Epidermal Structure and Stomatal Ontogeny in Some Eusporangiate Ferns

Cuticles, mature epidermis, and stomatal ontogeny in some speciesof the three genera of Ophioglossaceae and in Angiopteris evectawere studied. Development of stomata is perigenous in all Ophioglossaceaebut it is mesoperigenous (Piper type) in A. evecta.     

Epidermal Structures and Stomatal Ontogeny in Some Mimosaceae

The structure of trichomes and stomata on leaflets of 21 speciesof the Mimosaceae are described. Non-glandular trichomes inMimosa pudica are of three types: unicellular, with a roundedthick-walled base and a terminal unicellular body, and multicellular.Capitate, clavate, or cylindric, 3–6-celled glandularhairs are observed on leaflets of Mimosa pudica only. Leafletsare amphistomatic in all species except Adenanthera pavonina,Calliandra sp., Parkia biglandulosa, Pithecellobium dulce, andSamanea saman in which they are hypostomatic. Only paracyticstomata are found in Leucaena leucocephala and Mimosa pudica.In the rest stomata are of more than one type. In spite of thediversity, the most frequent type in these species is paracytic.Anisocytic stomata, in all cases, are secondarily derived fromparacytic ones by transverse or oblique wall formation in asubsidiary cell. Similarly some stomata with one subsidiarycell are also secondary derivatives of the paracytic ones becauseof one of the subsidiary cells assuming the form of an epidermalcell. The development has been traced in 14 species and thatof paracytic stomata may be mesogenous or mesoperigenous, thatof stomata with one subsidiary cell mesogenous but anomocyticstomata are ontogenetically perigenous. Occasionally a meristernoidis cut off from one of the subsidiary cells of a paracytic stoma.The organization of a stoma from such a meristemoid has beentraced.     

Epidermal Structure and Stomatal Ontogeny of Anemia Spp.

This paper describes the cuticle, epidermis, and the differentkinds of stomata met with in three species of Anemia.Observationsmade on the ontogeny of the Anemia type or ‘floating’stomata in A. rotundifolia show that their meristemoids giverise to a guard cell mother cell by the formation of a periclinalwall as suggested earlier by other workers.     

Epidermal Structure of Psilotales and Stomatal Ontogeny of Tmesipteris tannensis Bernh.

Mature epidermis and cuticles of the two genera of Pailotales,viz. Psilotum nudum and Tmesipteris tannensis and the stomatalontogeny of the latter are described.     

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.     

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 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 Leaves of Anagallis arvensis, L.

Epidermal structure and development of stomata in leaves ofAnagallis arvensis has been described. The stomatal ontogenyis of the mesoperigenous type.     

Epidermal Structure and Ontogeny of Stomata in Vegetative and Reproductive Organs of Ephedra and Gnetum

The epidermal structure and development of stomata in vegetativeand reproductive organs of Ephedra foliata and Gnetum ula isdescribed. The epidermal cells are polygonal, isodiametric,or elongated with thick or thin straight, arched, or slightlysinuous anticlinal walls. The cuticle is thin or thick. Papilla-likeunicellular outgrowths are present in Ephedra foliata. The maturestomata are orientated parallel to the longitudinal axes orirregularly. The mature stomata are anomocytic, paracytic, witha single subsidiary cell, cyclocytic, and actinocytic. Arresteddevelopment, contiguous stomata, and stomata with aborted guardcells have been observed. The ontogeny of stomata on differentorgans of these two plants is typically haplocheilic or perigenousbut the stomatal apparatus varies from organ to organ.     

The Stomatal Ontogeny and Structure of the Liassic Pteridosperm Sagenopteris (Caytoniales) from Hungary

Stomatal ontogeny is often inferred but rarely documented for extinct fossil plants because it requires observations from young leaves that are rarely preserved as fossils. The discovery of several very young leaves of the Jurassic plant Sagenopteris (Caytoniales) in the Mecsek Mountains (southern Hungary) in a good state of preservation provides the opportunity for studying the stomatal ontogenesis of this genus. The specimens show perigenous anomocytic stomata. This feature confirms the evolutionarily high position of Sagenopteris among fossil gymnosperms and supports the opinion that the ancestors of angiosperms and some groups of pteridosperms might be closely related. Such clear examples of stomatal development have not previously been documented for fossil material.     

