bluuebunny/crossref_metadata_2025 huggingface dataset:
THE PHYLOGENY OF MONOCOTYLEDONS*
Authors: LOWE JOYCE
Published: May 2006

Summary

A 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

Summary

The 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

Summary

Ammonia 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

Summary

Some 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

Summary

By 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

Summary

Observations 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.
STUDIES IN POTENTILLA L.
Authors: SMITH GORDON L.
Published: May 2006

Summary

Field populations of Potentilla crantzii in the British Isles are often remarkably uniform morphologically within themselves. Purely vegetative spread seems to be very restricted, and populations consist of discrete individuals, presumably established from seed. The mechanisms involved in reproduction by seed have been investigated in three Scottish topodemes. Crosses between P. crantzii as female parent and P. tabernaemontani, P. arenaria and P. aurea as pollen plants yielded progenies which were quite uniform and which resembled P. crantzii morphologically. The mechanism of maternal inheritance in representatives of these topodemes has been elucidated cytologically. Plants from Ben Lawers and Inchnadamph differed significantly in their embryology from P. tabernaemontani previously investigated. Female meiosis was observed in all stages, but the products degenerated without exception and unreduced embryo sacs arose by diplospory. In the third topodeme from Creag an Dail, there was no sign of meiosis beyond the synapsis stage and embryo‐sacs were aposporous in origin. No plants produced seed without prior pollination. Although, in emasculated flowers, the autonomous division of the egg cell formed embryos, endosperm was always lacking. The continued development of embryos is dependent on endosperm and consequently no mature seed is produced. One chromosome count in endosperm after pollination suggests that endosperm formation is the result of a genuine fertilization rather than merely stimulation by the pollen.
AMINO‐ACID METABOLISM IN GERMINATING SEEDS OF VICIA FABA L. IN RELATION TO THEIR BIOLOGY
Authors: BOULTER D. , BARBER J. T.
Published: May 2006

Summary

Seeds of Vicia faba L. were grown without an external nitrogen supply and the amount of nitrogen in free amino acids, protein amino acids and other soluble nitrogenous compounds determined in the various tissues of ungerminated, 6‐ and 14‐day‐old material.

It was found that, on germination, the reserve proteins of the beans were hydrolysed to give at least some free amino acids which were then interconverted and used in the synthesis of new compounds. Glutamine was not formed extensively until after 6 days of growth and the synthesis of this amino acid may be related to the prior onset of photosynthesis which might supply necessary carbon precursors.

The proteins of the ungerminated beans were shown to contain a high proportion of nitrogen in basic and dicarboxylic amino acids and during germination major changes occurred during which all these amino acids decreased in amount. Arginine played an important part in the metabolism of the seedlings and the results of preliminary 14C feeding experiments indicate that it may be degraded by a reversal of the ornithine cycle. The decrease in the amount of arginine, other basic amino acids and the dicarboxylic amino acids are discussed in terms of their metabolism and utilization as intermediates in the synthesis of proteins and other nitrogen constituents necessary for the establishment of autotrophic nutrition.
STRUCTURE AND SEASONAL STUDY OF THE SHOOT APEX OF SOME CUPRESSUS SPECIES
Authors: PILLAI S. K.
Published: May 2006

Summary

The shoot apices of three species of Cupressus exhibit four zones; the superficial layer, the sub‐apical initials, pith mother cells, and the flanking zone. The superficial layer can be subdivided into the apical initials which contribute by periclinal divisions to the subapical initials below and by anticlinal ones to the surface layer on the flanks. Thus the apical initials form the ultimate source of all the cells of the shoot apex in these species.

The subapical initials are composed of a very limited number of cells, and may even be only one cell deep in some apices. The initials give rise to the flanking zone laterally and pith mother cells proximally.

The flanking zone exhibits a stratified pattern and is composed of more or less uniform and densely staining cells. The pith mother cells form a very shallow zone. A pith rib‐meristem is absent and the cells mature abruptly into pith cells.

