Ontogenic change in leaf shape and crown form of a tropical tree,Scaphium macropodum (Sterculiaceae) in Borneo

Crown architecture was analyzed forScaphium macropodum (Sterculiaceae), a common shade-tolerant emergent tree of a tropical rain forest in West Kalimantan, Indonesia. Saplings and poles shorter than 12 m in height had no branches, and gathered their leaves at the ends of the stem. The leaves changed from entire to palmately-parted with increasing tree size. The parted leaves increased the light penetration through the clustered foliage. The size of leaves including the blade and petiole ranged from 22 cm to 147 cm. Because the weight of petiole per blade increased with leaf size, the leaf could not be enlarged infinitely. Taller trees with lateral branches bore small (about 40 cm in length) entire leaves. The light intensity in the forest increased from the ground to about 12 m tall and was nearly constant from 12 m to 18 m. Crown architecture ofS. macropodum adapted to this light environment. The monoaxial trees lower than 12 m could thus increase the amount of light with vertical elongation, and the branched trees higher than 12 m could increase it by means of lateral extension of crown area.     

Isolation of endophytes from leaves of <Emphasis Type="Italic">Neolitsea sericea</Emphasis> in broadleaf and conifer stands

Endophytic fungi were isolated from leaves of Neolitsea sericea, a major lauraceous tree in the laurel forests of southern Kyushu, collected from the understory layer of broadleaf and conifer stands. Cytosphaera sp. and a species of Ascomycetes in leaf blade segments, plus a xylariaceous species and Phomopsis spp. in petiole segments, were isolated at relatively high frequency. In general, isolation frequencies of endophytes were higher in petiole than blade segments. In blade segments, patterns of endophyte isolation were quite different among stands, while relatively similar in petiole segments. Significant effects of sampling sites or canopy vegetation were rarely detected. the understory layer of laurel forests. Neolitsea sericea is an evergreen broadleaf lauraceous tree, widely distributed in areas of eastern Asia. In southern Kyushu, it is one of the most common trees, growing both as canopy and understory species. In this study, endophytes were isolated from the leaves of N. sericea growing in the understory layer of conifer and broadleaf forest stands to survey the endophytes of N. sericea leaves and to examine the effect of the canopy layer on endophytic mycobiota in understory plants.     

Food selection by western gorillas (G.g. gorilla) in relation to food chemistry

Summary Samples of stems, leaves, shoots and fruit (N=36) from lowland, African rain forest are analyzed for nutrients, digestibility and digestion-inhibiting substances. Plants from which the samples are drawn are all important in the diet of western gorillas, large generalist herbivores in coastal Cameroon. Many of the plants are common in the early succession following disturbance to the forest. Analysis of food chemistry in relation to food preference indicates that lignin, digestibility and crude protein are the most significant factors in food selection for western gorillas at this site. Food chemistry of western gorillas is compared to food chemistry of mountain gorillas in the montane forest of East Africa. Foliage consumed by western gorillas contains more condensed tannin than does foliage consumed by mountain gorillas. The greater content of condensed tannin in the leaves consumed by western gorillas is related to the greater representation of woody plants in the western diet.     

First archaeological evidence of banana cultivation in central Africa during the third millennium before present

Phytoliths recovered from refuse pits excavated in central Cameroon and dated to ca 2500 B.P. have been positively identified for the first time in Africa as derived from Musa the cultivated banana, after a comparative study of Musa and Ensete phytoliths. This discovery provides archaeologists with unequivocal proof of early agriculture in central Africa. Furthermore, the presence of banana in Cameroon much earlier than previously assumed could explain how agriculture spread through the rain forest. Lastly, as Musa is of Asian origin, this study provides the first concrete evidence of contacts across the Indian Ocean a millennium earlier than currently accepted. Received July 12, 1999 / Accepted May 4, 2000     

The<Emphasis Type="Italic"> Arabidopsis thaliana rlp</Emphasis> mutations revert the ectopic leaf blade formation conferred by activation tagging of the<Emphasis Type="Italic"> LEP</Emphasis> gene

