECOGNIZED PATTERNS IN THE DI COTYLEDON AE

Two new mesogenous stomatal patterns are described for the Dicotyledonae: helicocytic, with a helix of four or more subsidiary cells surrounding the guard cell pair, and allelocytic, with an alternating complex of three or more C-shaped subsidiary cells of graded sizes. The latter pattern may have guard cells developed parallel to the subsidiary cells (parallelocytic) or at right angles to them (diallelocytic). For both types, the complex development of regular sequences of mesogene subsidiary cells with particular attributes of size and arrangement provides strong probability of correlated ontogeny and adult pattern. They are related to mesogenous forms of the anisocytic, paracytic and diacytic patterns, but these latter may also be developed in different ways. The use of stomatal pattern data for taxonomic and evolutionary studies of dicote is discussed.     

Epidermal Structure and Stomatal Development in Some Malvaceae and Bombacaceae

Epidermal structure and development of stomata in 15 speciesof the Malvaceae and two of Bombacaceae are described. The cellsof the epidermis are polygonal, isodiametric, or elongated withthick, straight, arched, or sinuous anticlinal walls and containchloroplasts and abundant druses of calcium oxalate. Cuticularstriations radiating from the guard cells or hair bases arenoticed. Six types of glandular and non-glandular trichomesare seen. The mature stomata are anomocytic, anisocytic, andparacytic in the members investigated of both the families.The ontogeny of anisocytic and paracytic stomata is syndetochelicor mesogenous, while that of anomocytic is haplocheilic or perigenous.An abnormal stoma with a single guard cell is also observed.An increase in number of subsidiary cells in anisocytic stomatais due to the division of the subsidiary cells.     

利用激光扫描共聚焦显微镜研究拟南芥气孔发生与发育

通过激光扫描共聚焦显微镜,利用不同种类(波长)的激光研究拟南芥叶片气孔发生与发育。结果表明,利用紫外激光(351nm)扫描可以清楚观察到拟南芥表皮各种细胞及其发生发育的形态变化,包括表皮毛细胞、副卫细胞、保卫细胞、铺垫表皮细胞等。气孔发生过程中,首先原表皮细胞不对称分裂产生拟分生组织和副卫细胞,接着分化出保卫细胞母细胞,进一步发育形成保卫细胞,最终形成气孔器。气孔分化完成后,保卫细胞在紫外激光下不产生荧光,但利用蓝光激发(488nm)辅助荧光素染色,可清晰地看到保卫细胞。结果表明,激光扫描共聚焦显微镜在拟南芥叶表皮细胞形态研究上有独特的功能。