During the less active months the apical initials do not exhibit periclinal divisions and hence appear like a tunica. But there is no period of dormancy in the shoot apex of C. sempervirens, of which a seasonal study was made.
THE UPTAKE OF PHOSPHATE BY EXCISED MYCORRHIZAL ROOTS OF THE BEECH
Authors: HARLEY J. L. , LOUGHMAN B. C.
Published: May 2006

Summary

Phosphate absorbed from KH232PO4 solutions of low concentration by beech mycorrhizas is rapidly esterified. After periods of a few minutes about one‐half of that absorbed is found in organic compounds. Both fungal and host tissues when exposed, after separation, to radioactive phosphate solutions show this ability for rapid esterification. Whole mycorrhizas which had been allowed to absorb KH232PO4 were rapidly dissected in the cold and the labelled phosphate fractions in their host and fungal tissues were separated. In the host tissue 90 % of the 32P was found in inorganic phosphate after half a minute and this percentage fell to a little under 80 % after 10 minutes. The curve of percentage labelling of inorganic phosphate in the host tissue appeared to extrapolate to 100% at zero time. It is concluded that inorganic phosphate passes into the host from the fungus. This result is discussed in relation to previous work on phosphate absorption by mycorrhizas.
FURTHER OBSERVATIONS ON AESTIVATION IN RANUNCULUS REPENS L.
Authors: CUNNELL G. J.
Published: May 2006

Summary

Large samples of mature flower buds of Ranunculus repens L., from three different positions on the inflorescence, were collected at two localities near London during the early summer of 1959. From each of the six collections 320 normal flower buds were dissected, 160 with a right quincuncial calyx and 160 with a left quincuncial calyx, and the aestivation of the corollas recorded.

Although the corolla aestivation is very variable and all thirty‐two possible arrangements are found in each sample the petal overlaps are not randomly distributed and can be related to the two calyx types. The analysis provides evidence that the aestivation pattern differs with position of the flowers on the inflorescence and that for samples of flowers from any one position on the inflorescence the pattern is similar from site to site and from year to year.

Comparison is made with other published work on variable, imbricate pentamerous corollas and the significance of the observations is briefly discussed.
THE EFFECT OF DINITROPHENOL AND OTHER INHIBITORS ON THE UPTAKE AND METABOLISM OF 2,4‐DICHLOROPHENOXYACETIC ACID BY CHLORELLA
Authors: SWETS W. A. , WEDDING R. T.
Published: May 2006

Summary

The uptake of 2,4‐D by Chlorella into a non‐diffusible, non‐exchangeable form as influenced by various inhibitors, substrates and environmental factors has been studied. Those factors which tend to increase the rate of glycolysis or to reduce the activity of the TCA cycle result in an increased uptake of 2,4‐D. The addition of exogenous acetate or aspartate also causes an increase in the amount of 2,4‐D retained in the cell.

The influence of DNP on 2,4‐D uptake has been given especial attention. Increasing concentrations of this inhibitor at first cause a progressive inhibition of 2,4‐D uptake, which at higher concentrations, is reversed by a substantial stimulation.

The data presented are discussed in relation to the hypothesis that the first reaction undergone by 2,4‐D in the cell is one in which acetyl CoA participates. The participation of aspartate in the metabolic process appears to follow that of acetyl CoA and may result in the formation of an aspartyl‐2,4‐D complex.
STUDIES ON THE GERMINATION AND MOISTURE RELATIONSHIPS OF SUGARCANE SETTS
Authors: PANJE R. R. , RAO T. RAJA
Published: May 2006

Summary

Studies were undertaken to elucidate the moisture relationships in germinating sugarcane setts* and the precise role of moisture in the early stages of germination.

It was found that when the controlling effect of the apical meristem was removed by cutting the cane into individual, single‐budded setts, the water in the cane moved into the bud. It appeared that the meristemic cells of the bud (and root primordia) must attain a certain critical water content before they can start to sprout.

Increasing the water content of setts increased the moisture in the bud and root primordia until they attained the critical level, when sprouting was hastened. Bud and root primordia appeared to compete for water in the sett. Removal of buds hastened the sprouting of root primordia. When the water content of setts was increased the inhibiting influence of buds on the sprouting of root primordia was nullified.

At 96% relative humidity both buds and root primordia sprouted and grew out, but at 85% relative humidity, buds sprouted but root primordia did not. This disparity in the sprouting condition of buds and root primordia appeared to be due to the protective action of the bud‐scales. When the water content of the setts was increased both the buds and root primordia sprouted, but the latter dried up shortly thereafter.