Activation tagging of the gene LEAFY PETIOLE ( LEP) with a T-DNA construct induces ectopic leaf blade formation in Arabidopsis, which results in a leafy petiole phenotype. In addition, the number of rosette leaves produced prior to the onset of bolting is reduced, and the rate of leaf initiation is retarded by the activation tagged LEP gene. The ectopic leaf blade results from an invasion of the petiole region by the wild-type leaf blade. In order to isolate mutants that are specifically disturbed in the outgrowth of the leaf blade, second site mutagenesis was performed using ethane methanesulphonate (EMS) on a transgenic line that harbours the activation-tagged LEP gene and exhibits the leafy petiole phenotype. A collection of revertant for leafy petiole ( rlp) lines was isolated that form petiolated rosette leaves in the presence of the activated LEP gene, and could be classified into three groups. The class III rlp lines also display altered leaf development in a wild-type (non-transgenic) background, and are probably mutated in genes that affect shoot or leaf development. The rlp lines of classes I and II, which represent the majority of revertants, do not affect leaf blade outgrowth in a wild-type (non-transgenic) background. This indicates that LEP regulates a subset of the genes involved in the process of leaf blade outgrowth, and that genetic and/or functional redundancy in this process compensates for the loss of RLP function during the formation of the wild-type leaf blade. More detailed genetic and morphological analyses were performed on a selection of the rlp lines. Of these, the dominant rlp lines display complete reversion of (1) the leafy petiole phenotype, (2) the reduction in the number of rosette leaves and (3) the slower leaf initiation rate caused by the activation-tagged LEP gene. Therefore, these lines are potentially mutated in genes for interacting partners of LEP or in downstream regulatory genes. In contrast, the recessive rlp lines exhibit a specific reversion of the leafy petiole phenotype. Thus, these lines are most probably mutated in genes specific for the outgrowth of the leaf blade. Further functional analysis of the rlp mutations will contribute to the dissection of the complex pathways underlying leaf blade outgrowth.Communicated by G. Jürgens     

A new species of Grindelia (Asteraceae, Astereae) from the Meseta del Somuncura (Patagonia), Argentina

Grindelia coronensis, a new species from the Meseta del Somuncura, Prov. Río Negro, Argentina, is described and illustrated. It is similar toG. chiloensis (Cornel.) Cabrera but it is readily distinguished by its leaves which are conspicuosly differentiated into a obovate blade and a long petiole.     

Tropaeolum sparrei sp. nov. (Tropaeolaceae) from western Ecuador

A new species, Tropaeolum sparrei Ståhl (Tropaeolaceae), is described from submontane cloud forest habitat in western Ecuador. It differs from T. papillosum Hughes (the species it resembles most) by having thinner, tomentose stems, smaller, glabrous or subglabrous leaves with the petiole inserted relatively closer to the lower leaf margin, and flowers with uniformly coloured and straight calyx spurs. In leaf shape it is also similar to T. repandum Heilborn, from which it differs in its larger flowers with entirely black petals and blue anthers.     

Diurnal oscillatory movements of growing leaves of tobacco

The analysis of diurnal oscillatory movements of tobacco leaves was used in the diagnosis of viral infection of plants. The oscillatory helices circumscribed by a growing leaf of a healthy plant were regular, but some deviations, particularly in the transition points, were recorded. In order to make clear the cause of these irregularities of trajectory, the course of elongation of leaf petiole and blade in relation to localization and shift of zones of elongation during ontogenesis was analysed. The present analysis is similar to that described by the author's earlier experiments with pea roots. Oscillatory curves circumscribed by petiole, projected on a horizontal plane, were compared with curves circumscribed by the blade tip. The analysis of the leaves of different ages enabled us to study this process in dependence on growth rate. It was confirmed that oscillations are a result of elongation; the extent of oscillations is quantitatively dependent on the growth rate. An analysis of the zones of growth showed that in petiole the active meristems are localized near to its base while in the leaf lamina they move gradually during the ontogenesis from the apical to the basal part of the leaf blade. Active meristems of young rapidly growing leaves are localized approximately in the middle of the blade while those of old leaves were found in close proximity to the base of the lamina. The growth rate of petiole can be expressed in hundreds of mm per hour (4.8×10^?2 mm h^?1); half of this value was recorded for its apical part. The growth rate of leaf blade was found approximately ten times higher (3.2×10^?1 mm h^?1). The oscillatory movements of growing leaf consists of two integrate components: of oscillations originating in the base of the petiole and of oscillations of leaf blade the centrum of which is localized in the basal third of the blade. The arrangement of the experiments did not enable us to determine to what extent the phototropic response of leaf blade participates in leaf movements. The movements of leaves of an intact plant are evidently affected by rhythmic stem oscillations. Stem is an integral part of a system which participates in the transfer of information in plants.     

