Leaf Anatomy of Androstachys johnsonii Prain and its Functional Significance

The anatomy of the lamina and petiole of Androstachys johnsoniiis described. Most notable features are: (1) the variabilityof the vascular anatomy of the petiole; (2) the upper epidermisof the lamina which consists of large cells some of which arepericlinally divided and project into the mesophyll; (3) a complexpattern of unlignified sclereids which, it is suggested, shouldbe referred to as gelatinous sclereids and which effectivelylink the veins with the two epidermises; (4) unique trichomes,clothing the abaxial surface, which consist of a long upper,relatively thin walled cell and a thick walled basal cell. Thiscell, apparently according to the level of water stress in theleaf, is either completely sap filled or else contains a bubbleof gas. It is suggested that this may act as a one-way watervalve allowing water into the leaf via the trichome but preventingthe outward passage of water. These and other aspects of anatomyare discussed in relation to the characteristic environmentalrequirements of the species. Androstachys, cuticle, dry forest, gelatinous fibres, perforation plates, trichomes, savannah, sclereids, stomata, water stress     

Foliar sclereids in Memecylon and Lijndenia (Melastomataceae) from Borneo, Java, Malaya and Sumatra

Foliar sclereids are investigated in 41 Memecylon species and in Lijndenia laurina Zoll. & Mor. (= Memecylon oligoneurum Bl.). The predominance of filiform sclereids in the Memecylon species is remarkable. Lijndenia laurina has ramiform sclereids.     

On Arborescence in Gahnia clarkei and Gahnia sieberiana

Specimens of Gahnia sieberiana from Brisbane, Queensland, andof Gahnia clarkei from near Orbost, Victoria, were collectedand examined both morphologically and anatomically. The speciesgrow in wet areas and are of interest because they representthe largest arborescent species known in the Cyperaceae. Stemdiameters up to 120 mm and stems up to 10 m long have been observed.Such long stems tend to be supported by nearby vegetation. Althoughfresh stems are tough and woody, they are brittle. Branchingof the stems is sympodial, and numerous branches are producedby plants growing in exposed habitats. There is less branchingin plants from shaded habitats. Basal shoots may also occur.Adventitious roots develop basally on most plants, but withG. sieberiana, some adventitious roots form near the shoot apexand grow in and around leaf bases. Anatomical features of interestare an endodermoid layer composed of sclereids with elongate,undulated, outer tangential walls that are lignified and suberized,short vessel elements with horizontal to oblique simple perforationplates, and relatively short sclereids surrounding vessel elementsin the vascular bundles. Some vascular bundles are bipolar.The presence of short vessel elements here is in marked contrastto the longer tracheary elements in other arborescent monocotyledons. Arborescence, stem anatomy, Cyperaceae, Gahnia, saw sedge, Monocotyledon, bipolar bundles, morphology, endodermoid layer     

A study of Foliar Anatomy of Gnetum parvifolium

The present research was undertaken to examine the foliar anatomy of Gnetum parvifolium (Warb.) C. Y. Cheng ex Chun. It is hoped that the observations may contribute to provide additional evidence for identification on Chinese species of this genus. A special morphological features inside of epidermal anticlinal wall designated here as the globose cuticular sac, and is the special feature of this epidermis not yet reported in this genus. During the course of an investigation on sclereid type of leaf in this species I observed the striking type of these cells in cleared leaf preparations, viz. filiform sclereids (368–624 μm long, 10 μm broad), one not hitherto described for any other species in this genus.     