Experiments showed that the water in a sett was adequate for the germination of its buds and that, in the early stages, the role of soil water was only indirect.
SOME EVIDENCE OF POPULATION DIFFERENTIATION IN RUBUS IDAEUS L.
Authors: JENNINGS D. L.
Published: May 2006

Summary

Plants of Rubus idaeus were collected from habitats of contrasting altitudes in Scotland and grown in Dundee. Subsequent observations suggested the presence of population differentiation in respect of time of bud‐burst and plant height, plants from more exposed situations being later to start growth in the spring and producing shorter canes with shorter internodes. The results are discussed in relation to the breeding system and physiological responses of the plants.
THE ISCA GRAIN, A ROMAN PLANT INTRODUCTION IN BRITAIN
Authors: HELBAEK H.
Published: May 2006

Summary

Debris surrounding a deposit of carbonized grain found at the Roman fortress of Isca, Caerleon, Wales, was examined and various cereals, grasses and weeds identified. The find provides evidence of weed introductions new to Britain and of the use of cereals in brewing.
POLLEN DIAGRAMS FROM DARTMOOR
Authors: SIMMONS I. G.
Published: May 2006

Summary

A Seires of pollen diagrams from upland Dartmoor are presented. They cover the Post‐glacial period from early zone IV to the present day but the Late‐glacial is not represented.

The extension of forest cover over the region is deduced and an early, pre‐Ulmus decline of forest is noted, preceding more widespread clearance in zones VIIb and VIII The immigration of Alnus is deduced to be more rapid when biotic influences are present. The composition of the past forest is discussed in the light of the present distribution of Quercus spp. In the region and the probable, local presence of Fagus is postulated in zone VIIB and later. The parallelism of the Plantago and Fagus curves lends support to Godwin's suggestion that the immigration of Fagus is bound up with the movements of prehistoric man.
PROTOPLAST STRUCTURE IN SIEVE TUBE ELEMENTS
Authors: THAINE R.
Published: May 2006

Summary

The microscopic structure of sieve tube elements was studied in fresh hand sections from Cucurbita pepo, Glycine max and Solanum tuberosum. The sections were stained in aqueous solutions of either iodine (Lugol's) or eosin. Photomicrographs from these preparations show linear cytoplasmic structures attached to sieve plates, and linear files of particles associated with cytoplasmic strands. In addition, phase contrast observations of fresh Cucurbita pepo phloem exudate revealed cytoplasm constituents including membranes, fibrillar elements, 0. 1–0.2 μ in diameter, and mitochondria‐like particles floating free, or associated with the fibrillar elements. Plastids, 5 μ in diameter, also occurred in the fluid exudate, sometimes associated with the aggregates of structural material. Cytoplasmic structures in sieve tube elements and in fresh phloem exudate are interpreted as the remains of damaged transcellular strands.

In the transcellular streaming concept of phloem transport, transcellular strands are an essential part of the sieve tube element, and present evidence leaves little doubt that these structures really exist.
A CONTRIBUTION TOWARDS UNDERSTANDING OF ‘THE PRIMITIVE FUCOID’
Authors: MANTON I.
Published: May 2006

Summary

The spermatozoids of three genera of Cystoseiraceae (Halidrys, Cystoseira and Bifurcaria) have been investigated electron microscopically with respect to their external morphology, and two of them (Cystoseira and Halidrys) also with respect to their microanatomy for the purpose of comparison with Fucus on the one hand and a brown algal zoospore on the other. Special attention has been devoted to the flagellar ‘root’ which is shown to be the homologue of the proboscis of Fucus and to be present also in the zoospore of Scytosiphon. Comparison between Scytosiphon, Dictyota and the Fucoids suggests that the true function of the flagellar root is not mechanical but metabolic or conductional, perhaps in some relation to respiration or gaseous exchange. The evidence is interpreted as giving strong support to the view that Fucus is not primitive but highly specialized and that Cystoseira has remained closer to an ancestral condition in a number of different characters.
THE TAXONOMIC SIGNIFICANCE OF CERTAIN ANATOMICAL OBSERVATIONS ON ERICACEAE
Authors: WATSON L.
Published: May 2006