Decrement and amplification of slow wave potentials during their propagation in<Emphasis Type="Italic"> Helianthus annuus</Emphasis> L. shoots

Slow wave potentials (SWPs) are transitory depolarizations occurring in response to treatments that result in a pressure increase in the xylem conduits (P_x). Here SWPs are induced by excision of the root under water in 40- to 50-cm-tall light-grown sunflower plants in order to determine the effective signal range to a naturally sized pressure signal. The induced slow wave depolarization appears to move up the stem while it is progressively decremented (i.e. the amplitude decreases with increasing distance from the point of excision) with a rate that appears to rise acropetally from 2.5 to 5.5% cm^–1. The decline of the SWP signal, in both amplitude and range, could be experimentally increased (i) when root excision was carried out in air and (ii) when the transpiration of the sunflower shoot was minimized by a preceding removal or coating of the leaves. A further decline of the SW signal was expected to occur when leaves were included in the measured path. However, when the most distant apical electrode was attached to an upper leaf, it showed a considerably larger depolarization than a neighboring stem position. This apparent amplification of the SWP signal is not confined to the leaf blade but includes the petiole as well. The amplification disappeared (i) when the illumination level was lowered to room light, (ii) when the blade was excised either completely or along the remaining midvein and (iii) when the intact leaf blade was submersed in water. These treatments reduce the SWP at the petiole to a small fraction of the signal in the opposite control leaf and specify bright illumination and blade-mediated transpiration as prerequisites of a signal increase that is confined to young, expanding leaves.     

Epistemma neuerburgii (Apocynaceae, Periplocoideae): A new epiphytic species from Nyungwe National Park, Rwanda, Africa

A new species, Epistemma neuerburgii is described. This species was discovered in the Nyungwe National Park, Rwanda, Tropical Africa during a field investigation of epiphytes in montane rainforest. It was, however, also found in Uganda, in similar environment. E. neuerburgii is the fourth species described for Epistemma, but the other three species are found about 2000 km to the west in Cameroon, Gabon, Ghana, Ivory Coast and Nigeria. E. neuerburgii is an epiphytic climber distinguished by fairly large lanceolate leaves and conspicuous reddish-purple flowers with corolline white, densely hairy corona lobes.     

Developmental events leading to peltate leaf structure in <Emphasis Type="Italic">Tropaeolum majus</Emphasis> (Tropaeolaceae) are associated with expression domain changes of a YABBY gene

Peltate leaf architecture has evolved from conventional bifacial leaves many times in flowering plant evolution. Characteristics of peltate leaves, such as the differentiation of a cross zone and of a radially symmetric, margin-less petiole, have also been observed in mutants of genes responsible for adaxial-abaxial polarity establishment. This suggests that altered regulation of such genes provided a mechanism for the evolution of peltate leaf structure. Here, we show that evolution of leaf peltation in Tropaeolum majus, a species distantly related to Arabidopsis thaliana, was associated with altered expression of Tropaeolum majus FILAMENTOUS FLOWER (TmFIL), a gene conferring abaxial identity. In situ hybridization indicates that adaxial and abaxial domains are established in early leaf primordia as in species with bifacial leaves. Upon initiation of the cross zone by fusion of the blade margins, localized expansion of TmFIL to the upper leaf side could be seen, indicating a local loss of adaxial leaf identity. The observed changes in expression are consistent with a role of TmFIL in radialization of the petiole and circularization of the leaf blade margin by the cross zone. In addition, expression was observed in segment primordia and during expansion of the bifacial blade, suggesting additional roles for TmFIL in leaf development.     

Pinnately ramified ensiform leaves in the genus Marathrum, (Podostemaceae-Podostemoideae)

The paper deals with the complex leaves of three species of the aquatic genus Marathrum (M. minutiflorum, M. rubrum and M. schiedeanum). It is shown that they represent pinnately ramified ensiform leaves. The dissection of the leaves contributes to surface enlargement and thus to improvement of their hydrophylls function. The ensiform structure is confirmed by the transverse position of the sheathing lower leaf zone and the subsequent intercalary elongational growth proceeding in the median plane towards the abaxial side of the leaf (upper leaf zone). The petiole continues into the rachis-like central axis of the blade from which pinnate-like segments diverge at the adaxial and abaxial edge of the ensiform blade. The segments give rise to tufts of clavate enations that end in long filaments. The filigree pinnately segmented ensiform leaves of Marathrum are interpreted as a further development of the fan-shaped and irregularly lobate ensiform leaves occurring in Mourera and Apinagia. Pinnately ramified ensiform leaves obviously evolved in convergence to the common type of pinnate leaves found in angiosperms.     

