Dicotyledonous Angiosperms Research Articles

Sediment Facies, Depositional Environments, and Distribution of Phytoclasts in the Recent Mahakam River Delta, Kalimantan, Indonesia

The Mahakam River delta is a tide- and wave-dominated delta located on the edge of the Kutei basin, eastern Kalimantan, Borneo. It is a coastal deltaic sequence, Neogene to Holocene in age, from which all recoverable hydrocarbons (crude oil and natural gas) are considered to be derived from kerogen III predecessors. However, a complete understanding of the types of sediments sourcing the hydrocarbons has not yet been achieved. A vibracoring program sampled the principal fine-grained depositional environments in two transects; one within the fluvially-dominated regime, one within the tidally-dominated regime. Ten sedimentary facies are distinguished and phytoclasts have been recovered from all environments of deposition. Canopy parts from the mixed tropical forest community are preserved throughout the delta, whereas dicotyledonous angiosperm mangroves are restricted to the subtidal zone and delta front. Nypa parts are preserved in most depositional environments. In sites where there appears to be an absence of macrodetritus, dispersed cuticle is recoverable. Identifiable plant parts include wood and fibrous tissues, Nypa petioles and leaf laminae, dicotyledonous angiosperm leaves and isolated cuticles, fruits and seeds, roots and rootlets, and moss. Dammar is found either as dispersed resin ducts or amorphous clasts. Additional biotic components found in bedded plant littersmore » include insects, gastropods, bivalves, sand dollars, ostracods, and crabs. Fluvial channels and depositional sites associated with these systems in the delta front can be differentiated from Nypa swamps and mixed tropical hardwood-palm swamps based on their phytological components and accessory biotic elements. 39 refs., 10 figs., 3 tabs.« less

The fracture toughness of the leaf of the dicotyledon Calophyllum inophyllum L. (Guttiferae)

The fracture toughness (specific work of fracture) of the leaf of the dicotyledonous angiosperm, Calophyllum inophyllum L. (Guttiferae), which has a lamina with a reticulate venation comprising secondary and tertiary veins only, was investigated by cutting, notched tensile and punch-and-die tests. Toughness was found to depend on the presence of veins in the fracture path, with both tensile and cutting tests in agreement that fracture at right angles to secondary veins was 2.5-3.0 times as tough as fracture parallel to them. Values from tensile tests were smaller than those from cutting tests. The cutting method had the advantage of specifying the direction of fracture and of severing structures serially, allowing easy recognition of tough structures from force-displacement records. This showed that the fracture toughness of the lamina could be modelled by a ‘rule of mixtures’ whereby the veins (vascular bundles supported by sclerenchyma strands above and below), with a combined toughness of about 6000 J m -2 , are contrasted to other tissues - the mesophyll and the epidermis and its cuticle — which together probably have an average toughness of only 220-300 J m -2 . Bounds on the toughness of mature leaves are probably set close to these limits. However, we could not test all these tissues separately to confirm this. The model predicted the fracture toughness expected in a cylindrical punch-and-die test, which is the commonly used test in ecological studies. However, observed values from this test were twice those expected, which is mostly attributable to yielding of a large volume of mesophyll but also in part due to the debonding of secondary veins from the rest of the lamina. The results suggest that relevant classifications of leaves (sclerophyll, pachyphyll, etc.) should pay close attention to the venation of the leaf and the structure of these veins. It is proposed that the thickening of the walls of smaller veins to form a venous network is a defence against invertebrate herbivores.

Reservation status and priorities for Tasmanian plants I. Angiospermae (Dicotyledonae)

Almost one-fifth of Tasmanian native dicotyledonous angiosperms are not known from any national park or equivalent reserve. Extinct, endangered, vulnerable and unreserved species are most common among annuals and least common among woody plants. The unreserved species have their distributions concentrated between Launceston and Hobart in the dry, naturally grassy Midlands. A minimum reservation strategy is suggested for those species for which this option still exists.