Summary

A review of the classical treatment of Ericaceae reveals how unconvincing are the usual definitions of the major groupings Ericoideae and Arbutoideae. However, a survey of stomatal structure, stomatal distribution and pith structure supports the taxonomic soundness of the main body of the Ericoideae, which are further characterized by their distinctive habit. Calluna is exceptional among Ericoideae in pith structure and stomatal distribution, and differs from the others in various aspects of gross morphology. There is a striking similarity between Calluna and Cassiope, a genus usually placed in the Arbutoideae; and there is little doubt that the two are closely related. These conclusions lead to speculation about the origin and development of the Ericoideae in the minds of taxonomists, and about the mechanism by which closely similar genera become separated at the level of sub‐family.
AN EMBRYOLOGICAL STUDY OF SALOMONIA CANTONIENSIS LOUR
Authors: RAO A. N.
Published: May 2006

Summary

The flower development, structure and different aspects of embryology of Salomonia cantonien‐sis are described. Development of the floral parts occurs in acropetal succession. The wall of the anther is composed of three layers of cells. The tapetum is of secretory type with binucleate cells. The endothecial layer develops fibrous thickenings and with the epidermis forms the mature anther wall. The pollen grains are polycolporate, three‐celled at the time of shedding and the majority of them germinate in situ. The ovary is superior and bilocular with a single anatropous bitegmic ovule in each locule. The embryo‐sac develops according to the Polygonum type. The flowers are autogamous and the process of pollination is described. The endosperm is free nuclear to begin with but later becomes cellular. The embryo development follows the Asterad type as in other members of Polygalaceae. Most of the endosperm is used up by the growing embryo. The two‐layered seed‐coat is organized by the outer integument of the ovule. The present observations are discussed with other relevant literature.
A NEW TYPE OF APOGAMY IN FERNS
Authors: BRAITHWAITE A. F.
Published: May 2006

Summary

Studies on apogamous members of the Asplenium aeihiopicum complex in Africa have shown a marked departure of cytological behaviour from that previously known in apogamous ferns. The sporangial development is characterized by all sporangia producing sixteen spore mother cells each showing complete asynapsis at diakinesis with either 288 or 330–357 chromosomes. The first meiotic division ends in a restitution nucleus which then divides regularly to produce diads of diplospores. This abbreviated meiosis is compared with the cytological phenomena accompanying apogamy in other ferns and with a similar division process known from apomictic Angiosperms. Evidence is presented from the literature which indicates that a similar abbreviated meiosis may accompany apogamy in the Hymenophyllaceae. Little new evidence on either the causal aspect of apogamy or the possible origin of the apogamous forms within the A. aethiopicum complex can be adduced at present.
THE EFFECT OF CATIONS ON THE ABSORPTION OF PHOSPHATE BY BEECH MYCORRHIZAL ROOTS
Authors: JENNINGS D. H.
Published: May 2006

Summary

Pretreatment of beech mycorrhizal roots with relatively high concentrations (10−2 M to 10−1 M) of ammonium, potassium and sodium salts can cause a reduced uptake of radioactivity from phosphate solutions containing 32P. These same salts also decrease the ability of the roots to retain radioactivity already absorbed—the greatest losses occurring at low temperatures. Radioactive phosphorus both in orthophosphate and bound form is lost. Calcium ions have no effect on the absorption of radioactivity but can nullify the effect of the monovalent ions both on the absorption and loss of radioactivity. The results are discussed in relation to other work on cell permeability. It is concluded that the monovalent cations increase a non‐specific efflux of phosphate compounds from the roots which is little affected by metabolism but which can be inhibited by calcium ions. It is also pointed out that these results have important implications with respect to a kinetic analysis of phosphate absorption from solutions of varying strength of a phosphate salt of a monovalent cation. There is evidence that monovalent cations will have a similar effect on phosphate uptake by non‐mycorrhizal tissues.
THE PRE‐PEAT VEGETATION OF THE SOUTHERN PENNINES
Authors: TALLIS J. H.
Published: May 2006

Summary

Pollen counts from the upper layers of the mineral soil underlying deep blanket peat at two sites in the southern Pennines show a varied assemblage of Late‐glacial and montane species such as Armeria maritima, Thalictnim, Juniperus, and possibly Betula nana, existing in zone VI at 550–610 m. This ‘montane’ flora disappears where the pollen spectrum indicates waterlogging of the soil developing as a result of the increased wetness of climate. Peat formation at these two sites appears to begin at the B.A.T., but pollen counts from other sites in the southern Pennines show that peat may have begun to form elsewhere at any time during zone VIIa, depending on local topography. Corylus pollen values show a pronounced maximum at the close of zone VI, and it is suggested that extensive hazel thickets may have formed in sheltered gullies and valley heads; at one of the two sites very high values of fern spores are also encountered in the uppermost layers of mineral soil. The abrupt decline in the fern spore values and equally abrupt changes in values of other pollen types at the level of the peat‐mineral soil junction suggest that there may possibly be a gap in the pollen record at the end of zone VI, resulting from local soil erosion.
TWO FOSSIL DIATOMS FROM THE LAKE DEPOSITS OF THE ENGLISH LAKE DISTRICT
Authors: EVANS G. H.
Published: May 2006