Adjustment of foliage structure and function to a canopy light gradient in two co-existing deciduous trees. Variability in leaf inclination angles in relation to petiole morphology

 Foliar inclination angles, petiole morphology and dry matter partitioning between assimilative and support biomass were studied in shade-intolerant Populus tremula L. and shade-tolerant Tilia cordata Mill. along a natural light gradient across the canopy. The leaves of sub-canopy species T. cordata were on average exposed to lower irradiances, and they were also more horizontal with greater blade inclination angles (ϕ_B, defined as the angle between the leaf fall-line and the horizon; ϕ_B was positive for the leaves inclined upwards, and negative for the leaves inclined downwards) than those in P. tremula. Seasonal average daily integrated quantum flux density (Q _int, mol m^–2 day^–1) and ϕ_B were not related in T. cordata, and only a weak negative effect of Q _int on ϕ_B was detected in P. tremula. Nevertheless, when both species were pooled, there was a strong negative relationship between Q _int and ϕ_B, implying that the leaves became progressively vertical with increasing height in the canopy. Interspecific differences in foliage inclination were mainly related to petiole morphology, in particular to petiole length, rather than to contrasting biomass investment patterns between assimilative and support tissues within the leaf. It was suggested that more horizontal leaves, resulting from the species-specific structure of petioles, partly explain the superior performance of shade-tolerant T. cordata in the understory and the sub-canopy. Received: 13 November 1997 / Accepted: 6 March 1998     

The Branchiopoda (Crustacea: Anomopoda, Ctenopoda and Cyclestherida) of the rain forests of Cameroon, West Africa: low abundances, few endemics and a boreal–tropical disjunction

Aim We provide the first in‐depth study of the Branchiopoda of the rain forests of Cameroon and also of the African continent. Location Surface water environments, Cameroon. Methods Qualitative plankton samples were collected in all types of surface water environments present, ranging from big lakes to water collected in rock crevices or fallen fruit cavities. A tow or hand‐held plankton net of mesh size 100 μm was used, and water volumes filtered were at least several m³ in large water bodies, or half to whole water volume in small water bodies. Results We recorded 61 species (53 first records for the country), based on 700+ samples collected between September 1998 and March 2002. Anomopoda (92%) was the dominant order, followed by Ctenopoda (6.5%) and Cyclestherida (1.5%). Chydoridae (67%) was the most speciose family followed by Macrothricidae (6.5%) and Daphniidae (5%). Alona (11%) was the dominant genus followed by Chydorus (10%) and Pleuroxus (8%). Several species of Chydorinae, especially of the genus Pleuroxus, are shared with continental Eurasia–North America, but are absent from the Mediterranean and desert–steppe–savanna zones of Africa (boreal–tropical disjunction). Daphnia was absent, as in most tropical lowlands. No single species was really abundant, and a majority were rare to very rare, and of restricted occurrence within the rain forest patches. Comparing Africa, South America and Southeast Asia, we found a current total of 196 species for the combined rain forest areas, out of a world total of 500+ species. Systematic trends in richness at three taxonomic levels were the same for all continents: Anomopoda–Ctenopoda–Cyclestherida at ordinal level, Chydoridae–Daphniidae–Macrothricidae–Sididae at family level and Alona–Chydorus–Macrothrix–Diaphanosoma at genus level. Southeast Asia was richest (111 species, 14 endemics) with South America a close second (110 species, 27 endemics). Africa was the most species‐poor (95 species, of which only 5 are endemics). Main conclusions We hypothesize that the post‐Miocene cooling and aridization of the world climate hit the freshwater biota of Africa particularly hard, with more extinction here than elsewhere, and little recolonization. Most extinction occurred in the savanna‐desert belt, and eight disjunct boreal species (four Pleuroxus, Picripleuroxus laevis, Kurzia latissima, Alonella exigua, and Monospilus dispar) survive morphologically unchanged since pre‐Pleistocene times in the Cameroon rain forest. Slow evolution thus appears typical of these cyclic parthenogenetic branchiopods in which sexual recombination occurs only at intervals. Illustrative of the same slow evolution is the fact that the two endemic cladocerans of Cameroon (Nicsmirnovius camerounensis and Bryospilus africanus) belong to tropicopolitan genera of Gondwanan age.     

