bluuebunny/crossref_metadata_2025_split huggingface dataset:
ANALYSIS OF THE SPATIAL DISTRIBUTION OF FOLIAGE BY TWO‐DIMENSIONAL POINT QUADRATS
Authors: WILSON J. WARREN 
Published: May 2006

Summary‘Relative frequency’, yielded by point quadrat analysis of vegetation, is a measure of the area of the foliage in vertical projection. Because this projected area varies according to the foliage angle (i.e. the angle between foliage and horizontal), values of relative frequency fluctuate as attitudes change with environmental variation; also, misleading estimates are obtained when comparisons are made between species of different habit. By using horizontal as well as vertical point quadrats it is possible to estimate the foliage angle and the foliage denseness (i.e. total area of foliage per unit volume of space). If the frequencies of contacts with foliage per unit length of point quadrat are F90 and F0 for vertical and horizontal quadrats respectively, foliage angle (α) is given by tan α/2(F0/F90) and foliage denseness (F) by F=F90 sec α.The vegetation is analysed within horizontal layers. An apparatus is described which can give the required data, and which avoids the errors inherent in point quadrat methods that use needles of appreciable thickness.The total area of foliage per unit area of ground can be obtained by summation of F for all layers.Trials show that the method is practicable in the field, and that it gives values of α and F which reflect the character of the vegetation.Values of F obtained by this method agreed with direct estimates for the same vegetation within 2.5%.Some assumptions made by the method are discussed; provided that certain precautions are taken, the errors resulting from these are small or none.
THE MIRES OF SOUTH WESTERN WESTMORLAND: STRATIGRAPHY AND POLLEN ANALYSIS
Authors: SMITH A. G. 
Published: May 2006

SummaryThe stratigraphy is described of three examples of the ‘Estuarine Moor’ of Munn Rankin (1910). The mires lie on a deposit of estuarine clay. The conclusion of Erdtrnan (1928), that the oldest layers date from Atlantic times, is confirmed. It is shown that the marine transgression represented by the estuarine clay came to an end early in zone VIIa of the pollen analytical zone scheme.The mires began as fens and reedswamps with some open water at first, and later became converted into raised bogs. At two of the sites there was a transition phase of birch fen wood. The transition from fen to bog took place at different times during the Atlantic and Sub‐boreal periods at the three sites. At two sites a boundary horizon in the Sphagnum peat occurs at the opening of Sub‐atlantic times. The relationships between the stratigraphy at the three sites is shown in Fig. 11.Pollen of Tilia cordata is present in quantity throughout the pollen diagrams, except at the base. The curve for Tilia pollen declines at the opening of zone VIII which has been sub‐divided where the Ulrmus curve declines and the Betula curve begins to rise to a maximum. It is suggested that this maximum of the Betula curve is likely to be due to the colonization by Betula of abandoned fields. At the opening of zone VIIIb, abundant pollen of weeds indicates a period of intense agricultural activity; this period occurs at a time when dryness of the bog surface is indicated by retardation layers at least at two of the sites. Pollen of weeds again becomes abundant as recent times are approached. The indications of early agricultural activity are rather sparse, but pollen of Plantago lanceolata is present at the opening of Sub‐boreal time, and the curves for this pollen tend to increase near the opening of zone VIII.
STRUCTURE AND DISTRIBUTION OF SCLEREIDS IN THE LEAVES OF PALMS
Authors: TOMLINSON P. B. 
Published: May 2006

SummaryFoliar sclereids have been found in four genera of palms. They are short, lignified and columnar in Eugeissona, but long, unlignified and fibre‐like in Bactris and Licuala. In Daemonorops hystrix fibre‐like sclereids are present which may be homologous with the fibres sheathing the transverse veins, as is indicated by transitional types found in other species of Daemonorops. The phylogenetic implications of these observations are discussed. Sclereids in palm leaves have no obvious biological function. They are quite useful in diagnosis. Interesting points for comparison between palm leaves and the leaves of the Quiinaceae are reviewed. No development studies have been made, but morphogenetic considerations are discussed briefly.
THE EFFECT OF SOME GROWTH REGULATORS ON THE VASCULAR SYSTEM OF LEMMA MINOR*
Authors: SARGENT JOHN A. , WANGERMANN ELISABETH 
Published: May 2006