Summary

Melosira distant var. blelhamensis n. var. is described. This has only been found in Post‐glacial deposits. The hitherto uncertain identity of a large Melosira, common in the Late‐glacial and early Post‐glacial lake deposits of the English Lake District, is discussed and it is suggested that its correct name is M. teres Brun.
SECONDARY CORTEX IN THE ARBORESCENT LYCOPODS
Authors: SMITH D. L.
Published: May 2006

Summary

Early stages in the development of the secondary cortex in stems of Lepidophloios kilpatrickensis indicate that the tissue originated as a meristematic zone three cells wide. Each cell of the zone underwent periclinal division to form a radial file of cells. It is suggested that in the mature secondary cortex each complete radial file represents the derivatives of three initial cells and that short files represent the derivatives of one, or two, initials.
PLANT GROWTH AND THE AERIAL ENVIRONMENT
Authors: HUGHES A. P.
Published: May 2006

Summary

Plants were established for 17–23 days in lights of 17–19 cal/cm2/day (≡ 10% summer daylight) using 16 hours fluorescent light in controlled environment cabinets and were then transferred to lower light intensities in the range 1.5–8.7 cal/cm2/day (≡ 0.9–5% summer daylight). The unit leaf rate was linearly related to light intensity over the range 0–20 cal/cm2/day and the compensation point was approximately 0.3 cal/cm2/day. The changes in unit leaf rate were closely followed by marked morphogenetic changes, even in plants growing in light intensities so low that there was scarcely any net gain in weight. Over the dry weight range 6–35 mg low light intensity did not evoke a great increase in leaf area ratio as, over this range in size, the principle cause of increased leafiness was the increase in leaf weight ratio, which is scarcely affected by light intensity. Plants of greater than 35 mg dry weight showed the strong reciprocal relationship between unit leaf rate and leaf area ratio due to the effect on specific leaf area. At very low light intensities the increase in leaf area ratio was not adequate to offset the fall in specific leaf area and the relative growth rate was diminished sharply over the light range from 15 cal/cm2/day to the compensation point for light. The significance of these physiological features for the aut‐Ecology of Impatiens parviflora is discussed.
THE RESPIRATION CLIMACTERIC IN APPLE FRUITS
Authors: JONES J. D. , HULME A. C. , WOOLTORTON L. S. C.
Published: May 2006

Summary

The activities of various mitochondrial enzymes in the peel of apples picked before the climacteric peak in respiration (R), were followed throughout the development of the climacteric in storage at 12°C they showed an increase to the climacteric peak and beyond. In pulp tissue the peak values for mitochondrial activity occurred several days before the peak value of R. The soluble enzyme, malic enzyme (M.E.), reached a maximum in both peel and pulp at a point very close to the maximum value of R, while pyruvic carboxylase continued to rise past the climacteric peak.

In fruit picked during the development of the climacteric on the tree and stored at 12°C, mitochondrial activity tended to follow changes in R; in the pulp a falling rate of mitochondrial activity probably commenced somewhat before the commencement of a fall in R. M.E. activity increased rapidly on picking in the early stages of the climacteric but little further increase occurred either in peel or pulp when fruit was picked near the point of maximum activity on the tree. This maximum activity on the tree was reached well before the peak in R and corresponded in time with the maximum rate of R ever reached in detached fruit.