Sequence of the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase from a gymnosperm, Douglas fir

The chloroplast rbcL gene encodes the large subunit ofribulose 1,5-bisphosphate carboxylase [ 3 ], the enzyme that catalyzes CO 2 fixation during photosynthesis [6]. rbcL nucleotide sequences data have been used extensively, and proven to be quite powerful, in studies of plant phylogeny and molecular evolution [9, 10]. Complete sequences have been determined from several monocotyledonous and dicotyledonous angiosperms, algae, photosynthetic bacteria, and a bryophyte [7, 9, 10]. We report here an rbcL gene sequence from a Pinaceous gymnosperm, Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). rbcL was sequenced by the dideoxynucleotide chain termination method using recombinant plasmid DNA as the template [2]. In addition to the 1425 base pair (bp) coding region, we sequenced 251 bp upstream and 179bp downstream of the open reading frame (Fig. 1). The coding region has an inferred amino acid sequence that is 93.0% similar to tobacco [4], 90.3% to maize [5, 8], and 92 .4~ to liverwort [7]; its DNA sequence is 85.8%, 83.8%, and 82.6 % similar, respectively. There is a deletion of one codon and an insertion of one codon in the Douglas fir sequence relative to maize, and a deletion of two codons relative to tobacco. The 5' flanking region contains prokaryoticlike consensus promoter sequences and ribosome binding site. Possible 35 (TTGCAT) and 10 (TACAAT) regions are located at positions 80 to 85 and 103 to 108, respectively (underlined in Fig. 1) and are separated by a 17 bp AT-rich region. The Douglas fir rbcL 35 sequence differs in two nucleotide positions from angiosperm sequences (TTGCAT instead of TTGCGC) [4, 10]. The putative ribosome binding site [1] is also underlined, and located at nucleotides 242 to 246. Two likely stem-loop transcription termination structures [ 10] are present in the 3' flanking region (horizontal arrows in Fig. 1).

Lignin in wheat internodes. Part 2: Alkaline nitrobenzene oxidation by wheat straw lignin and its fractions

AbstractFinely ground 80 % ethanol extracted residues of maturing wheat internode sections of the first internode were successively extracted with 96 % dioxane to give milled lignin (ML1) and water soluble ( MC1) fractions. The residue was treated with a polysaccharide hydrolase mixture to give soluble fractions (EC1) and a residue (ER1). The ML1 fractions were minor components at all stages of maturation. The yield of the MC1 fractions decreased during maturation whereas the yield of ER1 fractions increased. The acetyl bromide lignin content increased )om 11.5 to 16.2% between the youngest and oldestinternode sections.The ratio of syringyl to guaiacyl nuclei (S/V) in internode sections and fractions showed a trend towards a slight increase with maturity. The p ‐hydroxyphenyl to guaiacyl ratios (H/V) were low except for the youngest internode sections, and are comparable to those for gymnosperms and dicotyledonous angiosperms. FTIR spectroscopy of Björkman lignins from mature wheat internodes were characterised on the basis of the ratio of peak intensities in the ranges 1420–1510 cm−1, 1240–1260 cm−1 and 1040–1130 cm−1, and were found to have values intermediate between pine and eucalypt Björkman lignins.The MC1, jaction was rich in ferulic acid and p‐coumaric acid as determined by alkaline nitrobenzene oxidation and UV spectroscopy. This accounts for the high acetyl bromide lignin content of the internodes. The yield of cinnamic acids increased as the internodes matured. The phloroglucinol test, indicative of cinnamaldehyde derivatives, was negative in the youngest internodes but became positive with increasing maturity. The Mäule colour reaction (red purple colour) was not given by any wheat internode sample (S/V < 2). In contrast, samples from dicotyledonous angiosperms (S/V > 2) all gave positive tests.