SummaryWhen TIBA is added to the culture solution in which fronds of Lernna minor are growing, the vascular system of the fronds becomes more elaborate.The amount of elaboration increases with concentration up to a maximum, beyond which no further increase is obtained.TIBA must be present at an early primordial stage to be effective, and sections of pri‐mordia showed that in the presence of TIBA a greater percentage of meristematic cells becomes procambial.IAA and NAA alone cause only a slight increase in amount of vascular tissue, but added with TIBA they modify the response to TIBA in a way which bears a complex relationship to their concentration.Pre‐treatment of the fronds with IAA does not alter their response to the mixtures of IAA and TIBA.It is concluded that TIBA is not acting as an anti‐auxin, but that an unknown inhibitor of vascular tissue may be present in the fronds which is counteracted by TIBA.Other halogenated benzoic acids have similar effects.It was reported in a previous paper (Wangermann and Lacey, 1953) that the vascular system of fronds of L. minor, which is normally very simple, becomes much more elaborate when 2,3,5‐tri‐iodobenzoic acid (TIBA) is added to the culture solution, and that this effect of TIBA is modified by simultaneous addition of indole‐acetic acid (IAA). These effects have been investigated further in an attempt to gain some insight into the way in which the normal pattern is determined.
DEVELOPMENT OF THE INFLORESCENCE AND SPIKELETS OF ANTHOXANTHUM ODORATUM L.
Authors: SHARMAN B. C. 
Published: May 2006

Summary

The sequence of events in the development of the inflorescence and spikelets of Anthoxanthum odoratum is described and illustrated.
The shoot‐apex becomes longer and bears more leaf primordia during spring, becoming extremely elongated just prior to inflorescence initiation.
Primary panicle buds are borne in two rows in the axils of alternate small collar‐like leaf primordia.
These buds bear rudimentary leaf primordia in whose axils secondary buds are initiated. Similar repeated branching leads to the development of the panicle type of inflorescence.
Spikelet differentiation begins at the tip of the inflorescence and later occurs at the ends of the individual panicle branches.
The two glumes and the four lemmas arise in an orderly alternate sequence, followed by the two stamen primordia.
The stamen primordia appear to be axial in nature and are not leaf primordia.
The two stamens are probably the axillary buds of the last two lemmas.
The carpel arises on the side of the spikelet apex in the plane of the lemmas and glumes, continuing their strictly alternate sequence.
In origin the carpel appears to be homologous with a single leaf.
The two stigmas arise one on each side of the carpel as the latter encloses the spikelet tip.
In the terminal spikelet the carpel appears to be the last leaf on the whole shoot and is in strict distichous continuity with (a) the lemmas and glumes of that spikelet, (b) the collar‐like rudimentary leaf primordia subtending the primary spikelet‐branches below, and (c) the vegetative leaves at the base.
POLLEN DIAGRAMS FROM SOUTHERN ENGLAND: CRANE MOOR, HAMPSHIRE
Authors: SEAGRIEF S. C. 
Published: May 2006

SummaryPollen analyses have been made from three parts of a New Forest valley bog system, Hampshire, England. The wide valleys excavated in the preceding Full‐glacial or Late‐glacial time were shown to be filled by organic deposits accumulated rapidly during the Pre‐boreal and Boreal periods. Pinus is shown to have been strongly dominant throughout this time, and the sub‐zones a, b and c of pollen zone VI are clearly and characteristically displayed. The beech (Fagus sylvatica) is shown to have been present already in the Boreal period. These results conform with those already reported from southern England. Although at the site there is evidence of the persistence of open habitat plants of the Late‐glacial into the early Post‐glacial, thereafter the record is one of closed woodland. Deposits later than early zone VII (Atlantic) are not present.
POLLEN DIAGRAMS FROM SOUTHERN ENGLAND: ELSTEAD, SURREY
Authors: SEAGRIEF S. C. , GODWIN H. 
Published: May 2006