Epidermal and Guard Cell Interactions on Stomatal Aperture in Epidermal Strips and Intact Leaves

Despite the observation first made by von Mohl in 1856, thatepidermal cells greatly influence stomatal aperture, subsequentstudies have failed to pay adequate attention to epidermal cellviability or to quantify the degree of its influence on aperturein epidermal strips and leaf sections. Using Vicia faba stripsand leaf sections we found the following: (i) a non-linear relationshipbetween aperture and guard cell contact with live epidermalcells; (ii) epidermal cell viability on isolated strips hada threshold at about 25 °C; (iii) epidermal strips withdead epidermal cells had wider apertures and lower variabilitythan strips with live cells or intact leaf sections; (iv) afterepidermal cell viability was accounted for, stomatal aperturesshowed no significant differences between isolated strips orstrips removed from leaf sections treated in the same manner;(v) highly variable apertures appeared to be the normal conditionof the intact leaf. Caution should therefore be used in interpretingstomatal behaviour from epidermal strips without first takinginto account mechanical interactions between the guard and surroundingepidermal cells. Vicia faba L, broad bean, epidermal strips, leaf impressions, stomata, guard cells, temperature effects     

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.     

Circadian Rhythm of Stomatal Movements in Epidermal Strips

Measurements were made of changes in stomatal pore widths inepidermal strips of leaves ofVicia faba and Commelina communis.Strips were incubated in dilute KCI solutions (1 and 10 molm^–3) flowing through a perfusion chamber on the stageof a microscope and kept for 4 d in continuous light. Circadianrhythms of stomatal apertures were detected in both species.Although the amplitude was small it was statistically significant.It is concluded that at least partof the mechanism for the stomatalrhythm resides in the epidermis, probably in the guard cells. Key words: Cireadian rhythm, epidermal strips, stomata     

合意非洲铁羽片表皮及气孔器的发育研究

用光学显微镜和扫描电镜对合意非洲铁羽片表皮及气孔器的发育过程进行观察研究。结果显示,(1)在羽片发育过程中表皮细胞变化不明显,主要是细胞伸长和壁增厚的过程;表皮的角质层连续出现。(2)气孔器发育可大致分3个阶段:保卫细胞母细胞阶段、幼保卫细胞阶段和成熟保卫细胞阶段;气孔器发育方式为单唇型或周源型;成熟气孔器属单环型。(3)在羽片发育过程中,气孔密度起初很低,后急剧升高并达到峰值,之后逐渐下降并趋于稳定。(4)有早熟气孔器。(5)羽片表皮发育成熟的方式是由基部向顶部逐步推进。     

Circadian Stomatal Rhythms in Epidermal Peels from Vicia faba

Circadian rhythms in stomatal aperture and in stomatal conductance have been observed previously. Here we investigate circadian rhythms in apertures that persist in functionally isolated guard cells in epidermal peels of Vicia faba, and we compare these rhythms with rhythms in stomatal conductance in attached leaves. Functionally isolated guard cells kept in constant light display a rhythmic change in aperture superimposed on a continuous opening trend. The rhythm free-runs with a period of about 22 hours and is temperature compensated between 20 and 30°C. Functionally isolated guard cell pairs are therefore capable of sustaining a true circadian rhythm without interaction with mesophyll cells. Stomatal conductance in whole leaves displays a more robust rhythm, also temperature-compensated, and with a period similar to that observed for the rhythm in stomatal aperture in epidermal peels. When analyzed individually, some stomata in epidermal peels showed a robust rhythm for several days while others showed little rhythmicity or damped out rapidly. Rhythmic periods may vary between individual stomata, and this may lead to desynchronization within the population.     

Structure,Ontogeny, Classification and Organographic Distribution of Trichomes in Some Cucurbitaceae

The structure, ontogeny, classification and organographic distribution of trichomes in 9 genera and 12 species of the Cucurbitaceae are presented. The vegetative and floral trichomes are classified into glandular and non-glandular. In all 13 main types and 26 subtypes of glandular and nonglandular trichomes are observed. All the types of trichomes originate from a single papillate hair initial. The trichomes are classified on the basis of form, structure and contents.     