Developmental Morphology of Platycerium coronarium (Koenig) Desv

The growth habit and certain developmental aspects of Platyceriumcoronarium (stag's horn fern) are described. Starting from theprimordial stage, the nest and pendulous leaves develop to maturityin 90 and 80 days respectively. The fertile lobe, which is partof the pendulous leaf, reaches its maximum size in 40 days.The morphogenesis of the nest leaf is more variable, and itmatures and deteriorates earlier than the pendulous leaf. Theacrostichoid sorus formation is completed in 3 weeks from inceptionand spore dispersal takes place when the fertile lobe is about100 days old. The area of the fertile lobe and number of sporesproduced were determined. On Knop's agar medium the gametophytesdevelop in 2 months and 85 per cent of them are unisexual (bothmale and female) and 15 per cent bisexual. Less than 1 per centof the gametophytes give rise to sporophytes. The juvenile leavesare simple, displaying open dichotomous venation; the firstnest and pendulous leaves are produced 24 months after the dateof spore germination. Platycerium coronarium, stag's horn fern, leaf development, morphogenesis, spore production     

ONTOGENY OF THE FOLIAR SCLEREIDS IN NYMPHAEA ODORATA

Gaudet, John. (U. Rhode Island, Kingston.) Ontogeny of the foliar sclereids in Nymphaea odorata . Amer. Jour. Bot. 47(7): 525–532. Illus. I960.—The “diffused” idioblastic sclereids develop in the leaves of Nymphaea odorata Ait. during periods when leaves are forming on the shoot apex, and they are initiated by cells which are differentiated from other cells of the fundamental tissue by nuclear size. The ontogeny of the sclereids is similar in most cases, but differences are apparent among petiolar, laminar and stipular types, especially, when the adult morphology is considered. At maturity, the sclereids are usually pitted in the central portion, and they do not show “polarity” in the leaf or orientation near the tracheary elements, which occur in the same tissue. The “spicule-like” protuberances and the angular cross-sectional shape of the stipular sclereids are interpreted as evidence that growth of these sclereids was restricted as compared to other types of sclereids which were not restricted.     

The Development of the Runner Bean Leaf with Special Reference to the Relation between the Sizes of the Lamina and of the Petiolar Xylem: III. The Development of the Leaf under Various Conditions

The development of the first pair of leaves of the Runner Bean(Phaseolus multiflorus Willd.) under various conditions is described. 1. Under damp conditions and also when one leaf of a pair wascovered with a black paper envelope, the rate of developmentwas altered but no significant changes in the relative developmentof the parts of the leaf occurred. 2. Removal of a portion of the lamina at an early stage of developmentresulted, at maturity, in a leaf having relatively less petiolarxylem, although the ratio xylem area/lamina area was slightlyhigher. This treatment also delayed a ‘sudden’ increasein area of the vessels which was seen in normal plants. 3. An attempt was made to estimate the transporting power ofthe petiolar xylem and to compare it with the lamina area. Thedata suggest that the maximum possible area of the lamina atany stage in development may be determined by the transportingpower of the xylem, but that the attainment of this maximumpossible area may be prevented by external factors as is seenin some of the experimental results presented.     

Light-guiding function of foliar sclereids in the evergreen sclerophyll Phillyrea latifolia: a quantitative approach

The anatomy and orientation of the foliar sclereids of the evergreen sclerophyll Phillyrea latifolia suggest a light-guiding function. Light microscope observations of enzymatically isolated sclereids showed that they possessed very thick cell walls, lobes and branches which occurred mainly at the end of the idioblasts reaching the abaxial epidermis. Leaf cross-sections showed that sclereids occurred diffusely within the mesophyll and were oriented vertically with respect to the lamina. In paradermal sections, the cut cell walls of the sclereids appeared as bright light spots among the dark-green background of the mesophyll cells. The heterogeneity of the radiation field transmitted through the same paradermal section was quantified by image analysis and two- or three-dimensional representations. The amount of light transmitted through the sclereids was found to be up to 30-fold higher compared to that transmitted through the neighbouring mesophyll cells. The light guiding capacity of the sclereids at the spongy mesophyll level was estimated to be 40-80%. In leaves illuminated from the adaxial surface, light passing through the ends of the sclereids seemed to be reflected from the internal surface of the abaxial epidermis. In sunny conditions when leaf thickness tends to increase, the number of sclereids per unit leaf area was increased significantly compared to the shaded ones. It is proposed that the anatomy and orientation of the foliar osteosclereids of P. latifolia, are suitable for a light-guiding function. Thus foliar sclereids, besides other roles, may contribute both qualitatively and quantitatively, to the enhancement of the light microenvironment within the mesophyll of these sclerophyllous leaves.Keywords: Phillyrea latifolia L. (incl. P. media L.), foliar sclereids, light guiding, image analysis.      