Resistance of hardwood vessels to degradation by white rot Basidiomycetes

White stringy rot, an unusual type of selective fungal decay, can be found in wood of some dicotyledonous angiosperms. Stages of advanced decay consist of a mass of vessel elements with only remnants of other cells adhering to the vessel walls. Degradation by various white rot Basidiomycetes causes loss of fibers, fiber tracheids, and parenchyma cells but not vessels. In wood of Acacia koa var. koa with a white pocket rot caused by Phellinus kawakamii, fibers and parenchyma cells were preferentially delignified. After extensive lignin removal the cellulose remaining in the secondary wall was degraded. Large vessel elements remained relatively intact after other cells were completely degraded. The resistance of vessels to degradation appears to be due to their high ligninxarbohydrate ratio, lignin monomer composition, and cell wall morphology.

A role for haemoglobin in all plant roots?

Abstract. We have found haemoglobin in plant roots whereas previously it has been recorded only in nitrogen fixing nodules of plants. Haemoglobin occurs not only in the roots of those plants that are capable of nodulation but also in the roots of species that are not known to nodulate. We suggest that a haemoglobin gene may be a component of the genome of all plants. The gene structure and sequence in two unrelated families of plants suggests that the plant haemoglobins have had a single origin and that this origin relates to the haemoglobin gene of the animal kingdom. At present we cannot completely rule out the possibility of a horizontal transfer of the gene from the animal kingdom to a progenitor of the dicotyledonous angiosperms but we favour a single origin of the gene from a progenitor organism to both the plant and animal kingdoms. We speculate about the possible functions of haemoglobin in plant roots and put the case that it is unlikely to have a function in facilitating oxygen diffusion. We suggest that haemoglobin may act as a signal molecule indicating oxygen deficit and the consequent need to shift plant metabolism from an oxidative to a fermentative pathway of energy generation.

Studies of peat as the input to coalification, II. Sampling sites and preliminary fractionation

Five investigational sites in the Florida Everglades and Okefenokee Swamp have been selected in which the present vegetational cover includes a gymnosperm and various monocotyledonous and dicotyledonous angiosperms, and cores have been obtained that represent complete profiles from surface to underlying inorganic sediment. Since previous methods of fractionating peat were regarded as unsatisfactory for various reasons, a purely mechanical technique has been used in which organized plant tissue is separated from fine-grained humic matter by slurrying the peat samples in an excess of water and passing the slurry through standard 20 and 80 mesh sieves. Microscopic examination confirms that the coarse fraction consists of fragments of tissue and organs, though not all such fragments can be assigned to a specific source plant. Fragments of roots or rhizomes tend to dominate. Peats from sites in the proximity of saline waters have high sulfur contents (3–5%), most of the sulfur being combined with the organic matter. Nitrogen contents are high, most probably due to the presence of abundant amino acids condensed with the insoluble organic matter.

A new citrus‐feeding psyllid from the Comoro Islands, with a review of the Diaphorina amoena species group (Homoptera)

ABSTRACT. Analysis of host plant data for the seventy‐one species of Diaphorina shows the genus to be unusually polyphagous, the species developing on eighteen families of dicotyledonous angiosperms. Apart from the common Asian citrus pest, Diaphorina citri, a second citrus‐feeding species is described and discussed. This species belongs to the amoena species‐group which is defined and a key to nine of the ten included species is given. Seven new species are described: flavipennis sp.n. and nigripennis sp.n. from East Africa on Strychnos usambarensis; huila sp.n. from Angola on Ptaeroxylon obliquum; turned sp.n., from South Africa (host unknown); orantimina sp.n. from Madagascar (host unknown); auberti sp.n. from Comoro Islands on citrus trees; and bispinulata sp.n. from Madagascar (host unknown).