It is concluded that an increase in activity of M.E. and carboxylase is largely responsible for the climacteric rise in R up to the maximum rate attained in detached fruit, and that the excess respiration above this value ‘on’ the tree stems from other sources.
CARBOHYDRATE PHYSIOLOGY OF MYCORRHIZAL ROOTS OF BEECH
Authors: LEWIS D. H. , HARLEY J. L.
Published: May 2006

Summary

Mycorrhizal roots of beech absorb [14C]glucose, fructose and sucrose at rates some two and a half times faster than uninfected roots. In the latter, sucrose is synthesized from all three sugars despite the presence of an active surface invertase, clearly suggesting that uptake from sucrose involves prior hydrolysis. There is only a small incorporation into polysaccharides by uninfected roots, this being into structural polymers. In contrast, mycorrhizal roots synthesize principally trehalose and glycogen from glucose, and mannitol from fructose. Sucrose feeding results in synthesis of all three storage carbohydrates. Whatever sugar is supplied to mycorrhizas, host sugars incorporate little radioactivity and dissection shows that 70% of the activity, following long term glucose feeding, remains in the sheath and, of the 30% in the core, most is in fungal metabolites of the Hartig net. When fed separately, core tissue more closely resembles the behaviour of uninfected roots.

From the totally different destinations of the two hexoses in mycorrhizas, it is concluded that the fungus, unlike host tissue, has a restricted ability to interconvert hexoses. From experiments with high specific activity [14C]glucose supplied to mycorrhizas in tracer quantities, it appears that alternative pathways of carbohydrate breakdown such as the pentose phosphate cycle and Entner‐Doudoroff scheme may possibly be operative in addition to glycolysis and so supplement the breakdown of sugars to the level of pyruvate.
LATE‐GLACIAL DEPOSITS AT BAGMERE, CHESHIRE, AND CHAT MOSS, LANCASHIRE
Authors: BIRKS H. J. B.
Published: May 2006

Summary

Investigations of deposits at the two sites disclose basal stratigraphic sequences characteristic of the Late‐glacial Period of north‐west Europe. The pollen analyses presented confirm that the deposits represent the Late‐glacial Period and extend into the early Post‐glacial. (The periods, which are described as Late‐glacial and Post‐glacial to conform with previous usage (Godwin, 1956) correspond to the Late‐Weichselian and Flandrian stages, respectively (West, 1963).) The low frequency of arboreal pollen during the Late‐glacial at both sites is a feature common to many sites in Western Britain. Amongst the plants recorded Cryptogramma crispa, Gentiana pneumonanthe, Saussurea alpina, Dicranum elongatum and D. spurium are the most notable.
ANATOMY AND THE TAXONOMIC SIGNIFICANCE OF GROSS VEGETATIVE MORPHOLOGY IN SENECIO
Authors: DRURY D. G. , WATSON L.
Published: May 2006

Summary

The well‐known arrangements of Senecio species appear to be based on inadequate data. Observations on leaf hairs, achene hairs, corolla venation, pappus structure and ovarian crystal form are presented for forty‐five species. A classification based on these features bears little resemblance to the conventional view of the genus, but its taxonomic soundness is strikingly supported by considerations of gross leaf morphology and habit.
CONTROLLED ENVIRONMENT STUDIES OF THE NATURE AND ORIGINS OF WATER DEFICITS IN PLANTS
Authors: MACKLON A. E. S. , WEATHERLEY P. E.
Published: May 2006

Depression of water potential. δW (d.p.d.), in the leaves, transpiration and stomatal aperture were measured on Ricinus communis plants subjected to controlled levels of atmospheric evaporation in a climatological wind tunnel.

It was found that the leaf δW of transpiring plants rooted in water took up a value of about 5 atm and remained unaffected by large changes in transpirational flux. When water was replaced by an osmoticum round the roots, leaf δW merely rose to approach the δW of the medium. These results indicate that root resistance plays little part in determining levels of leaf δW above 5 atm.

However, an increase of transpiration rate led to a rise in the δW of the leaves in plants rooted in soil, and when the transpiration rate was lowered again leaf δW fell to near its original level. These results are interpreted on the hypothesis that the source of water deficits in plants lies primarily in the soil and not in the resistance to water flux offered by the roots. During a period of high transpiration, soil adjacent to the roots dries out due to the low water conductivity of the soil and this is reflected in a rise in δW in the leaves. Recovery of leaf δW occurs only when transpiration becomes low enough for the rate of water supply to the root zone to exceed the rate of absorption by the plant.