The Development of the Fruit Walls in Carya

Both the pistillate flowers and the developing fruits of CaryaovataandC. cordiformis are covered with secretory and protectivehairs. There are two kinds of the secretory hairs. In the morefrequent one the volatile oils are accumulated under the cuticlecovering the cells of the head. In the other the secretory substancesare accumulated inside the cells. The flowers and the developingfruits of the two investigated species have quite large emergenceson which the stomata most often occur. During the developmentof the fruit lenticels are formed in the green hull. Tanninsare accumulated not only in the green hull, but also in thecarpellary layer and in the packing tissue. There are some differences between C. ovata and C. cordiformisin the course of sclerification of the green hull. In C. cordiformisthe hull is less sclerified than in C. ovata, and the sclerificationof the carpellary layer occurs later. At a certain period ratherlarge gaps are present in the lignifying shell (in the regionsof the sutures) where the cells have thin cellulose walls. Thesegaps are partly filled with sclereids. The gaps become reducedto narrow chinks, in which the cell walls remain unlignified.The hard shell is not formed in all its width at the same time.During the process of formation of the hard fruit shell theremay arise single sclereids surrounded by thin-walled cells.Within a short time these undergo a similar modification andthe tissue becomes uniform as sclerenchyma. The sclereids ofthe hard shell have, in general, strongly folded cell walls.Owing to this they overlap each other.     

Regeneration of Sclerenchyma in Wounded Dicotyledon Stems

When the sclerenchyma cylinder that surrounds the vascular cylinderin many dicotyledon stems is interrupted by cutting away oneside of an internode, its continuity becomes restored in somespecies by the differentiation of sclereids within the woundcallus. These sclereids, which may be scattered or arrangedin clumps or in a continuous sheet, lie in a zone within the‘cortical’ parenchyma between the regenerated vascularcylinder and the wound cork. The amount and especially the arrangementof regenerated sclerenchyma tends to reflect that of the originalprimary sclerenchyma cylinder in the unwounded stem, exceptthat longitudinal continuity is poorly developed and all fibresare replaced by sclereids. Syringa vulgaris L, lilac, regeneration, differentiation, fibres, sclereids, sclerenchyma, positional control     

The Effect of Temperature on Growth and Development of Echinochloa Millets

Accumulation of dry weight and leaf plus stem area were measuredin Echinochloa utilis and E. frumentacea grown at temperatureregimes from 15/10°C to 33/28°C (day/night). Tilleringand height were recorded in addition to leaf number which wassubsequently used as a developmental index. In both species shoot dry weight increased with temperatureup to 33/28°C; the increase in relative growth rate (RGR)was negligible above 27/22°C. Below 27/22°C the RGRof E. frumentacea decreased sharply and at 15/10°C it madeno effective growth. At low temperatures the RGR of E. frumentaceawas lower than that of E. utilis due to slow leaf area expansion,and in particular smaller individual leaves. E. frumentaceatillered more than E. utilis. Plant development was retardedat low temperatures but was not as responsive to temperatureas dry weight and leaf area. The different responses to temperatureof the two species were described in equations suitable forinclusion in predictive growth models. Echinochloa spp., millet, growth, development, temperature, relative growth rate     

Suggested Amendments in Growth Analysis and Potentiality Assessment in Relation to Light

It is suggested that dry-weight accumulation, productivity ofunit leaf area and leaf-growth be measured by the availablelight energy instead of time scale. Potential photosynthesis(ap), as calculated by de Wit, is considered to be the mostsuitable form. The implementation of the new technique is discussedand the characteristics thereby obtained denoted as PhotosyntheticProductivity (PP), Leaf Area Efficiency (LEF), and Leaf AreaExtension Rate (LEX) respectively. The above technique was adoptedby the author in some experiments and the results conform withthe expectation. The critical leaf area varies with the angleof sun above the horizon. The Photosynthetic Productivity liesbetween the limits 0–0.95. It increases with increasingleaf area until its maximum, while LEF decreases from 0.95 downwards.LEX is greater at low light values, especially with higher temperatures. It is suggested that the critical leaf area index (Le), by whichthe highest productivity could be obtained if it could be maintainedunaltered, should be distinguished from the leaf area indexwhich provides the most favourable PP during any undisturbedgrowing period, and the latter may be called optimal leaf areaindex (Lo). A procedure based on growth analysis by light scale is described,by which more appropriate evaluation and comparison of grassspecies and varieties may be achieved.     