SummaryA small peat bog at Elstead, Surrey, has been investigated stratigraphically, by pollen analysis and by identification of macroscopic plant remains. The organic infilling was largely completed in zones IV, V and VI of the Post‐glacial period. At the close of zone III and in zone IV both pollen and macroscopic remains testify to a varied and open vegetation containing many typical Late‐glacial plants. Zone III was dominated by birch and zones IV, V and VI by pine. The sub‐zones a, b and c of zone VI are recognizable and the general picture of forest history conforms to that of other sites in the south of England, permitting a date to be placed upon the main stages of infilling of the lake‐basin, notably a phase of deposition of mineral material in sub‐zone Vic, and a possible hiatus immediately afterwards.
NEW OR RARE BRITISH GHRYSOPHYCEAE
Authors: LUND J. W. G. 
Published: May 2006

Summary Pseudokephyrion klarnetii, P. pseudospirale, P. ovum, P. ellipsoideum and an unnamed species figured by Williams (1933) are recorded and described. The records of sexuality in such algae are reviewed and the similarity between this and asexual budding considered. The taxonomic histories of Kephyrion, Pseudokephyrion, Kephyriopsis and Stenocalyx are summarized. A consideration of the characters utilized by various authors leads to the conclusion that until these algae are better known their generic limits must be uncertain. Specific limits can be clearer, particularly if sexually reproducing populations are found.
THE GENUS TAENIOMA IN WEST AFRICA
Authors: LAWSON G. W. 
Published: May 2006

SummaryThe existence of two species in the genus Taenioma is confirmed from West African material. T. nanum occurs in Sierra Leone and T. perpusillum in Ghana. In West African material of T. nanum the determinate branches invariably end in two hairs. In T. perpusillum, though the majority of determinate branches end in three hairs, two‐haired branches are quite common. They are usually, however, morphologically quite distinct from the two‐haired branches of T. nanum.
NITROGEN METABOLISM IN THE‘ROOT’OF BRASSICA NAPUS L.
Authors: BOSWELL J. G. 
Published: May 2006

SummaryThe recorded observations are interpreted on the basis that part at least of the protein in the tissue is maintained by a metabolic system in which synthesis and breakdown of protein occur simultaneously, and that these two processes are not two phases of a reversible system but are composed of two separate groups of reactions. The data obtained indicate that protein breakdown is controlled by an iron‐containing enzyme system which may well involve cytochrome and that this is associated with the Krebs cycle of organic‐acid metabolism. The synthesis of protein appears to be controlled by a copper‐containing enzyme system which in the swede ‘root’ may well involve ascorbic acid. C4 and C6 organic acids are utilized in the process of protein synthesis.
THE CASE FOR EXTENSIVE RATHER THAN INTENSIVE SAMPLING IN GENECOLOGY
Authors: HARBERD D. J. 
Published: May 2006

SummaryThis paper is primarily concerned with the technique of genecological investigation.The data refers to thirteen taxa sampled at the rate of up to five individuals per site, and in up to eighty sites, all within the Agrostis‐Festuca grassland community. Most of the fifty‐four species‐characters recorded are significantly different between populations using the within‐population variance as error, but on further investigation little of this is found to have genecological significance: it is believed to be due to genotype reduplication in sampling.Basing analyses on population means and either employing the analysis of variance of grouped data or correlation with a habitat factor, few of the characters reach significance and for the most part these characters seem to be indubitable examples of genecological differentiation. The genecological conclusions were that within the local Agrostis‐Festuca grassland the more leached sites carry the earlier populations of Cerastium vulgatum and Poa trivialis and the longer‐leaved or taller vegetative plants of Carex caryophyllea and Poa trivialis. There was some evidence in Galium spp. that apparently genecological differentiation could result from introgression.Interspecific correlation of genetical characters was investigated but no significance interpretable genecologically was found in this study. It seems likely that the species showing differentiation in the flushed to leached series of sites are differentiated in relation to different underlying environmental factors.The place of extensive methods in genecology is discussed and possible developments indicated.
THE PHYLOGENY OF MONOCOTYLEDONS*
Authors: LOWE JOYCE 
Published: May 2006

SummaryA large number of positive correlations exist among the following characters, which have been shown to be primitive for the Monocotyledons:

Perianth present
Perianth segments more than 5
Perianth homoiochlamydeous
Perianth actinomorphic
Perianth free
Hermaphrodite
Stamens 6 or more
Carpels 3 or more
Ovary inferior
Ovules many
Endosperm helobial or cellular
Ripe pollen binucleate
Ovules anatropous
Parietal cell cut off from archesporial cell
Embryo‐sac monosporic
Pollen development simultaneous
Leaves linear (uncertain)