This hypothesis is supported by preliminary measurements of soil δW. During a period of rapid transpiration the soil δW in the root zone rose above that in the surrounding root‐free soil. On a return to low transpiration conditions the soil δW in the root zone fell to the level of the surrounding soil again.
QUIESCENT CENTRE OF THE PRIMARY ROOT OF GLYCINE MAX
Authors: MIKSCHE J. P. , GREENWOOD M.
Published: May 2006

Summary

The quiescent centre of Glycine max was observed to change in size at various times after sowing. It increases in size during early development, then decreases with a corresponding reduction of the cell population of the root. Delimitation of quiescent centre boundaries is difficult in view of dramatic changes in size of regions of non‐DNA synthesis within the primary root.
STUDIES IN THE LENTIBULARIACEAE
Authors: FAROOQ MOHD , SIDDIQUI SAEED A.
Published: May 2006

Summary

The development of endosperm in Utricularia vulgaris var. americana conforms to the Scutellaria type of Schnarf (1917). Binucleate micropylar and chalazal endosperm haustoria are present. An accessory haustorial cell may differentiate adjacent to the chalazal haustorium. Sometimes the micropylar haustorium may be trinucleate. Occasionally the development of endosperm takes place by transverse divisions. In such cases the chalazal haustorium is usually uninucleate and the entire micropylar endosperm chamber differentiates as the micropylar haustorium.
STUDIES OF THE BALLISTICS OF ASCOSPORES
Authors: WALKEY D. G. A. , HARVEY R.
Published: May 2006

Summary

The ballistics of horizontal spore discharge in fifteen species and two varieties of Ascomycetes have been studied. An apparatus for measuring horizontal discharge is described and formulae derived for the volumes of irregularly shaped spores. The average and maximum distances of discharge for the selected fungi are recorded and include maximum ranges of more than 50 cm for Podospora fimiseda and the 64‐spore variety of P. decipiens.

An analysis of the relationship between the average distance of horizontal discharge and projectile size shows that the formula d=Kr2 does not hold true for comparisons between a large number of unrelated species. If, however, only closely related species, such as those of the genera Podospora and Sordaria, are considered then considerable agreement with the formula is observed.

If, in a single species, the relationship between size and distance of discharge of various sizes of spore‐projectiles is analysed, the results are in accordance with the formula d = Kr2 only if there is relatively high separation of the full spore complement into projectiles of different sizes. It is suggested that deviation from the formula occurs because the initial velocity of discharge is not constant for all projectiles.
ANALYTICAL STUDIES OF THE GROWTH OF THE ETIOLATED SEEDLING OF AVENA SATIVA
Authors: CAUSTON D. R. , MER C. L.
Published: May 2006

Summary

Observations have been made of cell numbers per column and the distribution of the cell length along the mesocotyl. Mathematical expressions are then derived from the calculated curves of best fit for the rate of cell production and for the mean cell length in the first millimetre of the mesocotyl below the coleoptilar node. Further expressions are deduced for mean cell length in the meristem, for the total length of the meristem, and for the number of meristematic cells present in a single column. It is now possible to describe accurately the activity of the mesocotyl meristem in the untreated plant, and so determine the effects of carbon dioxide.

Considering the entire meristem, the effect of carbon dioxide is to prolong and slightly enhance cell production. This comes about through a delay in elongation of the vacuolating dividing cells. In addition carbon dioxide appears to depress slightly the potential level of mitotic activity’ of a cell of a given length or age, but this effect is more than made up for by the increase in the number of dividing cells present.
THE ABSORPTION AND TRANSLOCATION OF PHOSPHORUS BY SEEDLINGS OF HORDEUM VULGARE (L)
Authors: CROSSETT R. N. , LOUGHMAN B. C.
Published: May 2006

Summary

Measurements were made of the absorption of 32P and its movement into the shoots of barley seedhngs growmg in millimolar phosphate nutrient solutions. The rate of movement of 32P into the shoot increased during the first 4–6 hours of absorption but thereafter remained constant. When an identical inactive nutrient solution was substituted for one labelled with 32P movement of radioactivity into the shoot continued for only 4–6 hours, the amount moving being independent of the length of the preceding absorption period and hence the amount of 32P in the root. The kinetics of 32P movement following such a change were examined.

32P was applied to the tips of roots growing in inactive nutrient solutions and radioactivity measured along the length of the root. An analysis was made of the chemical compounds in which 32P was found and a rough estimate made of their turnover rates.