Leaf and Flower Development in Pea (Pisum sativum L.): Mutants cochleata andunifoliata

The stipule mutant cochleata(coch) and the simple-leaf mutantunifoliata(uni) are utilized to increase understanding of the controlof compound leaf and flower development in pea. The phenotypeof the coch mutant, which affects the basal stipules of thepea leaf, is described in detail. Mutant coch flowers have supernumeraryorgans, abnormal fusing of flower parts, mosaic organs and partialmale and female sterility. The wild-type Coch gene is shownto have a role in inflorescence development, floral organ identityand in the positioning of leaf parts. Changes in meristem sizemay be related to changes in leaf morphology. In the coch mutant,stipule primordia are small and their development is retardedin comparison with that of the first leaflet primordia. Thediameter of the shoot apical meristem of the uni mutant is approx.25% less than that of its wild-type siblings. This is the firsttime that a significant difference in apical meristem size hasbeen observed in a pea leaf mutant. Genetic controls in thebasal part of the leaf are illustrated by interactions betweencoch and other mutants. The mutantcoch gene is shown to changestipules into a more ‘compound leaf-like’ identitywhich is not affected by thestipules reduced mutation. The interactionof coch and tendril-less(tl) genes reveals that the expressionof the wild-type Tl gene is reduced at the base of the leaf,supporting the theories of gradients of gene action. Copyright2001 Annals of Botany Company Pisum sativum, garden pea, leaf morphogenesis, compound leaf, leaf mutants, flower morphology     

Changes in the Levels of Total Soluble Proteins and Sugars During Leaf Ontogeny in Stevia rebaudiana Bert.

Leaf d. wt and the levels of soluble sugars and proteins showa two-phase development during leaf growth in Stevia rebaudiana.The initial large increases in leaf size are due mainly to waterintake up to an area of around 9–10 cm². Increases inabsolute protein content were initially slow though in the secondphase increased it rapidly with dry matter and soluble sugarcontent. In relative terms, however, the concentration of free sugarsdeclined throughout leaf growth. The data indicate that leafprotein synthesis is most probably dependent upon a carbon supplyfrom in situ photo synthesis which only becomes significantat 80 per cent of full leaf area. Stevia rebaudiana Bert., leaf ontogeny, protein content, sugar content     

Comparative study of leaf anatomy of Malaysian species of Chionanthus and Olea (Oleaceae) with special reference to foliar sclereids

The foliar anatomy of 15 Malaysian species of Chionanthus and 3 species of Olea is described and compared with particular reference to sclereids. The anatomy of the two genera is similar except that Chionanthus shows a wider range in sclereid form, eight kinds ofsclereid are recorded. Filiform sclereids are present in all Olea species and most Chionanthus species examined, additional kinds ofsclereid found in these Chionanthus species include astrosclereids, dendrosclereids, osteosclereids and polymorphic sclereids, with brachysclereids of several forms in the petiole. Quantity of sclereids is not related to coriaceousness, which is determined by leaf thickness. Anatomical characters do not support any major grouping of species within Chionanthus and provide further evidence that the sections, Eulinocitra and Ceranthus , are untenable. The distinction between the lepidote scales of Olea and the peltate hairs common to all oleaceous genera is discussed.     