Zeatin biosynthesis from N 6 -(Δ 2 -isopentenyl)adenine in Actinidia and other woody plants

Tissue cultures of Actinidia kolomikta can be maintained as callus through repeated passages on a nutrient medium devoid of cytokinin but containing inorganic nutrients, sucrose, and other basal organics plus auxin. Under these conditions, actively growing callus contained 2 and 0.5 nmol of the cytokinins zeatin [io(6)Ade; 6-(4-hydroxy-3-methylbut-2-enylamino)purine] and N(6)-(Delta(2)-isopentenyl)adenine (i(6)Ade), respectively, per gram (fresh weight). When tissues were transferred from cytokininless medium to 30 muM i(6)Ade, endogenous io(6)Ade increased linearly to 160 nmol/g (fresh weight) during 8 hr, and i(6)Ade increased to 5 nmol/g (fresh weight) in 2 hr and then declined. The apparent K(m) for i(6)Ade in A. kolomikta and Actinidia chinensis x Actinidia arguta callus and in tissue slices of A. arguta stems was 12 muM. In addition, the reaction(s) converting i(6)Ade to io(6)Ade was O(2)-requiring and specific for i(6)Ade versus N(6)-(Delta(2)-isopentenyl)adenosine (i(6)A). When A. kolomikta callus was fed 30 muM i(6)A, io(6)Ade increased and reached a concentration corresponding to 6 nmol/g (fresh weight) in 8 hr. Ribosylzeatin (io(6)A) did not increase. Under N(2) during i(6)A feeds, i(6)A accumulated rather than being metabolized to i(6)Ade, suggesting that i(6)A normally may be metabolized via i(6)AMP and i(6)Ade to io(6)Ade. A survey of 30 species of woody plants in 20 families of dicotyledonous angiosperms indicated that the ability to accumulate io(6)Ade (>/=10 nmol/g) in 24-hr feeds with 30 muM i(6)Ade was restricted to certain systematic groups-e.g., order Ericales, families Oleaceae and Rubiaceae. This suggests that plants may differ in their pathways for io(6)Ade biosynthesis and that cytokinin biochemistry has potential as a taxonomic character above the species and genus levels.

Polyploidy in plant taxa: summary.

The preceding seven papers deal with the distribution and evolutionary significance of Polyploidy in each of the major plant taxa. Polyploidy, the multiplication of entire chromosomal complements, is the most widespread and distinctive cytogenetic process affecting higher plant evolution. Approximately 36% of the species of flowering plants have gametic chromosome numbers which are multiples of the basic diploid number found within their respective genera, but between 70 and 80 percent may, in fact, have Polyploidy in their evolutionary history. The percent of intrageneric Polyploidy in ferns is even higher and the occurrence of intergeneric Polyploidy is equivalent to that in angiosperms. Studies to date have been largely confined to the aforementioned groups, especially the dicotyledonous angiosperms. However, the preceding papers suggest that Polyploidy may be an important aspect of evolution among at least certain groups of the thallophytes. The only group in which Polyploidy is con-spicuously rare is the gyminosperms.KeywordsChromosome NumberBase NumberPlant TaxonBase Chromosome NumberHigh Chromosome NumberThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Chemistry and Structure of Natural Rubbers

Abstract Natural rubbers are synthesized in thousands of species covering most plant families; moreover, rubber has been obtained commercially from over a dozen of them. A later report has suggested that polyisoprene formation is limited to dicotyledonous angiosperms. In recent years there has been renewed interest in developing alternative sources of natural rubber, different from Hevea brasiliensis. In particular there has been considerable development of guayule as a source of natural rubber. As a result there is a considerable body of recent results, using new techniques and extending older work concluded in the 1950's, which give new insight into the production of rubber in plants. This paper will mainly deal with guayule because it can ideally serve as a background for understanding the production of rubbers in other plants, including hevea. First, it is necessary to describe the physical nature of the rubber from guayule and where in the plant it is formed. Figure 1 shows a cross-section of a stem of guayule. The individual cells (parenchyma cells) are the site of rubber manufacture. The rubber can finally be seen as the small latex droplets inside a single cell (Figure 2). Thus the study of the natural rubber in guayule involves the isolation of the latex particles from the cell. It is extremely easy to separate an industrial rubber from other parts of the plant, including resin, by either laboratory or pilot plant methods. However, it is more difficult to get fresh latex in which no additional particle coagulation has occurred. The description of the average latex particle size and the distribution of sizes has been made and is needed to discuss the biosynthesis of rubber. It will not be discussed further. The question addressed in this paper is the chemical structure of the rubber in the plants—the micro-structure of the rubber, the molecular weight distribution, and the branching or gel content. Guayule natural rubber has the remarkable feature of containing no gel when taken directly from a fresh plant and carefully handled in the laboratory. Even the material from the pilot plant extraction process contains only 1–3 per cent gel. This paper describes extensively the chemical structure of natural rubber extracted from fresh guayule plants. Less extensive measurements on chicle, gutta-percha, and castilla elastica are also reported. Finally, all of the data are analyzed to determine if a model of rubber production can be formulated to encompass all of the above plants. Earlier, a model was proposed for guayule only. In this model the polyisoprene chain is polymerized on the polymerase enzyme site by recurring attachment and intermittent polymerization until the rubber droplet (containing a single polymer chain) can no longer be stabilized or further polymerized by the enzyme.