The Cuticle, Epidermis and Stomatal Ontogeny of Casuarina equisetifolia Forst

The cuticle, epidermis and stomatal ontogeny of Casuarina equisetifoliaForst. is described. The cuticle shows well marked impressionsof the epidermal cells and stomata. The epidermis of leaf andstem shows transversely oriented, tetracytic, mesoperigenousstomata with two lateral mesogene subsidiaries and two polarperigene neighbouring cells. Although the epidermal structureof Casuarina shows a good deal of resemblance with that of theBennettitales, it may not indicate any phylogenetic relationshipssince there are important differences in the structure and reproductionof the plants of these two groups.     

The Role of the Epidermal Cells in the Stomatal Movements

The water deficit of the leaves, the osmotic values of the stomatal cells and epidermal cells at incipiment plasmolysis, as well as the width of the stomatal apparatus and pore opening, were measured every hour from 6-17 o'clock under natural environmental conditions. During the noon hours, the intensity of light in clear weather ranged from 40,000-55,000 lux in the open position, and from 15,000-20,000 lux in the shade. The temperature was usually 15–20°C. The experimental object was Vicia Faba growing in a field, both plants freely rooted and plants in pots buried in the soil. The experiments resulted in the following observations and conclusions: 1. When leaves are exposed to strong light, the osmotic value at incipient plasmolysis changes not only in the guard cells, but also in the epidermal cells. If the epidermal cells' osmotic value rises, water is sucked from the guard cells and their uptake of water by suction is decreased, which promotes closure and counteracts opening, respectively. If the value falls, the effect is the reverse. The guard cells react passively to these epidermal changes. The passive stomatal movement eliciteed in this way has therefore been denoted as “osmopassive”, in contrast to the long known passive movement caused by a change in turgor of the epidermal cells, and which has therefore been denoted as “turgorpasslve”. The osmopassive component of stomatal closure has an earlier and more rapid onset than the hydroactive closing reaction, which consists of a decrease in the guard cells' osmotic value. Stomatat closure often starts with the osmopassive rapid process, and is completed and stabilized by the hydroactive process. It has not been possible to determine whether the osmopassive closing reaction is identical with the rapid reaction previously described, and interpreted as of adenoid nature, and tlius belonging to the active group. 2. The osmotic potential of the guard cells - i.e., the difference between the osmotic value of guard cells and epidermal cells at incipient plasmolysis - is, therefore, formed not only by a cbange in the osmotic value of the former cells, but also by a cbange in that of the latter. 3. Although the pore width runs largely parallel to the osmotic value of the guard cells, there is greater agreement between pore width and osmotic potential. When the water deficit of the leaf exceeds a certain threshold value, potential and stomatal width start to decrease. Closure is completed when the fall in potential approaches the zero value. If the water deficit subsequently continues to increase, the potential becomes negative and the stomata remain closed. 4. The stomatal movements are regulated by physiological processes which form two kinds of equilibrium between increase and decrease of the osmotic potential of the guard cells, i.e. the osmopassive increase - osmopassive decrease and the photoactive increase - hydroactive decrease. These equilibria complement each other in rate and stability. The osmopassive processes start rapidly and as soon as the deficit cbanges; hydroactive closure and sometimes also photoactive opening, are, on the contrary, time-consuming. When the water deficit is suboptimal, turgorpassive opening and closing are superadded, but only in those cases in which the osmotic potential of the guard cetls is positive.     

Release of Malate from Epidermal Strips during Stomatal Closure

Isolated epidermal strips of Vicia faba and Commelina communis release malate into their bathing medium when stomata close. This release was largest (about 0.6 of the initial malate content) when epidermal strips of C. communis were floated on 10⁻⁵ M (±)-abscisic acid.     

Energy Supply for Stomatal Opening in Epidermal Strips of Commelina benghalensis

The influence of light or darkness on stomatal opening in epidermal strips of Commelina benghalensis was evaluated in the presence or absence of O₂ and/or metabolic inhibitors. Opening was restricted in nitrogen and was promoted by NADH and acids of the tricarboxylic acid cycle (succinate and α-ketoglutarate) in CO₂-free air in light as well as in darkness. The enhancement by light of stomatal opening was prevalent under nitrogen or in the presence of the respiratory inhibitors (sodium azide and oligomycin). Respiratory inhibitors decreased the opening in light or darkness under CO₂-free air but exhibited no effect under nitrogen, whereas phosphorylation uncouplers were inhibitory in light or darkness under both CO₂-free air and nitrogen. The results suggest that oxidative phosphorylation is a basic source of energy for stomatal opening, although photophosphorylation could be an energy source.