The Influence of Temperature on Leaf Production and Vegetative Growth of Avena fatua

Leaf emergence, leaf area and plant d. wt of Avena fatua wereexamined under a range of constant day/night temperatures ata single light intensity under controlled environment conditions.A simple thermal time analysis was used as the basis for predictingplant growth and development. Multiple regression was used torelate leaf number to mean temperature and to the number ofdays from sowing to 50% plant emergence. From the thermal regressionequations a threshold temperature when growth ceases, the thresholdtime at which seedlings became established and emergence rateand a constant were also estimated. The reciprocals of the durationof leaf expansion and leaf number were linearly related; slopesand intercepts varied with temperature. Relationships were establishedbetween logarithms of leaf area, average temperature and daynumber. Final leaf area increased with average temperature andleaf number. Specific leaf area was inversely related to accumulatedtemperature. The logarithm of d. wt components, average temperatureand number of days from sowing were related; threshold temperature,relative growth rate and a constant were estimated. Parametervalues were compared and contrasted for the measures of growthand development. Shoot/root ratios were not clearly relatedto temperature. The consequences of the models are suggestedparticularly with respect to the formulation of a growth modelfor A. fatua Avena fatua L, wild oat, growth, development, temperature, thermal time     

Growth Analysis of Soybean Seedlings During the Lifespan of the Cotyledons

Patterns of seedling growth of Glycine max in light and darknesswere compared during the period from germination to cotyledonabscission. Fitted growth curves and the derived functions,relative growth rate, unit leaf rate, leaf area ratio and specificleaf area, were used to assess the relative importance in seedlinggrowth of cotyledon storage reserves, cotyledon photosynthesisand leaf photosynthesis. The cotyledons are of an intermediatetype with a predominant storage and a minimal photosyntheticfunction. Cotyledon reserves support seedling growth until theprimary leaves expand, after which growth depends on leaf photosynthesis. Glycine max (L.) Merr., soybean, cotyledons, growth analysis, seedling development     

Day length affects the dynamics of leaf expansion and cellular development in Arabidopsis thaliana partially through floral transition timing

Background and Aims: Plant aerial development is well known to be affected by daylength in terms of the timing and developmental stage of floraltransition. Arabidopsis thaliana is a ‘long day’plant in which the time to flower is delayed by short days andleaf number is increased. The aim of the work presented herewas to determine the effects of different day lengths on individualleaf area expansion. The effect of flower emergence per se onthe regulation of leaf expansion was also tested in this study. Methods: Care was taken to ensure that day length was the only sourceof micro-meteorological variation. The dynamics of individualleaf expansion were analysed in Ler and Col-0 plants grown underfive day lengths in five independent experiments. Responsesat cellular level were analysed in Ler plants grown under variousday lengths and treatments to alter the onset of flowering. Key Results: When the same leaf position was compared, the final leaf areaand both the relative and absolute rates of leaf expansion weredecreased by short days, whereas the duration of leaf expansionwas increased. Epidermal cell number and cell area were alsoaltered by day-length treatments and some of these responsescould be mimicked by manipulating the date of flowering. Conclusions: Both the dynamics and cellular bases of leaf development arealtered by differences in day length even when visible phenotypesare absent. To some extent, cell area and its response to daylength are controlled by whole plant control mechanisms associatedwith the onset of flowering.     

The Dynamics of Leaf Growth and Photosynthetic Capacity in Capsicum frutescens L.

In Capsicum frutescens L. cv. California Wonder the specificleaf weight (dry weight per unit laminar area) at leaf unfoldingis three times higher in the eighth leaf than in the first leafproduced. Intermediate leaves exhibit a trend between the twoThe change in specific leaf weight during laminar expansionis greatest in leaf 1 and least (sometimes zero) in leaf 8.Large changes in specific leaf weight during laminar expansionare associated with a large degree of palisade cell expansion,while leaves showing smaller rates of change have less palisadecell expansion but cell division is more evident. At leaf unfoldingthe fraction I protein content per unit laminar area is higherin upper than in lower leaves. Ribulose diphosphate carboxylaseactivity per unit laminar area and ¹⁴CO₂ fixation per unit laminararea have a similar pattern of development in all leaves andshow no correlation with the changes in specific leaf weight.The peak of activity in all leaves occurs when the laminar areais 10 cm². These results are compared with previous data onlaminar expansion and are seen as in accord with current ideason leaf growth.