Diallyl di-, tri- and tetrasulphide from Adenocalymma alliaceae

The essential oil from flowers and leaves of Adenocalymma alliaceae (Bignoniaceae) consists almost entirely of diallyl di-, tri-and tetra-sulphide, a mixture formerly encountered within the Allium genus but never before convincingly recognized within the class of dicotyledonous angiosperms.

An evolutionary comparison of plant histones

Histones were extracted from chromatin of the following: a moss ( Polytrichum juniperinum); the primitive vascular plants Psilotum nudum and Equisetum arvense; a fern ( Polypodium vulgare); the gymnosperms fir ( Abies concolor), yew ( Taxus canadensis) and Gingko biloba; the dicotyledonous angiosperms tobacco ( Nicotiana tabacum) and maple ( Acer saccharinum); and the monocotyledonous angiosperms corn ( Zea mays) and lily ( Lilium longiflorum). The histones were subjected to polyacrylamide gel electrophoresis and compared to standard histones of pea ( Pisum sativum) and cow ( Bos taurus). All species have histones of the exact electrophoretic mobility of histones F2a1 and F3 of cow and pea. All species have histones of low electrophoretic mobility assumed to be F1 histones. None of the plant histones displayed electrophoretic mobility between F3 and F2a1 while animal histone fractions F2b and F2a2 do migrate to this position. No animal histone fraction was found to migrate between F3 and F1 while a major plant fraction, designated “F2b-like” was found to migrate to this position in all plant species studied except for the moss and Psilotum. A band of similar mobility was strikingly absent from the histones of these two species.

Studies on the Initial Biochemical Reactions in the Germination of Pollen Grains

Tritiated water (3HHO) has been used as the medium for the germination of pollen grains of Pinus radiata D.Don (a gymnosperm), Ulex europaeus L., Salix caprea L. (dicotyledonous angiosperms), and Phormium tenax Forst. (a monocotyledonous angiosperm). 3H-labelled compounds formed during the initial germination (egersis) period have been separated and identified to give information on the metabolism taking place. Since the earliest labelled compounds were y-aminobutyric acid, alanine, aspartic acid, and glutamic acid, it is concluded that these amino acids play an important part in the biochemical reactions during the early stages of germination. Citric acid, malic acid, and glutamine do not become labelled until later while carbohydrates, phosphate esters, and lipids do not appear to incorporate tritium within the first hour of germination. The gross labelling pattern and the nature of the individually labelled meta bolites, their intensity and sequence of labelling are similar for all the species investigated except gorse, which showed a decrease in the intensity and the number of labelled metabolites with time. P. radiata pollen stored for 3 years under vacuum or carbon dioxide has a labelling pattern similar to freshly collected P. radiata pollen, except for a con siderable increase in the amount of an unknown metabolite (Compound X).

Microstructure of woody lignite from Darrang district area, Assam, India

The microstructural details of woody lignite from the Darrang district area in Assam have been studied; the lignite is derived from the secondary wood of a dicotyledonous angiosperm. Xylinite and resinite (brown and yellow resins) are the main petrological constituents. The common occurrence of resins accounts for the high volatile content of the lignite. Films of clayey matter occupy the fracture and joint planes and account for the variable proportion of ash content. Sulphur is low, which indicates formation of the lignite in conditions other than marine.