Leaf development and phloem transport in Cucurbita pepo: Transition from import to export

Summary The capacity of a growing leaf blade of Cucurbita pepo L. to import ¹⁴C-labelled photoassimilate is lost in a basipetal direction. Import into the lamina tip stops when the blade is 10% expanded. Development of the leaf progresses linearly with time and the lamina base stops importing when the blade is 45% expanded. Export capacity also develops basipetally and follows immediately the loss of import capacity, at least in the lamina base. The small amount of material initially exported from the leaf tip is redistributed to the still-importing leaf base, delaying export from the lamina until the blade is 35% expanded. Loss of import capacity by the petiole is both basipetal and dorsoventral. The proximal, adaxial portion of the petiole is the last region to cease importing ¹⁴C. Leaves of Beta vulgaris L. and Nicotiana tabacum L. also lose import capacity in a basipetal direction.     

The ancient tropical rainforest tree Symphonia globulifera L. f. (Clusiaceae) was not restricted to postulated Pleistocene refugia in Atlantic Equatorial Africa

Understanding the history of forests and their species'' demographic responses to past disturbances is important for predicting impacts of future environmental changes. Tropical rainforests of the Guineo-Congolian region in Central Africa are believed to have survived the Pleistocene glacial periods in a few major refugia, essentially centred on mountainous regions close to the Atlantic Ocean. We tested this hypothesis by investigating the phylogeographic structure of a widespread, ancient rainforest tree species, Symphonia globulifera L. f. (Clusiaceae), using plastid DNA sequences (chloroplast DNA [cpDNA], psbA-trnH intergenic spacer) and nuclear microsatellites (simple sequence repeats, SSRs). SSRs identified four gene pools located in Benin, West Cameroon, South Cameroon and Gabon, and São Tomé. This structure was also apparent at cpDNA. Approximate Bayesian Computation detected recent bottlenecks approximately dated to the last glacial maximum in Benin, West Cameroon and São Tomé, and an older bottleneck in South Cameroon and Gabon, suggesting a genetic effect of Pleistocene cycles of forest contraction. CpDNA haplotype distribution indicated wide-ranging long-term persistence of S. globulifera both inside and outside of postulated forest refugia. Pollen flow was four times greater than that of seed in South Cameroon and Gabon, which probably enabled rapid population recovery after bottlenecks. Furthermore, our study suggested ecotypic differentiation—coastal or swamp vs terra firme—in S. globulifera. Comparison with other tree phylogeographic studies in Central Africa highlighted the relevance of species-specific responses to environmental change in forest trees.     

Magnolia tiepii sp. nov. from Vietnam

A new species of Magnolia sect. Gwillimia DC., Magnoliaceae from Vietnam is described and illustrated. Magnolia tiepii is recognized from southern Vietnam, where it occurs in Khanh Vinh slope, Khanh Vinh District, Khanh Hoa Province. It is distinguished from the closely related M. henryi by having narrowly cuneate leaf blade, short petiole, stipular scar at the base of the leaf blade, short peduncle and ellipsoid fruit.     

Isolation of endophytic fungi from leaves of Pasania edulis and their within-leaf distributions

 Endophytic fungi were isolated from leaves of Pasania edulis, one of the most important trees of the warm temperate forests in southern Kyushu, by the surface sterilization method using H₂O₂ as a sterilizing agent. From a tree in the Experimental Nursery of Kagoshima University, located at the city of Kagoshima, Phyllosticta sp. and Colletotrichum spp. were frequently isolated. From a stand in a laurel forest in Mt. Takakuma, an ascomycetous fungus (Ascomycete sp. 1) and Phomopsis sp. were frequently isolated. Phyllosticta sp. was isolated more frequently from petiole segments and leaf segments with midrib and Phomopsis sp. from petiole segments and leaf-base segments with midrib than other segments. Colletotrichum spp. were isolated less frequently from petioles and Ascomycete sp. 1 from petiole segments and leaf-base segments with midrib than other segments. As possible causes of such biases in within-leaf distributions of the endophytes, differences in infection modes and negative interactions of major endophytes within leaves are suggested. Received: December 13, 2001 / Accepted: June 7, 2002 Acknowledgments The authors thank the staff members of the Experimental Forests of Kagoshima University for enabling the present study. Correspondence to:K. Hata     

Direct organogenesis in Indian spinach

An efficient and reproducible protocol for plant regeneration through in vitro culture of Indian spinach (Beta palonga) is reported. Shoot buds were obtained both from blade petiole transition zones and midribs of fully expanded leaves. Murashige and Skoog's basal medium supplemented with naphthaleneacetic acid and benzyladenine (each at 1 mg l^–1) resulted in high frequency shoot organogenesis. Histological studies showed that the origin of shoot primordia was sub epidermal.