The antitheses of these characters (perianth absent, segments fewer than 6, hetero‐chlamydeous, etc.) represent advanced conditions.Four lists of taxa were used: Engler's families, Hutchinson's families, Engler's subfamilies and Hutchinson's tribes. In general the more taxa in the list the greater the proportion of significant results. Although Hutchinson's families are fewer in number than Engler's sub‐families, they give more significant results, suggesting that Hutchinson's system is the more ‘natural’.The ‘advancement indices’of the taxa comprising the two systems are compared. Hutchinson's scheme is found to be much more uniform than Engler's regarding the range of advancement within orders and families, further indicating that Hutchinson's is more ‘natural’.The trends of evolution in the Monocotyledons show a number of similarities with those found by Sporne in the Dicotyledons. For some characters evolution in the Monocotyledons appears to have taken a course similar to the more recent of the two Dicotyledonous trends. It is suggested that this indicates the derivation of the Monocotyledons from the Dicotyledons.The taxa have been arranged according to their relative advancement (Tables 10–13). This is a contribution towards our understanding of the phylogeny of the Monocotyledons. The interconnections of the taxa, backwards through time, can however be elucidated only by increased knowledge of the fossil record.
STUDIES IN SYSTEMATIC BARK MORPHOLOGY
Authors: WHITMORE T. C. 
Published: May 2006

SummaryThe relationship between bark internal structure and surface pattern remains in general unknown.This is an investigation of the bark of 103 species of Malaysian Dipterocarpaceae. There is considerable variation between the species. Nevertheless it has been possible to induce general principles of bark construction.The bark tissues are analysed into four components. These interact and produce various features of the surface. The components are: secondary phloem, laid down at the cambium; expansion tissue, developed mainly from the phloem rays; phloem proliferation tissue, developed from the parenchyma of the conducting phloem; and periderms. The secondary phloem does not vary; the other components do and their variation is described.The bark components make up the living inner and the dead outer bark. The outer bark is acted on by external weathering processes and tangential strain to produce the fissures and ridges of the surface. The periderms and weathering processes control the sloughing of the bark and hence also its surface texture and colour.The surface pattern of the bark is a visual summation of the surface configurations, the sloughing pattern, the texture and the colour. The slash appearance (oblique tangential section through the bark) is a visual summation of the inner and outer bark.Barks are recognized in the forest from the subjective, unanalysed appearance of surface pattern and slash. These can now be analysed into objective constituent features themselves dependent on the bark tissues. This is summarized as Fig. 1.Seven distinct Bark Types are described in Dipterocarpaceae (Table 1) with major differences in the structure and interactions of the components. The Bark Types can be placed in three groups with different amounts of expansion tissue.
THE UPTAKE AND ASSIMILATION OF AMMONIA BY NEOCOSMOSPORA VASINFECTA
Authors: BUDD K. , HARLEY J. L. 
Published: May 2006

SummaryAmmonia uptake by low‐nitrogen mycelium of Neocosmospora is accompanied by an increase in the ammonia associated with the mycelium. This ammonia consists of two main fractions: the ‘exchangeable’ammonia, which is readily separated from the mycelium by cold, dilute solutions of potassium or sodium chloride, and the ‘residual’ammonia, which is retained by the mycelium under these conditions. The evidence indicates that the exchangeable ammonia represents ammonia held on exchange‐sites plus ammonia associated with a water‐space.At 25° C both fractions reach maximum levels in the mycelium within 10 minutes. The relative proportions of the exchangeable and residual ammonia depend upon conditions, especially the external pH and ammonia concentration. The maximum level attained by the residual ammonia is markedly reduced in the absence of oxygen or the presence of sodium azide of 2,4‐dinitrophenol, but none of these treatments reduces the exchangeable ammonia level. Increase in the level of residual ammonia in the cells thus appears to depend upon normal aerobic respiration but there is no evidence that this is true of exchangeable ammonia.Both exchangeable and residual ammonia decline in the mycelium during incubation in the absence of external ammonia after a period of ammonia absorption. They are therefore available for further reactions in the cell and may be normal intermediates in the synthesis of organic nitrogen compounds from external sources of ammonia.
OXALIS LA TIFOLIA KUNTH
Authors: ROBB SHEILA M. 
Published: May 2006