It was concluded that 32P entering the root is either accumulated in it, as orthophosphate, or mixes with a small part, called the root pool, of the phosphorus in the root before moving into the shoot. It wa suggested that the pool lies outside the outside the vascular system and that the acid‐soluble organic phosphorus compounds of the root are in dynamic equihbrium with it.
A CHAMBER SUITABLE FOR MEASUREMENTS OF GAS EXCHANGE BY LEAVES UNDER CONTROLLED CONDITIONS
Authors: HARDWICK K. , LUMB H. , WOOLHOUSE H. W.
Published: May 2006

Summary

Details are given of the design and construction of a leaf chamber and gas circuit suitable for the measurement of the carbon dioxide exchange and rate of transpiration from intact leaves under controlled environmental conditions.
CHEMO‐ORGANOTROPHIC GROWTH OF XANTHOPHYCEAN ALGAE
Authors: CASSELTON P. J.
Published: May 2006

Summary

A number of algae were tested for their ability to grow in the dark when supplied various organic substrates. Glucose was utilized by Chloridella neglecta, Botrydiopsis arhiza, Chloro‐closter solani, Bumilleriopsis peterseniana and Heterococcus caespitosus but not by ViscJieria stellata and Pleurochloris commutata. Chloridella neglecta was also able to utilize galactose and Chlorocloster solani galactose, mannose and fructose. The utilization of maltose, sucrose, xylose, ribose, mannitol, acetic acid, citric acid, succinic acid and lactic acid by any of the algae was not detected.

Chromatographic separation of the pigments of the algae suggested that all were members of the Xanthophyceae with the exception of C. solani. It is suggested that C. solani is a member of the Chlorophyceae since chlorophylls a and b were detected.

An apparendy greater growth in the dark by C. solani utilizing fructose rather than glucose was attributed to a differential change in pH of the medium containing the sugars during autoclaving.
MORPHOLOGY OF THE FERTILE LEAVES OF THE LOMARIOPSIDACEAE, WITH SPECIAL REFERENCE TO THE VENATION
Authors: NAYAR B. K.
Published: May 2006

Summary

Fertile pinnae of thirty‐one species of the eight genera of Lomariopsidaceae studied have the lamina variously reduced, in some cases to narrow wings on either side of the midrib. The lamina is either broad, thin, and with the venation conspicuous on the surface, or narrow, fleshy, and with hidden venation. The mesophyll is undifferentiated and consists of thin‐walled parenchyma which possesses collapsible walls in some species. Intercellular air spaces are inconspicuous in most species. The epidermal cells are usually thin‐walled, chlorophyllous and dorsiventrally flattened. The midrib has two or three vascular strands which unite into one in the anterior half of the lamina. Distinct sclerenchyma tissue is absent: a few layers of thick‐walled hypodermal cells occur in the midrib region in some.

Venation of the fertile pinna is almost similar to that of the sterile pinnae in Bolbitis and Lomagramma (both reticulate), and in Egenolfia, Elaphoglossum and Thysanosoria (all free‐veined). The fertile pinnae of Arthrobotrya, Lomariopsis and Teratophyllum usually possess a reticulate venation, though the sterile pinnae are free‐veined. A set of special veins supplying the sporangia is found in addition to the ‘normal’ venation in many species except Elaphoglossum and Thysanosoria. The special venation is variously developed in the different species of each genus; it consists of a set of veins close to the lower epidermis of the lamina and connected to the ‘normal’ veins at intervals: in some cases the special veins form extensive reticulations independent of the ‘normal’ venation. The two sets of veins are at different planes, one above the other. The special venation is not connected directly to the midrib and often has a longitudinal vein running parallel to the midrib on either side.

In all genera, except Thysanosoria which has discrete sori restricted to the vein tips, sporangia are acrostichoid in distribution. They are of the common leptosporangiate type. The sporangial stalk is slender and long in all, except Lomagramma and Lomariopsis in which it is short and stout. The stalk is three cells thick, the third row developed secondarily as a protrusion of the basal wall cell of the capsule in continuation of the stomium. Distinct paraphyses are absent, except in Arthrobotrya, Lomagramma and Teratophyllum.

The spores are bilateral, monolete and ranging in size from 22 × 33 μ(Bolbitis spp., Elaphoglossum spp.) to 90 × 125 μ(Lomariopsis intermedia). The exine is smooth except in Lomagramma, Thysanosoria (both granulose) and Lomariopsis spp. (spinulose). Lomagramma and Thysanosoria are perine‐less; all others are perinate, with the perine bearing characteristic reticulate ornamentation in all except Bolbitis and Elaphoglossum.