Host Plants and the Locations of the Baggy and Compact Cocoons of Hyalophora cecropia (Lepidoptera: Saturniidae)

In the autumn and winter of 1965–66, 482 cocoons of Hyalophora cecropia (L.) were collected in urban environments in and near Champaign and Urbana, Illinois. In this area at least 26 plants of 12 families—all woody, dicotyledonous angiosperms—serve as hosts. Acer saccharinum L., Cornus stolonifera Michx., and C. alba L. are the most frequently utilized. Baggy cocoons are found almost exclusively at or near ground level on the stems of shrubs. Almost 60% of the cocoons found in such locations were baggy, while more than 99% of those found on the twigs and branches of trees were compact Whether or not a baggy cocoon is spun seems to depend upon the spacing of the available supports for the outer envelope of the cocoon.

CYTOLOGICAL CHARACTERISTICS ASSOCIATED WITH THE DIFFERENT GROWTH HABITS IN THE DICOTYLEDONS

IN REVIEWING the cytology of a number of different families of dicotyledonous angiosperms, the writer noted that although there were no characteristic differences between the chromosomes of the various larger systematic divisions of this subclass, there appeared to be, on the other hand, a definite set of characteristics associated with the different growth habits, particularly the woody plants as opposed to the herbs, and the annual or biennial as distinguished from the perennial species. In order to test this apparent phenomenon, he undertook a systematic review of the chromosomal characteristics of all dicotyledonous genera sufficiently recorded in the literature for this purpose. The results of this survey are recorded in the present paper. MATERIAL AND METHODS.-Three chromosomal characteristics were selected as the easiest to treat in the manner contemplated: (1) the basic chromosome number of a genus, (2) the percentage of polyploid species within a genus, and (3) the absolute size of the chromosomes within the genus. The data for the first two characteristics were obtained chiefly from the lists of Tischler (1931, 1936), while additional information on certain genera was obtained from more recent partial lists and from a few treatments of particular genera. In general, genera included in the classification by basic number and by absolute size are those of which at least five species are known, but unless the known species were fairly uniform in character, they were not admitted to the lists unless a larger number of species was recorded. For classification as to percentage of polyploidy, only those genera were selected of which 30 per cent or more of the species are known cvtologically, but an additional list was compiled including all the genera classified as to basic number. The basic number was considered that which was found, either in itself or in multiples of it, in fourfifths or more of the species of the genus. If a second number occurred in a considerable proportion of the species, the genus was given one-half value under each number, while if there were three, it was given onethird value under each of them. If there were more than 3 numbers in the genus, only the 3 most common ones were recorded. Numbers near to multiples of the lowest basic number were considered to be derived by polyploidy--e.g., if a genus contained the gametic numbers 8 and 17, the latter was considered as a hypertetraploid based on the former. Only those basic haploid numbers actually found in the genus were recorded; the evidence from secondary pairing was disregarded as being not firmly enough established and not recorded in a sufficient number of genera to be of use in a comprehensive survey such

Investigations on the Phylogeny of the Angiosperms. No. 2. Anatomical Evidences of Reduction in Certain of the Amentiferae

The earlier taxonomists by systematic studies, principally of external characters, have contributed much toward a truly natural classification of the angiosperms, but the problem is such an intricate one that in searching for a satisfactory solution evidence from all fields of botanical research must be considered and harmonized. In view of the assistance given by comparative anatomists in elucidating the phylogeny of gymnosperms and lower vascular plants, the recent hypothesis of Professor JEFFREY and his pupils, in regard to the development of aggregate, compound, and multiseriate rays in dicotyledonous angiosperms, merits careful consideration by taxonomists, since, if shown to rest on secure foundations, it is likely to produce radical changes in existing systems of classification.

Societies and Academeis

Societies and Academeis