SummarySome morphological and anatomical aspects of the Devon and Cornwall form of Oxalis latifolia are presented, together with an account of the method by which vegetative propagation is achieved. Although distribution by seed does not appear to play a large part in disseminating the species in this country, a few capsules and seeds are recorded as having occurred in Exeter, the seeds being non‐viable. The behaviour and possible functions of the fleshy roots which develop are discussed.
THE MOVEMENT OF GROWTH REGULATORS IN PLANTS
Authors: LITTLE E. C. S. , BLACKMAN G. E. 
Published: May 2006

SummaryBy sequential visual and photographic recording, the courses of the initiation of bending and the subsequent rates of curvature of the petiole and stem have been followed when a growth regulator is applied to (a) the leaf surface above the midrib of one primary leaf, (b) a partially excised short tongue of the midrib, and (c) the cotyledonary node at the junction of a cotyledon. In a comparison of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) it was found that though the times taken to initiate bending are greatly dependent on the site of application, there are no significant differences between the two compounds. On the other hand, for indole‐3‐acetic acid (IAA), the initiation times are shorter and the equi‐effective doses are much smaller. Once bending has been initiated, for 2,4‐D and 2,4,5‐T the degree of curvature increases progressively, whereas for IAA the initial positive rate eventually becomes negative.Using 2,4‐D and 2,4,5‐T, labelled with carbon‐14 in the carboxyl group, autoradiographs demonstrated that entry into the vascular strands via the tongue of midrib take place in about 5 minutes, while for applications to the cotyledonary node radioactivity is present in the tip of the primary leaf within the same time.On the basis of these and other observations, it is concluded that under the controlled conditions selected, the initiation time for the bending of the stem following an application of either 2,4‐D or 2,4,5‐T to the leaf surface I cm from the tip can be broken down into (a) 79 minutes for enough of the auxin to pass from the leaf surface to the underlying vascular bundles, (b) 61 minutes to reach the first internode, and (c) 24 minutes to induce curvature. For IAA the corresponding figures for (b) and (c) are 31 and 17 minutes.The velocity of downward transport in the phloem is estimated at 10–12 cm/hour for 2,4‐D and 2,4,5‐T and 20–24 cm/hour for IAA. From differences in the initiation times for applications of 2,4‐D to the tip and base of the leaf the velocity was estimated to be 14–25 cm/hour.Simultaneously with observations on the course of bending, the amounts of [14C]2,4‐D and [14C]2,4,5‐T. present in the tissues were followed. When bending is initiated the petiole and first internode contain 0.0016 and 0.008 μg respectively.The distribution of 2,4‐D applied to one of the primary leaves was examined for periods up to 27 hours. Penetration into the leaf and subsequent export from the leaf are greatest when the application is made to the tongue of midrib, less for an application to the lower leaf surface and least for the upper surface. The pattern of accumulation is dependent on the amount exported. In general, accumulation is highest in the first internode and upper hypocotyl. At the end of 27 hours no 2,4‐D is yet present in the opposite leaf.
AGEING IN ROOTS OF GROUNDSEL (SENECIO VULGARIS L.)
Authors: WREN M. J. , HANNAY J. W. 
Published: May 2006

SummaryObservations have been made on the root system of groundsel seedlings cultured aseptically in darkness, in media containing sucrose and vitamins. Root development followed a definite pattern, in which loss of meristematic activity occurred first in the primary root and later in the lateral roots.Varying the sucrose concentration of the culture medium modified growth rates considerably but did not change the basic pattern of development. Growth rates were highest, initially, in media containing 4–6 % sucrose but these roots ceased growth much earlier than those in i % and 2 % sucrose. Addition of 2‐naphthoxyacetic acid to initially sub‐optimal sucrose media stimulated growth but also accelerated the ‘death’of the root apex. On the contrary, i‐naphthoxyacetic acid prolonged meristematic activity in high sugar media, resulting in healthy root systems in which the radicle retained its apical dominance.A comparison of the behaviour of seedling roots and excised roots suggests that the pattern of root development in the seedling was controlled by an ageing process similar to that previously observed in excised roots. Discrepancies between the two materials may be attributed to an ‘anti‐ageing’effect of the shoot.